M·O

Validation record

What each calculator stands on, what it refuses, which outside examples it reproduces, and who has checked it. Generated from the code on every build — it cannot say something the code does not.

This build

Engine build
2026.10.13 · validated 2026-10-13
Harness
2,381 engine assertions (141 external known-answer cases) + 877 page assertions + 574 adversarial assertions over 495 page runs
Calculators
99 · 53 transcribe a published table (22 standards) · 81 carry external known-answer cases (2 more state why not yet) · 0 independently reviewed
What a test count shows
That the engine still answers what its author expected. It does not show that a table was transcribed correctly, that every incompatible input is refused, or that a reviewer agreed. The external cases below are the part that was NOT written alongside the engine.
Sources of external cases
eval-2026-09-07 — Public-site evaluation, report dated 7 September 2026, targeted accuracy case register (31 cases). Response: AUDIT-EXTERNAL-2026-09-09.md (a report delivered to Tatum, not a public page; kept with the response)
niosh-94-110 — NIOSH Applications Manual for the Revised NIOSH Lifting Equation (Publication 94-110, January 1994), worked examples. Read from the scanned manual at https://ergo-plus.com/wp-content/uploads/NIOSH-Lifting-Equation-Application-Manual-94-110.pdf, fetched 27 Sep 2026: Example 1 p. 55, Example 3 p. 67, Example 5 p. 76, Example 6 p. 79. NIOSH's page for the publication: https://www.cdc.gov/niosh/publications/numbered/94-110.html
nws-heat — National Weather Service heat index chart, https://www.weather.gov/images/safety/heatindexchart-650.jpg (from https://www.weather.gov/ama/heatindex), fetched 27 Sep 2026: 96 °F at 60 % RH reads 116 °F
ecm-2011-chapter9 — EC&M, W. A. (Al) Werning, "How to Use Chapter 9 in Your Next Design", 24 May 2011, https://www.ecmweb.com/national-electrical-code/article/20885294/how-to-use-chapter-9-in-your-next-design, fetched 27 Sep 2026
nec-handbook-2017-t9 — NEC Handbook 2017, p. 1118: the Table 9 Note 2 worked example, as quoted in a Mike Holt forum post (23 Feb 2020), https://forums.mikeholt.com/threads/chapter-9-t9-note-2.2552202/, fetched 27 Sep 2026
ecm-2008-boxfill — EC&M, Mike Holt, "Box Fill Calculations", 31 Aug 2008 (NEC 2005; Table 314.16(B) volumes and counting rules unchanged in 2023), https://www.ecmweb.com/content/article/20886012/box-fill-calculations, fetched 28 Sep 2026
ecm-2022-pullbox — EC&M, Mike Holt, "Taking the Mystery Out of Sizing Pull Boxes and Junction Boxes", 2 Mar 2022 (NEC 2020; 314.28(A) unchanged in 2023), https://www.ecmweb.com/national-electrical-code/code-basics/article/21234199/taking-the-mystery-out-of-sizing-pull-boxes-and-junction-boxes, fetched 28 Sep 2026
temecula-fireflow — City of Temecula Fire Prevention Bureau, "Fire Flow Calculations With Examples" (NFPA 291 method), https://temeculaca.gov/DocumentCenter/View/164/Temecula-Fire-FlowCalculations-With-Examples-PDF, fetched 28 Sep 2026
wa-lni-noise — Washington State Department of Labor & Industries, "Noise Computation Examples" (90 dBA criterion, 5 dB exchange, as OSHA 1910.95 Appendix A), https://lni.wa.gov/safety-health/_docs/ht3-noise.pdf, fetched 28 Sep 2026
fcp-2010-formwork — For Construction Pros, Kim Basham, "Avoid too Much Pressure in Concrete", 1 Jul 2010 (ACI 347 wall formula), https://www.forconstructionpros.com/concrete/equipment-products/article/10289332/kb-engineering-llc-avoid-too-much-pressure-in-concrete, fetched 28 Sep 2026
foa-lossbudget — The Fiber Optic Association, "Calculating Fiber Optic Loss Budgets" (TIA-568 maximum values), https://www.thefoa.org/tech/lossbudg.htm, fetched 28 Sep 2026
ecm-2009-multifamily — EC&M, Mike Holt, "Multifamily Dwelling Unit Service and Feeder Calculations", 1 Dec 2009 (Table 220.84 factor for 12 units unchanged in 2023), https://www.ecmweb.com/national-electrical-code/code-basics/article/20891826/multifamily-dwelling-unit-service-and-feeder-calculations, fetched 28 Sep 2026
ecm-2014-workspace — EC&M Code Quiz, "Depth of Working Space", 30 May 2014 (NEC 2011 Table 110.26(A)(1); the 151-600 V condition 3 depth is unchanged in 2023), https://www.ecmweb.com/code-quiz-day/depth-working-space, fetched 28 Sep 2026
bline-tray-rules — Cooper B-Line, "Cable Tray Rules" (NEC 2002 Article 392; the 4/0-and-larger single-layer rule is 392.22(A)(1)(a) in 2023), https://fpg.phys.virginia.edu/fpgweb/nova/cable_trays/cable_tray_rules.pdf, fetched 28 Sep 2026
iaei-2019-pvmath — IAEI Magazine, John Wiles, "PV Systems Math — Sample Calculations", 5 Nov 2019, https://iaeimagazine.org/columns/photovoltaic/pv-systems-math-sample-calculations/, fetched 28 Sep 2026
bussmann-2005-xfmr — Cooper Bussmann, Fuse Application Guide, transformer protection (©2005), https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/solution-center/bus-ele-tech-lib-transformer-protection.pdf, fetched 28 Sep 2026
ecm-2020-loadcalc1 — EC&M, Mike Holt, "Load Calculations — Part 1", 26 Mar 2020 (NEC 2020; 220.14(I) and Table 220.44 unchanged in 2023), https://www.ecmweb.com/national-electrical-code/code-basics/article/21127208/load-calculations-part-1, fetched 28 Sep 2026
ecm-2025-feeders — EC&M, Mike Holt, "NEC Requirements for Feeders", 13 Jun 2025, https://www.ecmweb.com/national-electrical-code/code-basics/article/55292492/nec-requirements-for-feeders, fetched 28 Sep 2026
cfr-1910-137 — 29 CFR 1910.137, Electrical protective equipment, Tables I-4 and I-5 (rule values, read from the regulation text), https://www.law.cornell.edu/cfr/text/29/1910.137, fetched 28 Sep 2026
osha-1926-404 — OSHA 29 CFR 1926.404(b)(1)(iii)(D), assured equipment grounding conductor program test intervals (rule values), https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.404, fetched 28 Sep 2026
osha-1926-p-appb — OSHA 29 CFR 1926 Subpart P Appendix B, Table B-1 Maximum Allowable Slopes (rule values), https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926SubpartPAppB, fetched 28 Sep 2026
osha-1926-l-appa — OSHA, 29 CFR 1926 Subpart L, (Non-mandatory) Appendix A "Scaffold Specifications": ¶1(b)(i), the table for 2 × 10 in. (nominal) or 2 × 9 in. (rough) solid sawn wood planks, and ¶1(c), light-, medium- and heavy-duty loads and the one-person load. https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926SubpartLAppA, fetched 28 Sep 2026
cfr-1926-451 — 29 CFR 1926.451(a)(1) (each scaffold and component supports "its own weight and at least 4 times the maximum intended load applied or transmitted to it") and (c)(1) (a height to base width ratio of more than four to one restrained from tipping), as published by Cornell LII: https://www.law.cornell.edu/cfr/text/29/1926.451, fetched 28 Sep 2026; (a)(1) re-read 4 Oct 2026
vcmwd-std-5-2 — Valley Center Municipal Water District, Standard Specifications, Section 5.2 Thrust Restraint and Anchor Blocks (rev. March 2020): Table 5.2.1 thrust from the hydrostatic test pressure by pipe and fitting (8 in C900, OD 9.05 in, 250 psi: 16,082 / 22,743 / 12,308 / 6,275 / 3,153 lb for a dead end and 90°, 45°, 22½°, 11¼° bends; 12 in C900, OD 13.2 in, 250 psi, 90°: 48,383 lb; 24 in C905 Class 165, OD 25.8 in, 215 psi: 112,400 lb dead end, 158,958 lb 90°); Table 5.2.2 "Muck, peat, etc." 0 lb/ft². https://www.vcmwd.org/pdf/eng_std/SECTION_2_DESIGN/5_WaterPipeline/5.2_ThrustRestraint&AnchorBlocks_PUBL.PDF, fetched 4 Oct 2026
servicewire-max-tensions — Service Wire Co., Max Pulling Tensions (reference document; rule values): "Tmax = k x n x CA" with k 0.008 copper and 0.006 aluminum; "Tmax should not exceed 6,000 lb. for a single conductor cable. Tmax should not exceed 10,000 lb. for 2 or more conductors."; a basket grip "should not exceed 1,000 lb. or the value determined in the above formula, whichever is smaller." https://www.servicewire.com/ServiceWire/ReferenceDocs/Products/MaxPullingTensions.pdf, fetched 4 Oct 2026
cfr-1910-184-2004 — 29 CFR 1910.184 (2004 edition, govinfo), Table N-184-20, the 1 in. row: 1,000 lb vertical, 750 lb choker, and 2,000 / 1,700 / 1,400 / 1,000 lb in a basket at vertical / 30° / 45° / 60°; "All angles shown are measured from the vertical." https://www.govinfo.gov/content/pkg/CFR-2004-title29-vol5/pdf/CFR-2004-title29-vol5-sec1910-184.pdf, fetched 4 Oct 2026
meyerfire-2024-nfpa291 — MeyerFire, "How to Create Flow Test Artificial Drop of 10%" (26 Jun 2024), quoting NFPA 291 (a recommended practice) 4.4.6: "sufficient discharge should be achieved to cause a drop in pressure at the residual hydrant of at least 10 percent", https://meyerfire.com/daily/how-to-create-flow-test-artificial-drop-of-10, fetched 4 Oct 2026
nd-70e-shock — University of Notre Dame Risk Management, "AC Current Shock Protection Boundaries" (NFPA 70E shock table, numbered 130.4(D)(a) before 2021): "Less than 50 V — Not Specified"; "50 V to 150 V — 3 feet, 6 inches — Avoid Contact", https://riskmanagement.conductor.nd.edu/assets/445151/ac_current_shock_protection_boundaries.pdf, fetched 4 Oct 2026
uconn-70e-2024 — University of Connecticut EHS, arc-flash table adapted from NFPA 70E-2024: "Arc-resistant equipment 1 kV through 15 kV with the following parameters: DOORS CLOSED and SECURED; with an available fault current and a fault clearing time that does not exceed the arc-resistant rating of the equipment", https://ehs.media.uconn.edu/wp-content/uploads/sites/3238/2025/04/ArcFlashBoundaries2024Access.pdf, fetched 4 Oct 2026
cfr-1910-95 — 29 CFR 1910.95(c)(1), as published by Cornell LII: a hearing conservation program "whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels ... or, equivalently, a dose of fifty percent", https://www.law.cornell.edu/cfr/text/29/1910.95, fetched 4 Oct 2026
cdc-niosh-noise — CDC / NIOSH, "Understand Noise Exposure": the REL is 85 dBA over an eight-hour shift; "If workers are repeatedly exposed to noise at or above the REL, employers must provide a hearing loss prevention program." https://www.cdc.gov/niosh/noise/prevent/understand.html, fetched 4 Oct 2026
ecm-2016-workspace — EC&M (ecmag.com), C. R. Miller, "General Installation Requirements, Part XIX", 15 Aug 2016, on NEC 110.26(A)(2): "the work space shall permit at least a 90-degree opening of equipment doors or hinged panels" (NEC edition not stated), https://www.ecmag.com/section/codes-standards/general-installation-requirements-part-xix, fetched 4 Oct 2026
ecm-holt-2016-ac — EC&M, Mike Holt, 'Properly Sizing Conductors and Protective Devices for A/C and Refrigeration Equipment' (16 May 2016): "18A × 1.25 = 22.50A. A 12 AWG conductor is rated 25A at 75°C"; "You can use a 30A or 40A overcurrent device to protect a 12 AWG conductor for an air-conditioning circuit. See Sec. 240.4(G)". https://www.ecmweb.com/national-electrical-code/code-basics/article/20901145/properly-sizing-conductors-and-protective-devices-for-a-c-and-refrigeration-equipment, fetched 4 Oct 2026
ecm-holt-2022-ac — EC&M, Mike Holt, 'Stumped by the Code? NEC Requirements for Sizing Branch Circuit Conductors for a Single Motor-Compressor' (5 Apr 2022, 2020 NEC): "Branch-Circuit Conductor = 18A × 125% = 22.50A. Use a 10 AWG conductor rated 30A at 60°C". https://ecmweb.com/national-electrical-code/qa/article/21237517/stumped-by-the-code-nec-requirements-for-sizing-branch-circuit-conductors-for-a-single-motor-compressor, fetched 4 Oct 2026
myelectrical-ups-2012 — myElectrical, Steven McFadyen, 'UPS Battery Sizing' (8 Apr 2012): 300 kVA, 0.8 PF, 94 % efficiency, 240 cells; "watt/cell (three banks in parallel) = 1063/3 = 354". https://myelectrical.com/notes/entryid/164/ups-battery-sizing, fetched 4 Oct 2026
niosh-94-110-2021 — NIOSH Applications Manual for the Revised NIOSH Lifting Equation, Publication 94-110 (revised September 2021), 1.3.5.3: "Lifting above the maximum frequency results in a RWL of 0.0." https://stacks.cdc.gov/view/cdc/110725/cdc_110725_DS1.pdf, fetched 4 Oct 2026
niosh-94-110-2021-t5 — NIOSH Applications Manual for the Revised NIOSH Lifting Equation, Publication 94-110 (revised September 2021), Table 5 (FM), more than 2 but not more than 8 hours, V < 30 in: 8 lifts/min ".18", 9 lifts/min ".00"; 1.3.5.3: "Lifting above the maximum frequency results in a RWL of 0.0. (Except for the special case of discontinuous lifting discussed above, where the maximum frequency is 15 lifts/minute.)" https://stacks.cdc.gov/view/cdc/110725/cdc_110725_DS1.pdf, fetched 4 Oct 2026
viking-f070309 — Viking Group, Form F_070309 (18 May 2009): the 6 in. Model D-1/G-1 check valve's friction loss as 20 ft of 6 in. Schedule 40 pipe (id 6.065 in.), C = 120, with the Hazen–Williams formula printed on the chart. https://vikinggroupinc.com/sites/default/files/migrated/070309.pdf, fetched 28 Sep 2026
viking-f062809 — Viking Group, Form F_062809 (18 May 2009): the 2 in. spring-loaded check valve's friction loss as 8 ft of 2 in. Schedule 40 pipe (id 2.067 in.), C = 120, formula printed on the chart. https://vikinggroupinc.com/sites/default/files/migrated/062809.pdf, fetched 28 Sep 2026
viking-martorano-2008 — Scott Martorano, CFPS, "Hydraulic Calculations", Viking technical article, August 2008, pp. 1 and 3. https://www.vikinggroupinc.com/sites/default/files/documents/Hydraulic%20Calculations.pdf, fetched 28 Sep 2026
jlc-2017-stairs — Tim Healey, "Stair Stringers: Calculation and Layout", Journal of Light Construction, 29 Mar 2017. https://www.jlconline.com/?p=76849, fetched 28 Sep 2026
maine-doe-rafters — Jason Merritt and Erica Gallant, "Calculating Common Rafters", Math-in-CTE lesson C16, Maine Department of Education (undated). https://www.maine.gov/doe/sites/maine.gov.doe/files/inline-files/CTE%20-%20Math%20in%20CTE%20Construction%20Roof%20Rafters%20-%2002.18.2025.pdf, fetched 28 Sep 2026
bia-tn3c-2026 — Brick Industry Association, Technical Note 3C, "2022 TMS 402/602 Building Code and Specification – Anchored Veneer", July 2026, read in full: Table 2 (p. 5), "Prescriptive Basic" "2.67 ft² (0.248 m²)" and "24 in. (610 mm)", "Prescriptive Enhanced" "1.78 ft² (0.165 m²)" and "16 in. (406 mm)"; "Veneer ties must be located within 12 in. (305 mm) of unsupported edges such as vertical corners, openings and movement joints, except at the top of the veneer and support locations." (p. 5). https://www.gobrick.com/media/file/TN%203C_2022%20TMS%20402%20602%20Building%20Code%20and%20Specification%20-%20Anchored%20Veneer.pdf, fetched 28 Sep 2026 and 7 Oct 2026
wheatland-std-pipe — Wheatland Tube, "Standard Pipe" (WST-042125), ASTM A53 / ASME B36.10M, Schedule 40 rows for NPS 2, 4 and 6. https://www.wheatland.com/wp-content/uploads/2017/12/Standard-Pipe-Brochure-2.pdf, fetched 28 Sep 2026
ecm-2020-loadcalc2 — EC&M, Mike Holt, "Load Calculations — Part 2", 17 Apr 2020 (2020 NEC), dwelling optional method. https://ecmweb.com/national-electrical-code/code-basics/article/21129110/loads-calculations-part-2, fetched 28 Sep 2026
ecmag-2010-lii — Electrical Contractor, Charles R. Miller, "Branch-Circuit, Feeder and Service Calculations, Part LII", 15 Jun 2010, existing dwelling unit (220.83). https://www.ecmag.com/magazine/articles/article-detail/codes-standards-branch-circuit-feeder-and-service-calculations-part-lii, fetched 28 Sep 2026
ecmag-2011-lix — Electrical Contractor, Charles R. Miller, "Branch-Circuit, Feeder and Service Calculations, Part LIX", 15 Jan 2011 (2011 NEC), school optional method (220.86). https://www.ecmag.com/magazine/articles/article-detail/codes-standards-branch-circuit-feeder-and-service-calculations-part-lix, fetched 28 Sep 2026
ecmag-2011-lxi — Electrical Contractor, Charles R. Miller, "Branch-Circuit, Feeder and Service Calculations, Part LXI", 15 Mar 2011 (2011 NEC), restaurant optional method (220.88). https://www.ecmag.com/magazine/articles/article-detail/codes-standards-branch-circuit-feeder-and-service-calculations-part-lxi, fetched 28 Sep 2026
lex-cords — Lex Products, "Table 400-5(a). Allowable Ampacity for Flexible Cords and Cables" (undated; the pre-2002 table number), columns A (3 current-carrying conductors) and B (2). https://lexproducts.com/technical/portable-cord, fetched 28 Sep 2026
ecm-2015-cords — EC&M, Mike Holt, "Code Q&A: Allowable Ampacity for Flexible Cords", 19 Aug 2015: adjustment for more than three current-carrying conductors. https://ecmweb.com/national-electrical-code/qa/article/20900642/code-qa-allowable-ampacity-for-flexible-cords, fetched 28 Sep 2026
abb-reliagear-2022 — ABB, ReliaGear Low Amp Busway Technical Guide 1VA0098202-TG Rev. B, July 2022, p. 9, Table 1 (R and X in mΩ per 100 ft line-to-neutral; line-to-line drop per 100 ft at rated load). https://library.e.abb.com/public/cef2d62d43d045ae986ed5796581b106/1VAL098202-TG_RevB_ReliaGearLowAmpBusway-TechGuide_digital.pdf, fetched 28 Sep 2026
cornell-zonal — Cornell University, DEA 3500 "Zonal Cavity" lighting notes (undated): 30 × 20 ft room worked example. https://ergo.human.cornell.edu/studentdownloads/DEA3500notes/Lighting/zonalcavitynotes.html, fetched 28 Sep 2026
ecm-2023-emt-bends — EC&M, Mike Holt, "Code Q&A: NEC Requirements for EMT Bends", 25 May 2023 (358.26). https://www.ecmweb.com/national-electrical-code/qa/article/21266219/code-qa-nec-requirements-for-emt-bends, fetched 28 Sep 2026
ecm-2023-conductor-id — EC&M, Mike Holt, "Code Q&A: NEC Requirements for Conductor Identification", 23 Mar 2023 (200.6, 250.119, no required phase colours). https://ecmweb.com/national-electrical-code/qa/article/21262479/code-qa-nec-requirements-for-conductor-identification, fetched 28 Sep 2026
ecmag-2015-110-15 — Electrical Contractor, Charles R. Miller, "General Installation Requirements, Part X", 15 Nov 2015 (110.15, the high leg orange). https://www.ecmag.com/magazine/articles/article-detail/codes-standards-general-installation-requirements-part-x, fetched 28 Sep 2026
se-fa102254 — Schneider Electric FAQ FA102254, "What is the standard method for circuit numbering in panelboards?" (published 10 Mar 2004, modified 22 Apr 2026). https://www.se.com/us/en/faqs/FA102254, fetched 28 Sep 2026
ecmag-2022-panelboards — Electrical Contractor, Mark C. Ode, "Be Specific When It Comes to Panelboards", 15 May 2022 (2020 NEC, 408.3(E)(1)). https://www.ecmag.com/magazine/articles/article-detail/be-specific-when-it-comes-to-panelboards, fetched 28 Sep 2026
omada-2026-poe — TP-Link Omada, Laviet Joaquin, "PoE Switch Guide: Standards, Power Budget and Planning for Business", 4 Aug 2026 (802.3af/at/bt power table; the 250 W budget example). https://www.omadanetworks.com/ph/blog/2627/poe-switch-guide-standards-power-budget-and-planning-for-business/, fetched 28 Sep 2026
nema-types-2005 — NEMA, "NEMA Enclosure Types", November 2005: the Type 4X and Type 6P definitions. https://nema.org/docs/default-source/products-document-library/nema-enclosure-types.pdf, fetched 28 Sep 2026
sx-tg016-2020 — Superior Essex Communications, "How to Calculate Conduit Fill", Technical Guideline TG016 Rev. 6, 30 Jul 2020, Example 1. https://archive.superioressexcommunications.com/wp-content/uploads/2020/02/TG016-Conduit-Fill-Requirements.pdf, fetched 28 Sep 2026
iac-appendix-b — "Modern Industrial Assessments", Appendix B "Thermodynamic Analysis", pp. 403–404 (DOE Industrial Assessment Centers site): 35 °F saturated air heated to 100 °F. https://iac.university/technicalDocs/industr/appendixb.pdf, fetched 28 Sep 2026
ehazard-2024-torque — e-Hazard, Ken Sellars, "Let's Talk Torque…Again!", 21 Feb 2024 (UL 486A-B, 3/8 in. recessed hex drive). https://e-hazard.com/lets-talk-torque-again/, fetched 28 Sep 2026
cfr-1926-502 — 29 CFR 1926.502(d)(16)(iii) and (iv), personal fall arrest systems (free fall 6 ft; deceleration distance 3.5 ft), as published by Cornell LII: https://www.law.cornell.edu/cfr/text/29/1926.502, fetched 29 Sep 2026
interpower-nema — Interpower, "Plugs and receptacles by rating" NEMA configuration chart (Rev. 10-17). https://blog.interpower.com/hubfs/Interpower_March2018/Docs/NEMA-w-cable-poster.pdf, fetched 29 Sep 2026
eaton-2014-scc — Eaton, "Short-Circuit Current Calculations" (©2014, from p. 237): the point-to-point method; "UL 1561 listed transformers 25kVA and larger have a ± 10% impedance tolerance … for high end worst case, multiply %Z by .9"; System A (1500 kVA, 480 V, 3.5 %Z), fault X1: 1,804.3 A full load, multiplier 31.746, 57,279 A; motor contribution 7,217 A, 64,496 A in all. Fault X2 (25 ft of six 500 kcmil copper sets per phase, steel conduit): 55,137 A, excluding the motor contribution. https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/solution-center/bus-ele-tech-lib-electrical-formulas.pdf, fetched 29 Sep 2026
liebherr-2024-wind — Liebherr-Werk Ehingen, "Influence of Wind on Crane Operation" (lwe-P403.EN.12.2024): load charts use EN 13000's load reference of 1.2 m² of wind area (projected area × cD) per tonne of hoist load (hook block and lifting gear included); a larger area lowers the permissible wind: vmax = vmax_TAB × √(1.2 m²/t ÷ (AW / mH)). Examples: 65 t, 280 m², 11.2 m/s → 5.9 m/s; 85 t, 60 m², 9 m/s → unchanged. https://assets-cdn.liebherr.com/versions/61d28acb-d5bc-4fad-8941-6b243f024396/original, fetched 4 Oct 2026
falltech-2026-clearance — FallTech, "Fall Clearance 101: How to Calculate Safe Distances" (Andrew Montiveo, 10 Apr 2026): an energy-absorbing lanyard, measured "from the connected anchor point": 6 ft lanyard + 3½ ft deceleration + 1 ft harness stretch + 5 ft D-ring height + 1½ ft safety factor = 17 ft; for an SRL the clearance is measured from the walking-working surface (its example: 3½ ft arrest + 1 ft stretch + 1½ ft safety factor + 4 ft swing fall = 10 ft). https://www.falltech.com/blog/fall-protection-guides-resources/fall-clearance-how-to-calculate-safe-distances, fetched 4 Oct 2026
gorbel-srl-clearance — Gorbel, "Fall Clearance Calculation Using an SRL" (Tether Track): "Self Retracting Lanyard Length = 18" (typical)" (read here as the anchor to the D-ring) + "Worker Height (standing)" 60 in (read here as the D-ring to the feet) + free fall 24 in + deceleration 42 in (Gorbel's OSHA / typical values) + harness stretch 12 in + safety factor 24 in = 180 in, a 15 ft anchor height. https://www.gorbel.com/resources/products/TetherTrack/Documents/Tether%20Track%20Fall%20Clearance%20calculation.pdf, fetched 4 Oct 2026
ecm-dedad-2001-pulling — EC&M, John DeDad, "Simple Calculations for Cable Pulling" (1 Nov 2001): three 500 kcmil cables, 1.60 in OD, 2.2 lb/ft, in 5 in GRS (ID 5.07 in), μ 0.5, cradled; "W = 1.28"; jam "1.05 x (5.07 in. ÷ 1.60 in.) = 3.33"; "10 ft x 6.6 lb/ft x 0.5 x 1.28 = 42 lb", 75 ft 317 lb, "635 ft x 6.6 lb/ft x 0.5 x 1.28 = 2,682 lb", 30 ft 127 lb; "750 = {[(3 x 1.28) - 2] x 7,880} ÷ 3R", "R = 14,499 ÷ 2,250 = 6.44 ft". https://www.ecmweb.com/content/article/20896918/simple-calculations-for-cable-pulling, fetched 5 Oct 2026
iewc-pulling-tensions — IEWC Technical Guide, Pulling Tensions: "T (Cu) = Number of Conductors x circular mils x .008"; aluminum "0.006 times CMA". https://www.iewc.com/resources/technical-guide/pulling-tensions, fetched 5 Oct 2026
columbus-tdmis-3000 — City of Columbus, Division of Power, TDMIS 3000 Conduit (Issue 11/19), Table 3004-1 duct bank dimensions, Schedule 40 PVC: "1½ inch minimum separation between ducts (except 6 inch ducts which require 2 inches of separation) and 3 inches between the ducts and the surface"; 4 in ducts: Fig. 2 "W 16 ½ H 16 ½", Fig. 2A "W 28 ½ H 10 ½", Fig. 6 "W 22 ½ H 28 ½"; 6 in ducts: Fig. 1 "W 21 ¼ H 12 ¾", Fig. 2A "W 38 ½ H 12 ¾", Fig. 4A "W 38 ½ H 21 ¼" (rows and columns per figure read from W and H). https://www.columbus.gov/files/sharedassets/city/v/1/utilities/documents/power-tdmis/3000-conduit.pdf, fetched 5 Oct 2026
la-dnr-standalone-pv — Louisiana Department of Natural Resources, Stand-Alone PV Sizing Guide (worksheet example): "7463 watt-hours / 24 volts = 311 amp-hours"; "311 x (7 / .8) = 2721 amp-hours"; 12 V, 478 Ah batteries, 2 in series and 6 in parallel, 12 batteries, 2868 Ah, 68.8 kWh. https://www.dnr.louisiana.gov/assets/TAD/pdfs/STANDALONE_PV_Sizing_Guide.pdf, fetched 5 Oct 2026
caudill-battcon-2001 — Rick Caudill (Liebert), "Sizing, Specifying and Testing High Rate Batteries for UPS Application", BATTCON 2001 (year from the conference archive; not printed in the paper): 240 cells; "the best selection is 19 minutes to 1.68 volts per cell"; "A battery operating to 403V for 19 minutes demonstrates full capacity." https://www.battcon.com/4afc0e/globalassets/documents/battcon-static-assets/2001/sizing-specifying-and-testing-high-rate-batteries-for-ups-application.pdf, fetched 5 Oct 2026
doe-motor-load-factsheet — U.S. Department of Energy, Motor Challenge fact sheet "Determining Electric Motor Load and Efficiency": "469.7 x 37 x 0.763 x √3 / 1000 = 22.9 kW"; synchronous speeds at 60 Hz for 2/4/6/8/10/12 poles: 3600/1800/1200/900/720/600 rpm; slip "1800 – 1770". https://www.energy.gov/sites/prod/files/2014/04/f15/10097517.pdf, fetched 5 Oct 2026
etb-motor-torque — Engineering ToolBox, "Electric Motors - Torque vs. Power and Speed": "T = (100 hp) 63025 / (1000 rpm) = 6303 lbf in"; table at 1000 rpm: 1 hp 5.3, 10 hp 53, 100 hp 525 lbf ft. https://engineeringtoolbox.com/electrical-motors-hp-torque-rpm-d_1503.html, fetched 5 Oct 2026
wwe-frame-guide-2024 — WorldWide Electric, "Motor Frame Guide: Understanding NEMA and IEC Frame Numbers in Electric Motors" (11 Jul 2024): "a NEMA 324T frame motor has a shaft height of 32/4 or 8 inches". https://worldwideelectric.com/articles/motor-frame-guide-understanding-nema-and-iec-frame-numbers-in-electric-motors/, fetched 5 Oct 2026
pqblog-neutral-2021 — powerquality.blog, "Calculate Neutral Current in Dran-View 7" (19 Mar 2021): "five amps, eight amps and 10 amps"; "the square root of the following: (A^2 + B^2 + C^2 – AB – AC – BC)"; "The neutral current in the example is about 4.36 amps". https://powerquality.blog/2021/03/19/calculate-neutral-current-in-dran-view-7/, fetched 5 Oct 2026
aac-ac-magnitude — All About Circuits, Textbook Vol. II ch. 1, "Measurements of AC Magnitude": "For a sine wave, the RMS value is approximately 0.707 of its peak value"; "the average value so calculated is approximately 0.637 of its peak value"; "a form factor of 1.11 (0.707/0.636)". https://www.allaboutcircuits.com/textbook/alternating-current/chpt-1/measurements-ac-magnitude/, fetched 5 Oct 2026
redarc-inverter-draw — REDARC support, "How much power does an inverter draw" (updated 13 Nov 2025): "300W load at 24V → 300 ÷ 24 ÷ 0.85 = 14.7A"; at 12 V, 29.4 A. https://us.support.redarcelectronics.com/hc/en-us/articles/13783650432783-How-much-power-does-an-inverter-draw, fetched 5 Oct 2026
uky-ee461-lecture04 — University of Kentucky, EE 461 Lecture 4 (D. L. Lau), half-wave rectifier with a filter capacitor: "Vp = 10 V, f = 60 Hz, RL = 1 kΩ", "Desired ∆V = 1 V (10% ripple)", "C = 10 / (60×1000×1) = 167 µF". https://web.engr.uky.edu/~dllau/page0/ee461/lectures/Lecture04.pdf, fetched 5 Oct 2026
generac-mobile-sizing-2019 — Generac Mobile, Dave Murphy, "Basic Sizing for Mobile Generators" (Feb 2019): "100 hp * 6.3 kVA = 630 skVA required to start this motor across the line"; "a solid state soft starter with a 300% current limit setting would reduce our skVA from 630 across the line, down to 315 skVA". https://WWW.GENERAC.COM/globalassets/pdfs/industrial/whitepapers/basic-sizing-for-mobile-generators.pdf, fetched 5 Oct 2026
idc-motor-starting-sags — IDC Technologies, "Motor Starting Sags": wye-delta "starting current and starting torque is reduced to 33 percent of their values for full-voltage start." https://www.idc-online.com/technical_references/pdfs/electrical_engineering/Motor_Starting_Sags.pdf, fetched 5 Oct 2026
ecm-bey-2000 — EC&M, Larry A. Bey (Cummins Onan), "Sizing Gen-Sets For Large Motor Starting" (1 Feb 2000): autotransformer 65 % tap "(0.65) squared, or 0.42 times the starting kVA"; Example One: two 200 hp Code G motors (RkW 162.2, RkVA 178.2 each) and 100 kVA of lighting ("RkW = 100kVA x 0.95 PF = 95kW"); running load 420 kW, 457 kVA. https://www.ecmweb.com/basics/article/20885994/sizing-gen-sets-for-large-motor-starting, fetched 5 Oct 2026
leviton-captaincode-2017-517-16 — Leviton, Captain Code 2017 (NEC text © 2016 NFPA), 517.16(B)(1): "The equipment grounding conductor connected to the grounding terminals of isolated ground receptacles" "in patient care spaces shall be clearly identified along the equipment grounding conductor's entire length" "by green insulation with one or more yellow stripes"; the receptacles "connected to an insulated equipment grounding conductor in accordance with 250.146(D)". 2020: mypdh.engineer, 2020 NEC Significant Code Changes, 517.16(B)(1): "identified along the equipment grounding conductor's entire length by green insulation with one or more yellow stripes". 2023: Leviton, NEC Code Change Summary for Health Care Facilities (Q-899D, file name Q-899C, revised June 2024), 517.16 "Same as 2020." https://captaincode2017.leviton.com/node/149, fetched 29 Sep and 8 Oct 2026; https://mypdh.engineer/lessons/517-health-care-facilities-2/, fetched 29 Sep and 8 Oct 2026; https://leviton.com/content/dam/leviton/commercial-industrial/product_documents/take_one/NEC_Code_Change_Summary_for_Health_Care_Facilities_Q-899C.pdf, fetched 7 Oct 2026
caltrans-bdd-13-1 — Caltrans, Bridge Design Details 13.1 Reinforcement (Sep 2025): nominal diameter (in) and unit weight (lb/ft): #3 0.375 0.376; "#4 | 0.500 | 0.668"; #5 0.625 1.043; #6 0.750 1.502; #7 0.875 2.044; #8 1.000 2.670; #9 1.128 3.400; #10 1.270 4.303; #11 1.410 5.313; #14 1.693 7.650; #18 2.257 13.600. https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/bridgedesigndetails/chapter-12/202509bdd131reinforcement-a11y.pdf, fetched 5 Oct 2026
bia-tn10-2009 — Brick Industry Association, Technical Note 10, Dimensioning and Estimating Brick Masonry (Feb 2009), Table 4: "Modular … 675 (727)", "Utility … 300 (323)" units per 100 sq ft. https://gobrick.com/media/file/10-dimensioning-and-estimating-brick-masonry.pdf, fetched 5 Oct 2026
cmha-tek-04-02a — Concrete Masonry & Hardscapes Association, TEK 04-02A Estimating Concrete Masonry: "119 units per 100 ft2 (9.29 m2) of wall area" for 8 x 8 x 16 in. units, including 5 percent for waste and breakage. https://www.cmha.org/resource/tek-04-02a/, fetched 5 Oct 2026
quikrete-1102 — QUIKRETE Mortar Mix No. 1102 data sheet, yield: "80-lb. (36.3 kg) 12 37" (standard blocks and bricks laid per bag). https://quikrete.com/pdfs/data_sheet-mortarmix.pdf, fetched 5 Oct 2026
sulaimani-excavation — University of Sulaimani, S. Majid, excavation lecture notes: "Volume of loose clay = 100 X (1+0.3) = 130 m³" (100 bank m³ at 30 % swell). https://academics.su.edu.krd/public/profiles/sherzad.majid/teaching/teaching-427-42316-1684965543-1.pdf, fetched 5 Oct 2026
dewalt-dwht46031 — DeWalt DWHT46031 rafter square instruction manual, 9 in rise per foot: 20 ft building width (10 ft run) common rafter 12 ft 6 in, hip or valley 16 ft ⅛ in; Table 2 jack differences 1-8, 1-10½, 2-1 and 2-6 at 16, 18, 20 and 24 in centers; hip eave "24" x 1.28 = 30.72"". https://www.dewalt.com/GLOBALBOM/QU/DWHT46031/all/Instruction_Manual/EN/DWHT46031_RafterSquare.pdf, fetched 5 Oct 2026
dowtherm-sr1 — Dow, DOWTHERM SR-1 specification (Form 180-01274-402AMS), freezing points by volume: "26 10 214", "16 20 216", "10 25 218", "4 30 220", "-12 40 222", "-34 50 225" (°F, % by volume, boiling °F). https://www.deppmann.com/wp-content/uploads/2016/08/DowTherm-SR-1-Specification.pdf, fetched 5 Oct 2026
dowfrost-spec — Dow, DOWFROST specification (Form 180-01314-1101): "45.0 44.7 47.0 46.7 -26.7 (-16.1)" (wt %, vol %, freezing point °C with °F in parentheses). https://www.blichmannengineering.com/media/wysiwyg/pdf/Dowfrost_Spec.pdf, fetched 5 Oct 2026
etb-water-content — Engineering ToolBox, "Pipes and Tubes - Water Content": Schedule 40 steel ½ in 0.0158 and 1 in 0.0449 gal/ft; copper type L ½ in 0.0121 and 1 in 0.0429 gal/ft. https://engineeringtoolbox.com/water-content-steel-copper-pipes-tubes-d_1617.html, fetched 5 Oct 2026
etb-equivalent-diameter — Engineering ToolBox, "Equivalent Diameter - Rectangular vs. Circular HVAC Ducts": "12 x 45, 16 x 30, 20 x 24" → "24.1, 23.7, 23.9"; "1300 (0.59)" cfm in "12 x 14": "14.1" in, "0.15" in. per 100 ft. https://engineeringtoolbox.com/equivalent-diameter-d_443.html, fetched 5 Oct 2026
aisc-msc-1997-welding — Duane K. Miller, "Welding", AISC Modern Steel Construction (Jul 1997), Table 1, production welds with 1/8 in E7018 at 130 A: 1/4 in fillet "Electrode required 0.22 lb/ft", 5/16 in fillet "Electrode required 0.33 lb/ft". https://www.aisc.org/globalassets/modern-steel/archives/1997/07/1997v07_welding.pdf, fetched 5 Oct 2026
ecm-holt-2004-dwelling — EC&M, Mike Holt, "Dwelling Unit Feeder/Service Conductor Calculations" (1 Aug 2004), standard method: 1,500 sq ft; disposal 940 VA, dishwasher 1,250 VA, trash compactor 1,100 VA, water heater 4,500 VA, dryer 4,000 VA, cooktop 6,000 VA, two ovens 3,000 VA each; A/C "28 FL×230V=6,440 VA"; heat "3,000W×3 units=9,000W"; "The air conditioning load is smaller than the heat load, therefore it can be omitted."; no motor adder; "34,243VA total demand load", "I=34,243VA÷240V=143A". https://www.ecmweb.com/national-electrical-code/code-basics/article/20898089/dwelling-unit-feeder-service-conductor-calculations, fetched 7 Oct 2026
Reviewer policy
A tool is marked independently reviewed only when a named person, with the credential shown, has checked the encoded tables and the refusal logic against the edition named. Absent that, every result is a typical approach for field use that a licensed engineer confirms.

Anchors: /validation/#<tool> — every calculator's Code basis strip links here.

Schedule Health Check (DCMA 14-point)

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/dcma.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The DCMA 14-point assessment, as the guide defines it. Thresholds: logic ≤ 5 %, leads 0, lags ≤ 5 %, FS ≥ 90 %, hard constraints ≤ 5 %, high float ≤ 5 %, negative float 0, high duration ≤ 5 %, invalid dates 0, missed ≤ 5 %, CPLI ≥ 0.95, BEI ≥ 0.95; resources and the critical path test are reported, not scored. Hard constraints = must start/finish on, start/finish on or before. A 15th check for dangling SS/FF logic is added as information. A pass means the network is structurally sound, not that the plan is right. We count that an assessment ran and how many checks passed — never the schedule's contents.
External known-answer cases pinned in the harness
  • SCH-01 — Synthetic three-activity XER with no baseline → Empty-population and no-baseline checks read 'not assessed', never PASS (eval-2026-09-07; engine + pages)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Voltage Drop

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/voltage-drop.js, engine/code-basis.js · build 2026.10.13 · last change 2026-10-13
Scope and exclusions
Typical approach, not engineering. Resistance method: VD = 2 · I · L · R kft ⁄ 1000 for DC and single-phase, √3 · I · L · R kft ⁄ 1000 for three-phase, where L is one-way length in feet and R kft is the conductor resistance in Ω per 1,000 ft (Chapter 9 Table 8, 75 °C, corrected for temperature per Table 8 Note 2). Written per foot instead, R = K ⁄ cmil with K = 12.9 Ω·cmil/ft copper, 21.2 aluminum, and the same drop is VD = 2 · K · I · L ⁄ cmil (√3 · K · I · L ⁄ cmil three-phase) with no ÷ 1000 — the two forms differ only by R kft = 1000 · K ⁄ cmil. The circuit multiplier (2 or √3) appears once. The impedance method uses Chapter 9 Table 9 (three single conductors in conduit, 75 °C, 60 Hz): VD = √3 · I · L · Zₑ ⁄ 1000 for three-phase, and VD = 2 · I · L · Zₑ ⁄ 1000 for DC and single-phase — the circuit multiplier replaces √3, it is not applied on top of it — with Zₑ = R cos θ + X sin θ at your power factor (Table 9 Note 2) — R and X depend on conduit material; 700, 800, and 900 kcmil are not listed, so sizing steps past them. Sizing installs the larger of the voltage-drop minimum and the Table 310.16 ampacity minimum at the chosen temperature column (240.4(D) small-conductor caps; parallel sets from 1/0 AWG per 310.10(G)) — ambient correction, conductor-count adjustment, and continuous-load factors are on the Wire Sizing calculator. The 3 % and 5 % figures are NEC Informational-Note recommendations, not requirements. A licensed engineer confirms; nothing here is a seal or stamp.
External known-answer cases pinned in the harness
  • VD-01 — 120 V, 20 A, 100 ft, 12 AWG Cu, 75 °C → 7.902 V, 6.59 % (eval-2026-09-07; pages)
  • VD-02/03 — Change the load to 40 A after a result → Result marked stale until Calculate; then 15.80 V with an overload warning (eval-2026-09-07; pages)
  • VD-05 — Maximum length at 3 %, same circuit → 45.56 ft exact; 45 ft shown (rounded down) (eval-2026-09-07; engine + pages)
  • VD-06 — Re-enter the whole-foot maximum → Within 3 % (46 ft would be 3.03 %) (eval-2026-09-07; engine + pages + 108-case invariant sweep)
  • VDZ-01 — Effective impedance: 600 kcmil aluminum in PVC at 0.7 power factor (Table 9: R 0.036, XL 0.039 Ω per 1,000 ft) → Ze 0.0531 Ω per 1,000 ft to neutral (nec-handbook-2017-t9; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Ohm's Law

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/ohms-law.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
DC and resistive AC only. For AC loads with a power factor, use the Power calculator. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • OHM-01/02 — 120 V and 10 A; then a third, inconsistent 99 Ω → 12 Ω and 1,200 W; the third value is rejected (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Power

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/power.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Balanced loads, line-to-line voltage for three-phase. Voltage and current are RMS. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PWR-01 — Three-phase, 469.7 V, 37 A, PF 0.763 → 22.9 kW (within 0.5 %) (doe-motor-load-factsheet; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Power Triangle

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/power-triangle.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Magnitudes only. Lagging (inductive) and leading (capacitive) reactive power are not distinguished here. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • TRI-01 — 80 kW and 100 kVA → 60 kVAR; PF 0.8; 36.87° (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Power Factor Correction

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/pf-correction.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Sizing a bank, not designing one. Harmonics, resonance, switching, and motor self-excitation need an engineer's review. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PF-01 — 100 kW, PF 0.8 → 0.95 → 42.13 kvar; a 45 kvar bank gives PF 0.958 (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Conductor Size Converter

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/conversions.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Cross-section only. Ampacity does not convert with area — a metric cable's rating comes from its own standard. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Conduit Bend Total

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/bends.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Counting degrees, not designing the run. Laying out the bends themselves — offsets, saddles, stub-ups — is on Conduit Bending . Pull points, box fill at each, and the conductor's bending radius are separate checks. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BENDS-01 — The total of all bends, offsets included, between pull points → 360° at most (358.26) (ecm-2023-emt-bends; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Ampacity and Derating Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/ampacity.js, engine/conductors.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Ampacity under conditions of use, not a breaker size. NEC 2023 Table 310.16 basis with ambient correction, conductor-count adjustment, termination limits, and the small-conductor caps. Conductors in cable in thermal insulation and engineering-supervision methods are not applied. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • AMP-01 — 6 AWG Cu, 90 °C insulation, 75 °C terminal, 40 °C ambient, 6 CCC → 75 × 0.91 × 0.8 = 54.6 A; below the 65 A termination limit (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Wire Sizing Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/wire-sizing.js, engine/ampacity.js, engine/grounding.js, engine/voltage-drop.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Branch-circuit and feeder conductor sizing, NEC 2023 basis. 210.19(A)(1) / 215.2(A)(1) continuous-load factor, Table 310.16 with 310.15 correction and adjustment, 110.14(C) termination limits, 240.4(D) caps, 240.4(B) next-size-up, 310.10(G) parallel minimum. Motor, welder, capacitor, and tap-rule circuits have their own articles. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • WIRE-01 — 100 A continuous → 125 A design; 1 AWG Cu at 130 A; 125 A device; 6 AWG Cu EGC (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Conduit Fill Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/conduit-fill.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Fill, not pull. NEC 2023 Chapter 9 Tables 1, 4, 5, 8: conductor areas are the code's approximate values for round concentric-lay stranding (compact-stranded and cables differ — use the manufacturer's dimensions). Equipment grounding conductors count. Jam ratio, bends, and pulling tension are separate checks. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FILL-01 — Nine 12 AWG THHN in ½ EMT → 0.1197 in² of 0.304 in² — 39.4 %, within the 40 % allowance (eval-2026-09-07; engine)
  • FILL-02 — 3 × 12 THHN, 3 × 14 THW, 3 × 10 RHH (0.0437 in², Table 5 with outer covering), 3 × 6 XHHW, 1 × 8 bare solid → 0.4027 in² total (Chapter 9 Tables 5 and 8) (ecm-2011-chapter9; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Box Fill Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/box-fill.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Volume, not wiring space. NEC 2023 314.16: conductors that originate and end inside the box (pigtails, jumpers) do not count; conductors 12 in or shorter passing through a box with no splice are counted once; a looped unbroken conductor at least twice the 300.14 minimum counts twice — enter it as two. Boxes with dimensions marked on them use the marked volume. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BOX-01 — 14/3 NM to a 3-way switch and 12/2 NM to a receptacle, internal cable clamps, EGCs → 23.50 in³ (5 × 2.00 + 6 × 2.25); a 4 × 2⅛ square box (30.30 in³) meets it (ecm-2008-boxfill; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Cable Tray Fill Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/tray-fill.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Fill by NEC 2023 392.22, ladder / ventilated-trough / wire-mesh tray. Cable diameters come from the manufacturer's cut sheet. Solid-bottom, channel, and ventilated-channel trays, cables over 2000 V, and Type MV/TC-ER special rules are not covered; ampacity in tray is 392.80. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • TRAY-01 — Ladder tray: 1 × 3/C 500 kcmil (2.26 in.), 2 × 3/C 250 kcmil (1.76 in.), 4 × 3/C 4/0 (1.55 in.) → Sum of diameters 11.98 in.; at least a 12 in. tray (bline-tray-rules; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Conduit Bending Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/bending.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Centerline geometry, the way the field method assumes it. To total the bends between pull points against 360° / 270°, use Conduit Bend Total . Bend radius is neglected between marks (it cancels on offsets and saddles); take-up, gain, and shrink on a real bender come from its chart — use it for anything tighter than a hand bender. Typical approach for field use. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BEND-01 — 10 in offset at 30° → 20 in between bends; 2.679 in exact shrink (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Cable Pulling Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/pull.js, engine/conduit-fill.js, engine/conductors.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The hand method, conservatively applied. Every bend uses the exponential form; vertical bends and reel back-tension are simplified; cable weights, diameters, allowable tension, and sidewall limits come from the manufacturer. For long or heavy pulls use the cable maker's software and a licensed engineer's review. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PULL-05 — Basket grip on 3 × 6 AWG copper; pulling eye on 3 × 1000 kcmil copper and on one 1000 kcmil copper conductor → Basket: the smaller of 1,000 lb and 0.008 × cmil × 3 (630 lb); eye: 24,000 lb by formula capped at 10,000 lb; single: 8,000 lb capped at 6,000 lb (servicewire-max-tensions; engine)
  • PULL-03 — Three 500 kcmil (1.60 in OD, 2.2 lb/ft) in 5.07 in ID conduit, μ 0.5; straights of 10, 75, 635 and 30 ft; sidewall at 7,880 lb on a 6.44 ft radius → Cradled, Wc 1.28, jam ratio 3.33; 42 / 317 / 2,682 / 127 lb; 750 lb/ft (within 1 %) (ecm-dedad-2001-pulling; engine)
  • PULL-04 — Pulling eye on three 4/0 AWG copper conductors (211,600 cmil each, NEC Chapter 9 Table 8) → 3 × 211,600 cmil × 0.008 = 5,078 lb (iewc-pulling-tensions; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Pull Box Sizing Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/pull-box.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Box dimensions for conductors 4 AWG and larger (NEC 2023 314.28(A)). Raceway trade sizes drive the numbers, not conductor count; the box still needs the fittings to fit and the depth for bending. Splices, conduit bodies, and boxes with removable covers have their own provisions. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PULL-01 — Four trade size 3 raceways: two on the left, one on the right, one on the bottom → Straight pull 8 × 3 = 24 in.; angle (6 × 3) + 3 = 21 in.; answer 24 in. (ecm-2022-pullbox; engine)
  • PULL-02 — Trade sizes 2 and 3 on the left, 3 on the top, 2 on the right → Straight 8 × 2 = 16 in.; angle (6 × 3) + 2 = 20 in.; answer 20 in. (ecm-2022-pullbox; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Transformer Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/transformer.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 Table 450.3(B) — transformers 1000 V and less. Inrush and Article 450 over 1000 V are not covered. The 240.21(C) lines below the result are the tap-rule ratio FLOORS only — an intermediate minimum, not an installable secondary conductor; the conductor is sized separately for load, termination, and the secondary device. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • XFMR-01 — 75 kVA, 480/208 V, three-phase → 90.2 / 208.2 A; 225 A primary and 300 A secondary maxima (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Grounding Conductor Sizing Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/grounding.js, engine/conductors.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 Tables 250.122 and 250.66, as tables. Motor circuits (250.122(D)), parallel EGCs (250.122(F)), and the main/system bonding jumper (250.28(D), sized by 250.102(C)) are separate rules. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • GND-01 — 200 A device, copper EGC → 6 AWG Cu (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Cut List Optimizer

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/cutlist.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A cut list, not a bill of material. Pieces are finished lengths — put miters, couplings, and fitting take-outs into the lengths you enter. Package counts and prices are yours. Typical approach for shop and field use. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Wire Reel and Cut-Length Optimizer

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/reels.js, engine/cutlist.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Reels and cuts, not conductor sizing. Size the conductors first (Wire Sizing or Batch Sizing), then plan the reels. Put-up lengths and weights are the manufacturer's. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Buy Quantity Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Purchase quantities, not an estimate. Waste factors are starting points — set your own by material and by how the job is packaged. Prefab kits usually run lower waste than field cuts. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Procurement Lead-Time Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/leadtime.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A schedule of dates, not a promise from the vendor. Fabrication lead times come from the quote and change; review durations come from the contract. Re-run when either moves. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Working Space Checker (110.26)

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/clearance.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 110.26 for equipment likely to be worked on energized, 1000 V and below. Over 1000 V is 110.34; other spaces (equipment rooms, transformer vaults) have their own articles. Typical approach for field use; the AHJ decides. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • WS-01 — 300 V to ground, exposed live parts on both sides (condition 3) → 4 ft (ecm-2014-workspace; engine)
  • WS-02 — Equipment doors or hinged panels that can't open 90° → Not compliant: 110.26(A)(2) (ecm-2016-workspace; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Generator Sizing Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/generator.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A planning size, not a selection. Transient capability, derates, and nonlinear oversizing come from the manufacturer's data — enter theirs and this matches their software's first pass; frequency dip, voltage recovery, regenerative loads, and paralleling are theirs to model. Typical approach; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • GEN-01 — 100 hp NEMA Code G motor, across the line and on a soft starter (300 % current limit) → 630 skVA and 315 skVA (generac-mobile-sizing-2019; engine)
  • GEN-02 — Wye-delta starting → 33 % of the full-voltage starting current (idc-motor-starting-sags; engine)
  • GEN-03 — Autotransformer starter at the 65 % tap → 0.42 times the across-the-line starting kVA (ecm-bey-2000; engine)
  • GEN-04 — Bey's Example One: two 200 hp Code G motors (92 %, 0.91 PF) and 100 kVA of lighting → Running load 420 kW, 457 kVA (within 0.3 %) (ecm-bey-2000; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Panel Load Balance Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/panel.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Connected VA, linear loads. Demand factors (Article 220) and harmonic neutral currents are not applied. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BAL-01 — 600, 960 and 1,200 VA single-pole on A, B and C at 120 V (5, 8 and 10 A) → Neutral about 4.36 A (pqblog-neutral-2021; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

NFPA 70E Boundaries and PPE Category Calculator

Standard and edition
NFPA 70E, Standard for Electrical Safety in the Workplace 2024 — The 2027 edition is published and carries substantive changes to justified energized work. These tables are the 2024 edition. Use the edition your electrical safety program has adopted.
Engine
engine/nfpa70e.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NFPA 70E-2024, the table methods only. Shock boundaries above 750 V and the DC tables are not fully encoded — read them from the standard. The PPE category method is one of two permitted methods; the incident-energy analysis (engineer's arc-flash study) governs wherever it exists. Neither replaces the electrical safety program, the risk assessment, or the qualified person. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • ARC-01 — 4,160 V shock boundaries → Limited approach 5 ft fixed / 10 ft movable; restricted boundary directs to the current table (eval-2026-09-07; engine)
  • ARC-02 — 240 V panel, 100 kA, 1 s → Table method refused against the 25 kA / 0.03 s parameters (eval-2026-09-07; engine)
  • ARC-03 — 50 V AC shock boundaries → The 50–150 V row: limited approach 3 ft 6 in; restricted: avoid contact (nd-70e-shock; engine)
  • ARC-04 — Arc-resistant equipment 1–15 kV, doors closed: rated 25 kA with 30 kA available; rated 0.1 s with 0.3 s clearing; then within a 40 kA, 0.5 s rating → The table row doesn't apply when the fault current or the clearing time exceeds the gear's arc-resistant rating; within it, no PPE category (uconn-70e-2024; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

TRIR, DART, and Severity Rate Calculator

Standard and edition
OSHA 29 CFR 1910 (general industry) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/safety-stats.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Arithmetic on your OSHA 300 log, not recordability decisions. What counts as recordable, DART, or lost time follows 29 CFR 1904 and your safety manager's determination. EMR comes from your carrier's rating bureau. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • SAFE-01 — 3 DART cases, 2 recordables, 200,000 hours → Rejected — DART cases cannot exceed recordables (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Rubber Insulating Glove Class and Test Log

Standard and edition
ASTM D120, Rubber Insulating Gloves current
OSHA 29 CFR 1926 (construction) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/gloves.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A log and a class lookup, not a testing lab. Electrical testing is done by an accredited lab to ASTM F496; the record they return is the record of compliance. Typical approach; the electrical safety program governs. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • GLOVE-01 — Classes 00 to 4; 480 V and 7,501 V ac exposures; retest dates → Maximum use 500 / 1,000 / 7,500 / 17,000 / 26,500 / 36,000 V ac; retest 2,500 to 40,000 V ac; in service every 6 months, unissued within 12 months (cfr-1910-137; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Assured Equipment Grounding Conductor Program Log

Standard and edition
OSHA 29 CFR 1926 (construction) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/aegcp.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The assured equipment grounding conductor program, or GFCI — one or the other on every construction site (1926.404(b)(1)). The colour code is the site's convention, not OSHA's; the written program, the competent person, and the test records are what the inspector asks for. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • AEGCP-01 — Last test 15 Jan 2026; portable vs fixed and not exposed to damage → Next test within 3 months (15 Apr) or 6 months (15 Jul) (osha-1926-404; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Method of Procedure (MOP) Builder

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
page-local · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A method of procedure laid out the way a data-center operator expects it — purpose, scope, risk, prerequisites, PPE, hazards, numbered steps with verification and hold points, back-out, post-work checks, contacts, approvals. The content is yours; the approvals are signatures on paper. Typical structure; your site's change-management process governs. No word you type leaves your browser — we count that a MOP was laid out and its risk level only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Motor Circuit Calculator (Article 430)

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/motor.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 Article 430, continuous-duty motors on the table FLC. Wound-rotor, DC, synchronous, multispeed, low-speed, and VFD-fed motors (430.122 uses the drive's input current) size differently. The small-conductor limits of 240.4(D) don't apply: Table 240.4(G) sends motor-circuit protection to Article 430 (Parts II–VII), so the device comes from 430.52 (430.62 for a feeder). Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • MOTOR-01 — 25 hp, 460 V, three-phase, 32 A nameplate, inverse-time breaker → 34 A table FLC; 42.5 A conductors; 8 AWG Cu; 90 A device; 40 A overload (eval-2026-09-07; engine)
  • MOTOR-02/03 — Three-phase with the DC motor type → Refused — no result (Table 430.247 not encoded) (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Available Fault Current Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/fault.js, engine/impedance.js, engine/conductors.js · build 2026.10.13 · last change 2026-10-10
Scope and exclusions
Bolted fault current, planning grade: three-phase, or single-phase 3-wire. A single-phase transformer is computed line to line by the impedance method below with each run out and back; with a center tap, line to neutral too, at half the voltage with the transformer's R × 1.5 and X × 1.2 (the approximation Farrell and Valvoda give where the half-winding values aren't known, Consulting-Specifying Engineer, 2007), never below Bussmann's 1.5 × the line-to-line figure at the terminals. The utility's impedance is left out for single-phase, and motors are taken on the faulted leg. Uses the NEC Table 9 impedances the Voltage Drop tool uses. The transformer's %Z is taken at the low end of its tolerance (10 % by default: UL 1561 transformers 25 kVA and larger are ±10 %, ANSI two-winding ±7.5 %), as Eaton's point-to-point method does, and the nameplate figure is shown alongside. Eaton's highest case also multiplies by 1.1 for utility voltage (1.058 for 120 V lighting services); this tool doesn't. Conductor X is Table 9's; R is Table 9's 75 °C value corrected to 20 °C, because a cool conductor carries the most fault current (IEC 60909's basis for the maximum), with the Table 8 note's R2 = R1[1 + α(T2 − 75)], α 0.00323 copper and 0.00330 aluminum; the two are added as vectors. The point-to-point method adds its conductor constants (from IEEE 241) arithmetically, so downstream the two differ: on Eaton's 1500 kVA example (X/R 6.16 entered), with copper in steel conduit, this tool reads about 24 % higher at the end of 10 ft of #6, 3 % higher at the end of 50 ft of #12, and 2 % lower at the end of 150 ft of 4/0. The transformer-secondary figure is higher than any point below it. For arc flash, a lower current can be the worse case. A short-circuit study (with the utility's actual contribution, motor contributions by location, and arcing faults) is the engineer's deliverable and the basis for equipment ratings and the arc-flash labels. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FAULT-01 — System A, fault X1: 1500 kVA, 480 V, 3.5 %Z, infinite bus, %Z × 0.9 for the UL 1561 ±10 % tolerance; motors 4 × full load. The transformer secondary only: downstream points differ from the point-to-point method (see the tool's note) → 1,804.3 A full load; 57,279 A symmetrical RMS at the secondary; 64,496 A with the 7,217 A motor contribution (eaton-2014-scc; engine)
  • FAULT-02 — System A, fault X2: 25 ft of six 500 kcmil copper conductors per phase in steel conduit below X1 (%Z × 0.9, infinite bus, no motors), conductors at 20 °C, X/R 6.16 → 55,137 A by the point-to-point method; this tool's vector sum of Table 9 impedances lands within 1 % (54,853 A at X/R 6.16, an input Eaton's method doesn't use; −0.4 % to −0.7 % for any X/R from 3 to 10). It passes at 75 °C too (54,812 A): it pins the method's agreement, not the temperature change; downstream runs differ more (see the tool's note) (eaton-2014-scc; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Service and Feeder Sizing Calculator

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
NFPA 70, National Electrical Code 2026 — With NEC 2026 selected, a calculation applies these 2026 changes, each checked against the 2026 text on 26 Sep 2026: 2 VA/ft² (120.41), the dryer factors (Table 120.54), EVSE at its nameplate (120.57), the optional method's first 8 kVA with EVSE at 100 % (120.82), and 310.12's 75 °C conductors. Every other value is the 2023 one, and a line that still cites 220.x keeps its 2023 number. The edition your AHJ has adopted governs.
Engine
engine/feeder.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The conductor side of a service or feeder, from a load you've already calculated. Article 220 (demand factors, the standard and optional methods) is not applied here — bring the calculated load from the Dwelling, Multifamily, or Commercial Load tool. For one dwelling unit on 120/240 V, 310.12 lets the conductors carry 83 % of a 100–400 A rating. Services also need 230.42 / 230.79 minimums, 230.90 protection, and the utility's requirements. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FEED-01 — 100 A continuous + 100 A noncontinuous, copper, 75 °C terminals → 225 A; 4/0 AWG (230 A at 75 °C); 225 A device (ecm-2025-feeders; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Residential Load Calculator (NEC Article 220)

Standard and edition
NFPA 70, National Electrical Code 2023 — The 2026 NEC moved branch-circuit, feeder, and service load calculations out of Article 220 into the new Article 120, and changed values along the way (dwelling general lighting is 2 VA/ft², and the 125 % continuous multiplier came out of the load calculation itself). These engines are transcribed from the 2023 edition. The edition your AHJ has adopted governs — check it before you rely on a section number.
NFPA 70, National Electrical Code 2026 — With NEC 2026 selected, a calculation applies these 2026 changes, each checked against the 2026 text on 26 Sep 2026: 2 VA/ft² (120.41), the dryer factors (Table 120.54), EVSE at its nameplate (120.57), the optional method's first 8 kVA with EVSE at 100 % (120.82), and 310.12's 75 °C conductors. Every other value is the 2023 one, and a line that still cites 220.x keeps its 2023 number. The edition your AHJ has adopted governs.
Engine
engine/loadcalc.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC Article 220 (2023) or Article 120 (2026), applied line by line with the section named. Floor area, nameplates, and the heating and cooling control scheme are yours to confirm; jurisdictions amend Article 220 (EVSE and garages especially), and the utility and 230.79 set service minimums. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • DWELL-01 — EC&M's 1,500 ft² dwelling, optional method (220.82): heat pump 28 A at 240 V with 7 kW supplemental heat → 17,440 VA + 11,270 VA = 28,710 VA; 28,710 ÷ 240 = 120 A (ecm-2020-loadcalc2; engine)
  • EXIST-01 — Existing 1,500 ft² dwelling plus a 500 ft² addition, four small-appliance circuits, loads totalling 39,432 VA, 100 A service (220.83(A)); then a 7,200 VA air conditioner added (220.83(B)) → 20,573 VA → 86 A; then 27,773 VA → 116 A → 125 A (ecmag-2010-lii; engine)
  • DWELL-02 — EC&M's 1,500 ft² dwelling, standard method: 9,000 W of heat over a 6,440 VA air conditioner (220.60), disposal, dishwasher, compactor, water heater, dryer, cooktop and two ovens → 34,243 VA, 143 A; the A/C left out with no motor adder (ecm-holt-2004-dwelling; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Commercial Load Calculator (NEC Article 220)

Standard and edition
NFPA 70, National Electrical Code 2023 — The 2026 NEC moved branch-circuit, feeder, and service load calculations out of Article 220 into the new Article 120, and changed values along the way (dwelling general lighting is 2 VA/ft², and the 125 % continuous multiplier came out of the load calculation itself). These engines are transcribed from the 2023 edition. The edition your AHJ has adopted governs — check it before you rely on a section number.
Engine
engine/loadcalc.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 Article 220 Part III for a non-dwelling occupancy, line by line with the section named. Table 220.42(A) unit loads are minimums that already include the 125 % continuous multiplier; occupancy rows this tool has not verified against a published copy ask for the value from your code book. The optional methods for schools (220.86), new restaurants (220.88), and existing loads by demand data (220.87) are not applied here. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • COMM-01 — Office receptacles: 160 yokes → 28,800 VA; 10,000 VA at 100 % + 18,800 VA at 50 % = 19,400 VA (ecm-2020-loadcalc1; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Multifamily Load Calculator (NEC 220.84)

Standard and edition
NFPA 70, National Electrical Code 2023 — The 2026 NEC moved branch-circuit, feeder, and service load calculations out of Article 220 into the new Article 120, and changed values along the way (dwelling general lighting is 2 VA/ft², and the 125 % continuous multiplier came out of the load calculation itself). These engines are transcribed from the 2023 edition. The edition your AHJ has adopted governs — check it before you rely on a section number.
NFPA 70, National Electrical Code 2026 — With NEC 2026 selected, a calculation applies these 2026 changes, each checked against the 2026 text on 26 Sep 2026: 2 VA/ft² (120.41), the dryer factors (Table 120.54), EVSE at its nameplate (120.57), the optional method's first 8 kVA with EVSE at 100 % (120.82), and 310.12's 75 °C conductors. Every other value is the 2023 one, and a line that still cites 220.x keeps its 2023 number. The edition your AHJ has adopted governs.
Engine
engine/loadcalc.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC Article 220 (2023) or Article 120 (2026) for a multifamily feeder or service — Part III and the 220.84 optional method side by side. 220.84 needs one feeder per unit, electric cooking in every unit (or the 8 kW-per-unit exception, applied here), and heat or air-conditioning in every unit; house loads are Part III on top. Units are taken as identical — for a mixed building run each unit type through the Dwelling Load tool and sum by Part III. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • MFAM-01 — 12 units of 1,500 ft², optional method: range 14.4 kVA, dishwasher 1.5, water heater 4.0, dryer 4.5 kVA, heat 5.0 kVA (A/C 3.91 kVA smaller) → 460,800 VA connected × 41 % = 188,928 VA; 787 A at 240 V (ecm-2009-multifamily; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Optional Load Calculations — Schools, New Restaurants, Existing Loads (NEC 220.86, 220.88, 220.87)

Standard and edition
NFPA 70, National Electrical Code 2023 — The 2026 NEC moved branch-circuit, feeder, and service load calculations out of Article 220 into the new Article 120, and changed values along the way (dwelling general lighting is 2 VA/ft², and the 125 % continuous multiplier came out of the load calculation itself). These engines are transcribed from the 2023 edition. The edition your AHJ has adopted governs — check it before you rely on a section number.
Engine
engine/loadcalc.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
NEC 2023 Article 220 Part IV — the three optional methods that are not dwellings. Each stands in for Part III only where its section allows; the neutral is still 220.61. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • SCHOOL-01 — School, 750 kVA connected on 30,000 ft² (220.86) → 25 VA/ft² → 3 + 12.75 + 1.25 = 17 VA/ft² × 30,000 = 510 kVA (ecmag-2011-lix; engine)
  • REST-01 — Restaurants (220.88): 180 kVA all-electric; 394 kVA all-electric at 208Y/120 V; 455 kVA not all-electric → 144 kVA; 207 kVA, 575 A, 600 A service; 321 kVA (ecmag-2011-lxi; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Harmonic K-Factor Transformer Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/kfactor.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Selection guidance for K-rated transformers (UL 1561), not a harmonic study. Typical spectra vary by manufacturer and filtering; a measured spectrum at the point of connection is the real input. Typical approach; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

UPS Battery Sizing Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/ups.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A planning size for the battery plant, not a battery selection. Runtime at a given end voltage comes from the maker's constant-power tables (watts per cell), the UPS's DC cutoff, and its charger limits; lithium systems size on the BMS's usable capacity. Typical approach; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • UPS-01 — 300 kVA at 0.8 PF, 94 % inverter efficiency, 480 V bus (240 cells) → 1,063.8 W per cell (one bank); 354 W with three banks (myelectrical-ups-2012; engine)
  • UPS-02 — 240 cells discharged to 1.68 V per cell → 403 V (caudill-battcon-2001; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Rigging Calculator — Sling Tension, CG, Crane Chart, Outrigger Pads

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/rigging.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Static rigging arithmetic for the lift plan. ASME B30.9 slings, B30.26 hardware, B30.5 cranes, OSHA 1926 Subpart CC. The qualified rigger and the lift director own the lift: verified weight and CG, inspected slings and hardware at their tagged ratings, the crane's own chart and outrigger loads, wind, ground, and a critical-lift plan where the site requires one. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • RIG-01 — 10,000 lb, two legs at 30° from horizontal, 9,000 lb WLL → 10,000 lb per leg; 111 % — overload flagged (eval-2026-09-07; engine)
  • RIG-02 — One sling in a basket hitch, rated 1,000 lb vertical, at vertical, 30°, 45° and 60° from vertical; then 1,700 lb at 45° → Basket capacity 2,000 / 1,700 / 1,400 / 1,000 lb (2 × rating × cos θ gives 1,732 and 1,414 at 30° and 45°, within the table's rounding); 1,700 lb at 45° is over the rating (cfr-1910-184-2004; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Gear Rigging Path Check

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/gearpath.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Geometry and floor loading, not a rigging plan. Floor allowables come from the structural drawings (raised-floor panels and pedestals have their own ratings); turning at doors depends on the dolly and the crew. Typical approach for planning; the rigging contractor and the structural engineer confirm. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Truck Load Planner

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/truckload.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Cube, weight, and mode — not axle weights or securement. Payloads and positions are typical for the truck type; the carrier's equipment, the route's bridge and axle limits, and securement (FMCSA 393) are theirs. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Packing List and Bill of Lading Generator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/truckload.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
A packing list and a straight bill of lading, ready to print. Descriptions, weights, and classes are the shipper's declaration; hazardous materials need the DOT shipping description, which this form does not carry. No word you type leaves your browser — we count that a list was laid out only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Schedule Comparison (XER diff)

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/xerdiff.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
What changed between two exports, nothing more. Durations in the activity's calendar days, dates from the early dates (actuals where they exist), float from total float, lags in days on the calendar the schedule uses for lags. An activity matched without the same ID is a suggestion, never a certainty: the evidence is listed and one click undoes it. The change log is written from the comparison, line by line, in the order AACE RP 53R-06 asks an update narrative for changes. A change is a fact; whether it is a problem is the scheduler's call — pair it with the Schedule Health Check. We count that a comparison ran and its size — never the schedule's contents.
External known-answer cases pinned in the harness
  • DIFF-01 — Move A300 one day later → One changed activity, +1 day; nothing added or deleted (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Look-Ahead Schedule (from an XER)

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lookahead.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The schedule of record, sliced. In-progress activities lead week one; the rest land in the week their early start falls; 'waiting on' lists predecessors that are not complete. Level-of-effort and summary activities are excluded. Print it for the wall; the CSV goes to the crew planner. We count that a look-ahead ran and its window — never the schedule's contents.
External known-answer cases pinned in the harness
  • LOOK-01 — Three one-day activities in week one → Three tasks; two waiting; one-day durations (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Labor Histogram (from an XER)

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/histogram.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Units spread evenly across each assignment's window. P6 spreads on the resource calendar with curves; this is the straight-line planning view of the same numbers — close enough to see the peak and the gaps, not a substitute for P6's resource usage profile. FTE assumes 40 hours a week. Material resources are excluded. We count that a histogram ran — never the schedule's contents.
External known-answer cases pinned in the harness
  • LAB-01 — Three eight-hour assignments on a 40-hour week → 24 hours; 0.6 FTE; straight-line into week one (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

XER Viewer (P6 schedule Gantt)

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/gantt.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Your schedule stays on your device. The file is read in your browser and never uploaded or stored; closing the page forgets it. Dates are P6's: actual where recorded, otherwise the early (remaining) dates from the last schedule run. Total float is shown in days on each activity's own calendar; critical means total float of zero or less on an unfinished task or milestone. Nothing is rescheduled here. Share view copies a link that carries only the filters, grouping and time scale (never your search text); whoever opens it drops their own copy of the same XER. We count that a schedule was opened and its size band — never names, codes or dates.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Duct Bank Concrete Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/concrete.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Concrete encasement takeoff for the pour — envelope less the conduits. Cover, spacing, and burial depth come from the drawings and 300.5; the mix, slump, and dye from the spec. Typical approach for ordering; the pour ticket and the truck count are the field's. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • DUCT-01 — Schedule 40 PVC, 3 in cover: 4 in ducts at 1½ in spacing 2 × 2, 4 × 1 and 3 wide × 4 high; 6 in ducts at 2 in spacing 2 × 1, 4 × 1 and 4 wide × 2 high → 16½ × 16½, 28½ × 10½, 22½ × 28½, 21¼ × 12¾, 38½ × 12¾ and 38½ × 21¼ in (the table rounds up to the ¼ in) (columbus-tdmis-3000; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Concrete Pads, Bases, and Excavation Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/concrete.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Quantities for ordering, not structural design. Pad thickness, reinforcing, anchor embedment, and bearing are the engineer's; the shoring and the trench box are the competent person's. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • CONC-01 — 120 × 120 × 6 in, 10 % waste → 1.852 yd³ in place; 2.04 yd³ ordered (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Duct Sizer (Equal Friction) and Air Calculator

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/hvac.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Equal-friction sizing, the way a ductulator does it — a first pass, not a Manual D or a system design. Fittings, leakage, coil and filter drops, and the fan curve are the design; velocity limits here are noise guidance, not a spec. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • DSZ-01 — Rectangular ducts 12 × 45, 16 × 30 and 20 × 24 in → Round equivalents 24.1, 23.7 and 23.9 in (within 0.1 in) (etb-equivalent-diameter; engine)
  • DSZ-02 — 1,300 cfm in a 12 × 14 in duct → Equivalent 14.1 in; 0.15 in. of water per 100 ft (etb-equivalent-diameter; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Pipe Pressure Loss, Velocity, Slope, and Volume Calculator

Standard and edition
Hazen–Williams (water) — Valid for water in its normal temperature and velocity range. It is not a universal fluid equation; the C value is a project assumption.
Engine
engine/plumbing.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Hydraulics on nominal inside diameters — friction, velocity, slope, volume. Supply sizing by fixture units and drainage sizing by DFUs are code tables (IPC / UPC) not encoded here; the engineer's calc and the AHJ govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — No outside example in this tool's Hazen–Williams form (head loss per 100 ft) is pinned yet. The fire-protection form on Viking's charts (SPRK-01/02) reads about 2 % lower at the same flows, a difference between the two published forms, not an error (checked 29 Sep 2026).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Framing Calculator — Stud Walls, Rafters, Stairs

Standard and edition
International Residential Code 2021 — Stair and framing limits vary with local amendments; header sizing is structural design and is not encoded.
Engine
engine/framing.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Framing arithmetic — counts, lengths, and the stair rules. Header, rafter, and joist sizes come from the span tables (IRC / AWC) and the engineer where required; the code edition and the AHJ govern the stair limits. Typical approach for takeoff and layout. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • STAIR-01 — Total rise 30½ in., 10 in. treads → 4 risers of 7⅝ in.; 3 treads; 30 in. total run (jlc-2017-stairs; engine)
  • RAF-01 — 12 ft span, 5/12 pitch, run 6 ft (no ridge deduction, no overhang) → 13 in. per foot of run × 6 = 78 in. common rafter (maine-doe-rafters; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Structural Steel Weight Takeoff

Standard and edition
AISC Steel Construction Manual shape designations 15th ed. — Nominal weights for takeoff. HSS design wall thickness is 0.93 of nominal.
Engine
engine/steel.js, engine/procure.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Weight takeoff, not design. Member sizes come from the structural drawings; the fabricator's shop drawings and mill certs are the record. Typical approach for lifts, hauling, and the pour of the erection plan. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PIPE-01 — Schedule 40 pipe: NPS 2 (2.375 × 0.154 in.), NPS 4 (4.500 × 0.237 in.), NPS 6 (6.625 × 0.280 in.) → 3.66, 10.80 and 18.99 lb/ft (wheatland-std-pipe; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Masonry Takeoff — Brick, Block, Mortar, Grout, Rebar

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/masonry.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Takeoff for ordering — units, mortar, grout, steel. Reinforcing size and spacing, grout lifts, and inspection come from the structural drawings and TMS 402/602; lintels, control joints, flashing, and ties are extra. Typical approach; the supplier's yields and the engineer govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • MAS-01 — 100 ft² of wall, no waste, modular and utility brick → 675 modular, 300 utility (bia-tn10-2009; engine)
  • MAS-02 — 100 ft² of 8 × 8 × 16 CMU with 5 % waste → 119 units (cmha-tek-04-02a; engine)
  • MAS-03 — Mortar for 100 standard CMU in 80 lb bags → 100 ⁄ 12 = 8.3 bags; 8.0 to 8.7 within the printed rounding (11.5 to 12.5 blocks per bag) (quikrete-1102; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Fire Sprinkler Hydraulics — Demand, K-Factor, Friction, Layout

Standard and edition
NFPA 13, Installation of Sprinkler Systems — Density, coverage, and hose allowance are typed in from the edition in force on your job — they are not encoded. This is a first-look demand check, not a looped-grid hydraulic submittal.
Hazen–Williams (water) — Valid for water in its normal temperature and velocity range. It is not a universal fluid equation; the C value is a project assumption.
Engine
engine/fire.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Sprinkler arithmetic — K-factors, Hazen–Williams, elevation, a first-pass demand and layout. Densities, areas, coverages, spacing limits, and hose allowances come from NFPA 13 for the hazard and the head — enter them from the edition in force; the hydraulic calculation and the layout are the licensed designer's submittal, and the AHJ approves it. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • SPRK-01 — 20 ft of 6 in. Schedule 40 (6.065 in.), C = 120, at 400, 850, 1,300, 1,750, 2,200, 2,650 and 3,100 gpm → 0.13, 0.52, 1.14, 1.98, 3.03, 4.27 and 5.71 psi (viking-f070309; engine)
  • SPRK-02 — 8 ft of 2 in. Schedule 40 (2.067 in.), C = 120, at 40 to 360 gpm in 40 gpm steps → 0.14, 0.50, 1.05, 1.79, 2.71, 3.80, 5.05, 6.46 and 8.04 psi (viking-f062809; engine)
  • SPRK-03 — 0.2 gpm/ft² over 130 ft² on one K 8.0 head; a 30 ft water column → 26 gpm at (26 ÷ 8)² = 10.56 psi; 30 ft × 0.433 = 13 psi (viking-martorano-2008; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Jobsite Calculator — Feet, Inches, Fractions, Triangles, Circles, Running Tape

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/dimensions.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The jobsite calculator — feet, inches, and fractions, the way you say them. Type dimensions as 12' 6 3/8, 12'6-3/8, 6-1/2, 2.5', 150 (inches), or 100mm; results snap to the fraction you pick. Geometry only — no code rules involved. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Unit and Fastener Converter — Length, Pressure, Torque, Power, Inch and Metric Bolts

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/units.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Every unit a job site argues about, one box. Conversion factors are exact or NIST; thread data is ASME B1.1 / ISO 261 and hex sizes ASME B18.2.1 / ISO 4014 with the DIN 931 difference shown. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • CONV-01/02 — Blank value; then 1 in → mm → Blank is refused; 1 in = 25.4 mm (eval-2026-09-07; pages)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

AC to DC Converter — RMS, Peak, Rectifier Output, Inverter Battery Current

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/acdc.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
AC and DC, translated. Sine-wave relationships, rectifier arithmetic, inverter battery math, and power-factor equivalents — formulas only, no code rules. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • ACDC-01 — A sine wave of 100 V peak → RMS 70.7, average 63.7, form factor 1.11 (aac-ac-magnitude; engine)
  • ACDC-02 — A 300 W inverter load at 85 % efficiency on 12 V and on 24 V → 29.4 A and 14.7 A (redarc-inverter-draw; engine)
  • ACDC-03 — Half-wave rectifier, 10 V peak, 60 Hz, 10 mA load, 167 µF → Ripple about 1 V (uky-ee461-lecture04; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Torque Values and Verification Log — NEC Annex I (UL 486A-B) Tables I.2 and I.3

Standard and edition
NEC Annex I (UL 486A-B / 486E) torque tables NEC 2023 Annex I — Used only where the equipment manufacturer gives no torque value. A marked or listed instruction always wins.
Engine
engine/torque.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Torque values and the record that you applied them. The manufacturer's marked value always governs; NEC Informative Annex I (values reproduced in the NEC from UL 486A-486B with UL's permission) is the fallback when there is none — and 110.14(D) requires the torque tool. Nothing in the log leaves your browser. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • TORQ-01 — 3/8 in. recessed hex (Allen) drive → 375 lbf·in (42.4 N·m) (ehazard-2024-torque; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Insulation Resistance (Megger) Test Log — Temperature Correction, PI, DAR

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/insulation.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Insulation resistance, corrected and recorded. Readings are corrected to the 40 °C reference by the halving-per-10 °C rule of thumb; the pass mark is the minimum you enter from the spec, the manufacturer, or IEEE 43 — no licensed acceptance table is encoded. Test with the circuit de-energized, isolated, and discharged after the test. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Panel Circuit Directory and Label Generator — NEC 408.4(A)

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/directory.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The directory the inspector reads and the labels the next electrician thanks you for. 408.4(A): every circuit identified as to its clear, evident, and specific purpose — not by an occupant's name, and "spare" or "space" only for what is actually spare. Odd numbers down the left, even down the right, multi-pole devices on consecutive same-side positions, phases A-B-C by row. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • DIR-01 — Six single-pole circuits in a panelboard → Odd numbers on the left from 1 at the top, even on the right from 2 (se-fa102254; engine)
  • DIR-02 — Phase order of the positions down each side of a three-phase panelboard → A, B, C from top to bottom (408.3(E)(1)) (ecmag-2022-panelboards; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

EV Charger Circuit Calculator — NEC 625 Breaker, Wire, EGC, Service Load

Standard and edition
NFPA 70, National Electrical Code 2023 — The 2026 NEC moved branch-circuit, feeder, and service load calculations out of Article 220 into the new Article 120, and changed values along the way (dwelling general lighting is 2 VA/ft², and the 125 % continuous multiplier came out of the load calculation itself). These engines are transcribed from the 2023 edition. The edition your AHJ has adopted governs — check it before you rely on a section number.
Engine
engine/ev.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The branch circuit an EV charger actually needs — device, conductors, EGC, and the load it adds to the service. Article 625 with the 2023 220.57 service load and the EVEMS allowance. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • EV-01 — 48 A, 240 V → 60 A circuit; 6 AWG Cu; 10 AWG Cu EGC; 11.52 kW (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

PV String Sizing Calculator — NEC 690.7 Maximum Voltage, 690.8 Currents, 690.9 OCPD

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/pv.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The string that fits the inverter and the conductors that carry it. Article 690 with the module's own temperature coefficients; the site's record low and the equipment's voltage rating are yours to confirm. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PV-01 — 45 V Voc module, −0.36 %/°C, −10 °C, 11 in series → 1.126 × 45 = 50.67 V; 11 × 50.67 = 557.37 V (iaei-2019-pvmath; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

HVAC MCA and MOCP Calculator — NEC 440 Motor-Compressor Circuits

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/hvaccircuit.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The MCA and MOCP a nameplate prints — and where they come from. Article 440 for air-conditioning and refrigeration equipment with hermetic motor-compressors. With a motor-compressor in the circuit the small-conductor limits of 240.4(D) don't apply: Table 240.4(G) sends these conductors' protection to Article 440 (Parts III and VI), so the device comes from 440.22, not from the wire size (an 18 A compressor at 75 °C takes 12 AWG on a 30 A or 40 A device). Without a compressor (electric heat or fans alone) the limits stay. Typical approach for field use; the listed nameplate and a licensed engineer confirm design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • HVAC-01 — One 18 A motor-compressor, 75 °C terminations → 22.5 A → 12 AWG Cu (25 A at 75 °C) on a 30 A device, 40 A where 175 % won't start (240.4(G)) (ecm-holt-2016-ac; engine)
  • HVAC-02 — The same compressor, 60 °C terminations → 10 AWG Cu rated 30 A at 60 °C (ecm-holt-2022-ac; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Transformer Inrush Calculator — Will the Primary Breaker Hold on Energization?

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/inrush.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Will the primary breaker hold when the transformer is energized? An advisory check of the instantaneous region against the inrush multiple you enter; the manufacturer's inrush data and the device's time-current curve are the record. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • INRUSH-01 — 800 VA potential transformer, 2400 V primary, inrush 12 × for 0.1 s → IFL 0.333 A; inrush 4 A (bussmann-2005-xfmr; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Extension Cord and Flexible Cord Size Calculator — NEC Table 400.5(A)(1) Ampacity and Voltage Drop

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/cords.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Which cord for the load, and how far it can run. Table 400.5(A)(1) (verified) with the adjustment and ambient factors, plus the voltage drop that actually stalls the saw. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • CORD-01 — Flexible cord ampacity, 18 to 2 AWG, columns A (3 current-carrying) and B (2) → A: 7, 10, 15, 20, 25, 35, 45, 60, 80 A; B: 10, 13, 18, 25, 30, 40, 55, 70, 95 A (lex-cords; engine)
  • CORD-02 — More than three current-carrying conductors in a cord: 4–6, 7–9, 10–20 → × 0.80, 0.70, 0.50 (ecm-2015-cords; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Fiber Optic Link Loss Budget Calculator — TIA-568 Attenuation, Connectors, Splices

Standard and edition
TIA-568 optical fibre performance current — Generic cable and connector values — the reel sheet and the transceiver datasheet govern.
Engine
engine/lowvoltage.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The loss budget the tester will hold you to. TIA-568 maximum attenuation values as commonly published; your cable's and optics' data sheets give the real numbers. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FIBER-01 — 0.2 km multimode, 3 connectors, 1 splice, TIA-568 maximum values → 3.25 dB at 850 nm; 2.85 dB at 1300 nm (foa-lossbudget; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

PoE Power Budget Calculator — IEEE 802.3af/at/bt Classes per Switch

Standard and edition
IEEE 802.3af / at / bt Power over Ethernet current — PSE allocation by class; a certification tester is the record.
Engine
engine/lowvoltage.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Will the switch power everything you hang on it? IEEE 802.3af / at / bt class table (published), cable loss estimated from Cat 5e/6 DC resistance. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • POE-01 — PoE 802.3af, 802.3at and 802.3bt Types 3 and 4 → At the switch / at the device: 15.4 / 12.95, 30 / 25.5, 60 / 51, 90 / 71.3 W (omada-2026-poe; engine)
  • POE-02 — PoE+ ports at 30 W each on a 250 W switch budget → Fewer than nine can draw full PoE+ at the same time (omada-2026-poe; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Noise Dose and TWA Calculator — OSHA 1910.95 and NIOSH REL

Standard and edition
OSHA 29 CFR 1910 (general industry) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/safety.js · build 2026.10.13 · last change 2026-10-10
Scope and exclusions
The day's noise, added up the way OSHA does. Readings from a sound level meter (A-weighted, slow); dosimeters do this for you — this is for planning and for checking a task list. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • NOISE-02 — 90 dBA for 7.5 hours → Dose 94 %; TWA 89.6 dBA (wa-lni-noise; engine)
  • NOISE-04 — 2.85 h at 105 dBA and 6.65 h at 85 dBA → Dose 327 %; TWA 98.5 dBA (wa-lni-noise; engine)
  • NOISE-05 — 85 dBA for 8 hours (OSHA) → Dose 50 %: at the action level, so a hearing conservation program ("equal or exceed") (cfr-1910-95; engine)
  • NOISE-06 — 85 dBA for 8 hours (NIOSH REL) → Dose 100 %: at the REL, so a hearing loss prevention program ("at or above") (cdc-niosh-noise; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Fall Clearance Calculator — Lanyard or SRL, ANSI Z359 / OSHA 1926.502

Standard and edition
ANSI Z359 / OSHA 1926.502 fall protection current — The lanyard or SRL manufacturer's tested performance governs the clearance, not a generic allowance.
Engine
engine/safety.js · build 2026.10.13 · last change 2026-10-10
Scope and exclusions
The fall-clearance sum every competent person does before tying off. ANSI Z359 component distances and the OSHA 1926.502 limits; the lanyard's and SRL's labels and the manufacturer's clearance charts are the record. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FALL-01 — Personal fall arrest system limits → Free fall 6 ft at most; deceleration distance 3.5 ft at most (cfr-1926-502; engine)
  • FALL-02 — Shock-absorbing lanyard, measured from the anchor: 6 ft lanyard, 3½ ft deceleration, 1 ft harness stretch, 5 ft D-ring height, 1½ ft safety factor → 17 ft required below the anchor (falltech-2026-clearance; engine)
  • FALL-03 — SRL: Gorbel's 18 in SRL length (taken as the anchor above the D-ring), 60 in worker height (taken as the D-ring to the feet), Gorbel's 24 in free fall + 42 in deceleration entered as a 5½ ft arrest distance, 12 in stretch, 24 in safety factor → 15 ft anchor height required (gorbel-srl-clearance; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Heat Index and WBGT Calculator — NWS Heat Index Categories, Wet-Bulb Globe Temperature

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/safety.js · build 2026.10.13 · last change 2026-10-10
Scope and exclusions
How hot it really is to the body. The NWS heat index (its regression and categories) from temperature and humidity, or WBGT from meter readings; your heat-illness prevention program sets the work/rest and hydration rules. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • HEAT-01 — 96 °F, 65 % RH → Heat index 121 °F (eval-2026-09-07; engine)
  • NWS-HI — NWS published example → Matches the NWS table (nws-heat; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Concrete Formwork Lateral Pressure Calculator — ACI 347R Walls and Columns

Standard and edition
ACI 347R, Guide to Formwork for Concrete 2014 — SCC, admixtures, bottom pumping, and full-hydrostatic conditions fall outside the pressure formulas — check them before you set forms.
Engine
engine/civil2.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
What the forms have to hold back. The ACI 347R lateral-pressure relationships for walls and columns with the unit-weight and chemistry coefficients — the form designer's engineer confirms the ties, bracing, and the pour rate the crew can actually place. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FORM-01 — Wall, rate 4 ft/h, 60 °F, 150 pcf, Cw = Cc = 1.0 → 750 psf, one-half of the full fluid pressure (fcp-2010-formwork; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Thrust Block Calculator — Pipe Bends, Tees, and Dead Ends

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/civil2.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The concrete that keeps the joint from walking. Thrust from pressure and fitting geometry; bearing area from the soil the geotech gives you — restrained joints are the alternative where a block can't fit. A licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • THR-01 — 8 in C900 (OD 9.05 in) at a 250 psi test: dead end and 90°, 45°, 22½°, 11¼° bends; 12 in C900 (OD 13.2 in) at 250 psi, 90° → 16,082 / 22,743 / 12,308 / 6,275 / 3,153 lb; 48,383 lb (vcmwd-std-5-2; engine)
  • THR-02 — 24 in C905 Class 165 (OD 25.8 in) at a 215 psi test: dead end and 90° bend → 112,400 lb and 158,958 lb (vcmwd-std-5-2; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Rebar Takeoff Calculator — Bar Count, Laps, Sticks, and Tonnage for Slabs and Walls

Standard and edition
ASTM standard reinforcing bar data, nominal sizes and weights as tabulated in Caltrans Bridge Design Details 13.1, Table 13.1.1 (Sep 2025) — Nominal weights for takeoff.
Engine
engine/civil2.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The rebar order for a slab or wall, from the pattern on the drawings. Count, laps, sticks, and tonnage. Estimating aid — the placing drawings and the engineer's lap and cover requirements govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • RB-01 — Bar sizes #3 to #18 → Nominal diameters and unit weights as tabulated (e.g. #4: 0.500 in, 0.668 lb/ft; #18: 2.257 in, 13.600 lb/ft) (caltrans-bdd-13-1; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

NIOSH Lifting Equation Calculator — Recommended Weight Limit and Lifting Index

Standard and edition
NIOSH Revised Lifting Equation (Applications Manual) 1994
Engine
engine/lifting.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The NIOSH lifting equation, worked exactly as the Applications Manual does. Public-domain method (DHHS/NIOSH 94-110, revised 2021); multipliers to two places as the manual's worksheets use; verified against its worked examples. A lifting index over 1.0 is the redesign trigger, not a legal limit — there is no OSHA numeric lifting standard. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • LIFT-01 — 51 lb at the equation's ideal geometry, low frequency, good coupling → RWL 51 lb; LI 1.0; no 'largest penalty' named (eval-2026-09-07; engine)
  • LIFT-02 — A lifting frequency above the equation's maximum (16 lifts/min) → RWL 0.0: not acceptable at any load — redesign the task (niosh-94-110-2021; pages)
  • LIFT-03 — 8.5 lifts/min, more than 2 h and up to 8 h, V under 30 in (Table 5: .18 at 8 lifts/min, .00 at 9) → FM 0 and RWL 0.0 (past the column's maximum frequency, not interpolated toward the .00 row); 8 lifts/min keeps .18 (niosh-94-110-2021-t5; engine)
  • NIOSH-1 — Manual Example 1 (destination governs) → LI ≈ 3.0 (niosh-94-110; engine)
  • NIOSH-3 — Manual Example 3 → RWL 18.9 lb (niosh-94-110; engine)
  • NIOSH-6 — Manual Example 6 → RWL 16.4 lb (niosh-94-110; engine)
  • NIOSH-5 — Manual Example 5 (dish-washing trays), origin: H 20 in, V 44 in, D 37 in, A 30°, 5 lifts/min under 1 h, good coupling → RWL 14.4 lb (FM 0.80) (niosh-94-110; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Data Center Power and Cooling Calculator — IT kW to UPS, Feeders, Tons, CFM, GPM, PUE

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/dcpower.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
From the IT load to the whole chain — UPS, feeders, tons, CFM, GPM, unit count, and utility. Physics and standard conversions with the design ratios as inputs; a planning tool for the mission-critical wedge, not the equipment schedule. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • DC-01 — 1,000 kW IT, PUE 1.3, UPS 96 %, 200 kW cooling units, N+1 → 1,300 kW facility; 1,041.7 kW UPS input; seven cooling units (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

VFD Circuit Calculator — NEC 430.122 Drive Input Conductors, Motor Conductors, Device, EGC

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/dcpower.js, engine/ampacity.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The circuit ahead of a variable-frequency drive, sized to the drive, not the motor. Article 430 Part X; the drive's manual is the record for the device and any cable requirement. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — Not pinned: EC&M's example (Mike Holt, 2 Mar 2022, NEC 2020) sizes a 25 A drive input at 10 AWG by ampacity alone (35 A at 75 °C) and doesn't address 240.4(D) or (G). Unresolved: Table 240.4(G) lists Article 430 Parts II–VII and drives are Part X, but 430.130(A) sends a drive circuit's protection to 430.52(C) (Part IV), and many readers apply 240.4(G) to drives. Until that is settled this tool keeps the small-conductor limit and gives 8 AWG, the larger wire (HD, 4 Oct 2026; Table 240.4(G) read from the 2017 edition).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Motor Formulas Calculator — Synchronous Speed, Slip, Torque, Horsepower, Current, NEMA Frame

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/dcpower.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The motor arithmetic that isn't in Article 430. Speed, slip, torque, power, current, frame shaft height, and belt ratios — formulas only; conductor and device sizing live in the Motor Circuit tool. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • MF-01 — Synchronous speed at 60 Hz for 2, 4, 6, 8, 10 and 12 poles → 3600 / 1800 / 1200 / 900 / 720 / 600 rpm (doe-motor-load-factsheet; engine)
  • MF-02 — 4-pole motor at 1,770 rpm → Slip 1800 − 1770 = 30 rpm (30 ⁄ 1800 = 1.67 %) (doe-motor-load-factsheet; engine)
  • MF-03 — 100 hp at 1,000 rpm; 1, 10 and 100 hp at 1,000 rpm → 6,303 lbf·in; 5.3 / 53 / 525 lbf·ft (etb-motor-torque; engine)
  • MF-04 — NEMA frame 324T → Shaft height 8 in (wwe-frame-guide-2024; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Lighting Calculator — Lumen Method Fixture Count, Watts per Square Foot, Circuits

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/dcpower.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
How many fixtures, how many circuits, and the watts per square foot — the lumen method. Planning-grade; the lighting designer's point-by-point calculation and the energy code govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • LIGHT-01 — 30 × 20 ft room, 7.0 ft room cavity, 100 fc, 2 × 3,150 lm per luminaire, CU 0.48, LLF 0.78 → RCR 2.9; 60,000 lm needed ÷ 2,358.7 lm per luminaire = 25 luminaires (the source rounds; the tool rounds up, to 26, so the target is met) (cornell-zonal; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

NEMA Plug and Receptacle Chart — Straight-Blade and Locking Configurations by Voltage and Amps

Standard and edition
NEMA WD 6, Wiring Devices — Dimensional Specifications current
Engine
engine/reference.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The plug and receptacle chart, searchable. NEMA WD 6 straight-blade and locking configurations by voltage, amps, poles, and wires — with what each one is for. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • NEMA-01 — NEMA 5-15, 5-20, 6-15, 6-20, 6-30, L5-20, L6-30 → 15 A 125 V; 20 A 125 V; 15 A 250 V; 20 A 250 V; 30 A 250 V; 20 A 125 V locking; 30 A 250 V locking; each 3 wires (interpower-nema; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

NEMA Enclosure Type Selector and IP Rating Decoder — NEMA 250 and IEC 60529

Standard and edition
NEMA 250 enclosure types / IEC 60529 IP current — The NEMA-to-IP cross-reference runs one way only: a NEMA type can be said to meet or exceed an IP rating, but an IP rating cannot be converted back into a NEMA type.
Engine
engine/reference.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Which NEMA enclosure, and what the IP rating on the import actually means. NEMA 250 types with NEMA's own IEC 60529 cross-reference. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • ENCL-01 — NEMA Types 4X and 6P → 4X adds corrosion protection to Type 4 (hose-directed water); 6P: prolonged submersion at a limited depth, with corrosion protection (nema-types-2005; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Wire Color Code Reference — NEC, IEC, UK, Canada, Australia

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/reference.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Which wire is which — by code, and by habit. The NEC's required identifications and the North American conventions, alongside IEC, UK, Canadian, and Australian schemes for the imported equipment on the floor. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • COLOR-01 — United States: grounded, equipment grounding and ungrounded conductors → White or gray (200.6); green or green with a yellow stripe (250.119); no colour required for phase conductors (ecm-2023-conductor-id; engine)
  • COLOR-02 — High leg of a 4-wire delta → Orange, or other effective means (110.15) (ecmag-2015-110-15; engine)
  • COLOR-03 — United States: the equipment grounding conductor to isolated-ground receptacles → Green with one or more yellow stripes, required in health-care patient care spaces (517.16(B)(1)); convention elsewhere, where 250.146(D) requires an insulated EGC (leviton-captaincode-2017-517-16; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Communications Cable Conduit Fill Calculator — TIA-569 Fill for Cat 6A, Fiber, and Coax

Standard and edition
TIA-569 pathways and spaces current — Design-standard guidance for communications cable fill. It is not an NEC raceway requirement — do not confuse the two.
Engine
engine/fieldextras.js, engine/conduit-fill.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Conduit fill for Cat 6A, fiber, and coax — the pathway the tester never sees but the puller does. TIA-569 fill on the verified NEC raceway dimensions; cable diameters are typical, the data sheet governs. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • COMM-FILL-01 — Two RG-6 (0.30 in.) and two UTP (0.20 in.) cables; ¾ in. conduit (the tool uses EMT's inside diameters) → 0.20 in² of cable; ¾ in. allows 0.21 in² at 40 %, so it is the minimum size (sx-tg016-2020; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Fan Laws, Grille Sizing, and Hydronic Flow Calculator — Affinity Laws, Face Velocity, GPM from ΔT

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/fieldextras.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The fan laws, grille sizing, and hydronic GPM — the HVAC arithmetic that comes up on the electrical side. Formulas only; the equipment selection tables and the mechanical engineer govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • FAN-01 — 1,000 → 2,000 rpm; 10,000 CFM; 1.5 in SP; 10 BHP → 20,000 CFM; 6 in SP; 80 BHP (eval-2026-09-07; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Trench Excavation Calculator — OSHA Sloping, Cut, Spoil, Trucks, Bedding, Backfill

Standard and edition
OSHA 29 CFR 1926 (construction) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/fieldextras.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Trench volumes with the OSHA slope built in — cut, spoil, trucks, bedding, backfill. Appendix B slopes and the Subpart P requirements the competent person enforces; the geotech and the engineer of record govern deep or unusual cuts. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • TRENCH-01 — Stable rock, Type A, Type A short-term, Type B, Type C → Vertical 90°; 3/4:1 53°; 1/2:1 63° (12 ft or less); 1:1 45°; 1½:1 34° (osha-1926-p-appb; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Busway Load and Voltage Drop Calculator — Plug-In Taps, Manufacturer Impedance, NEC 368

Standard and edition
NFPA 70, National Electrical Code 2023 — These calculations follow the 2023 edition. The 2026 edition is published and moved or changed some sections; the edition your AHJ has adopted governs — check it before you rely on a section number or a value.
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The loading and voltage drop along a plug-in busway run, tap by tap. Physics on the manufacturer's impedance; Article 368 notes. Typical approach for field use; a licensed engineer confirms design values. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BUS-01 — ReliaGear copper 225 A: R 5.1, X 3.75 mΩ per 100 ft; 225 A at 100 ft, three-phase → Line-to-line drop per 100 ft at PF 0.3 to 1.0: 1.99, 2.13, 2.26, 2.36, 2.43, 2.47, 2.43, 1.99 V (abb-reliagear-2022; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Battery Bank Calculator — Ah from Loads, Days of Autonomy, DoD, Series / Parallel, Recharge Time

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The battery bank for a load, days of autonomy, and a charger. Formulas only; the battery's data sheet governs its charge rate and cycle life. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • BATT-01 — 7,463 Wh/day at 24 V, 7 days of autonomy, 80 % depth of discharge, 12 V 478 Ah batteries → 2,721 Ah; 2 in series × 6 in parallel = 12 batteries; 2,868 Ah; 68.8 kWh (la-dnr-standalone-pv; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Rack-U Planner — Space, Weight, Power, and PDU Outlets with A/B Redundancy

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Does it fit the rack — U, weight, power, and outlets, with A/B redundancy done right. Arithmetic on the nameplates; the PDU's and rack's ratings are the record. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Electrical Formula Sheet — Ohm's Law, AC Power, Voltage Drop, Motors, Transformers, Reactance, Conversions

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/formulas.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The formula sheet — Ohm's law through transformers, on one card. Reference only. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
None yet — covered by the author-written harness only (self-consistency, not independent confirmation).
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Earthwork Calculator — Grid Cut and Fill, Stockpile Volume, Aggregate Tonnage, Grade and Slope

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Dirt arithmetic — cut and fill, piles, tonnage, and grade. Geometry with the densities and factors you enter; the survey and the supplier's yield sheet govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • EW-01 — 100 yd³ of bank cut at 30 % swell → 130 yd³ loose (sulaimani-excavation; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Glycol Fill Calculator — System Volume from Pipe Segments and Equipment, Glycol and Water Gallons, Freeze Point

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js, engine/plumbing.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
How much glycol the loop takes — pipe by pipe, plus the gear. Pipe IDs from the plumbing engine (ASME B36.10 / B88); freeze points are the commonly published approximations, and the supplier's chart is the record. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • GLY-01 — Ethylene glycol at 20, 25, 30, 40 and 50 % by volume → 16, 10, 4, −12 and −34 °F (within 0.5 °F) (dowtherm-sr1; engine)
  • GLY-02 — Propylene glycol at 44.7 % by volume → −16.1 °F (within 0.5 °F) (dowfrost-spec; engine)
  • GLY-03 — Water per foot of Schedule 40 ½ and 1 in and copper type L ½ and 1 in → 0.0158, 0.0449, 0.0121 and 0.0429 gal (within 0.0001) (etb-water-content; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Psychrometric Calculator — Dew Point, Wet Bulb, Humidity Ratio, Enthalpy, Coil Load

Standard and edition
ASHRAE Handbook — Fundamentals psychrometrics 2021
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The psychrometric chart, solved. ASHRAE Fundamentals formulas at the site's altitude; the mechanical engineer's load calculation governs. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • PSY-01 — Saturated air at 35 °F and 14.7 psia, heated to 100 °F → W 0.004259; h 12.985 Btu/lb; after heating h 28.708 Btu/lb (iac-appendix-b; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Scaffold Load Calculator — OSHA 1926.451 Duty Ratings, Plank Spans, Leg Loads at 4:1, Tie-Off Height

Standard and edition
OSHA 29 CFR 1926 (construction) current CFR — Federal text; State Plan states may be stricter.
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Scaffold loading with the OSHA numbers built in — duty, plank span, leg load at 4:1, the tie-off height. 1926.451 and Appendix A (public); the frame manufacturer's capacity and the competent person are the record. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • SCAF-01 — 2 × 10 in. solid sawn planks at 25, 50 and 75 psf; full-thickness and nominal lumber; the duty ratings and the one-person load → Spans 10, 8 and 6 ft (full thickness) and 8 and 6 ft (nominal; none at 75 psf); light 25, medium 50, heavy 75 psf; one person 250 lb (osha-1926-l-appa; engine)
  • SCAF-02 — Capacity factor; a 20 ft scaffold on a 5 ft base, and 20.01 ft → 4 × the maximum intended load; more than 4:1 must be restrained from tipping (exactly 4:1 is not) (cfr-1926-451; engine)
  • SCAF-03 — A leg carrying 300 lb of the scaffold's own weight and 875 lb of intended load → 3,800 lb: its own weight plus 4 × the load (1926.451(a)(1)) (cfr-1926-451; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Crane Wind Load Calculator — Sail Area, Wind Force, Percent of Chart, Stop-Work Wind

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The wind on the load, against the chart — before the lift, not during it. Physics on the operator's chart numbers; the manufacturer's wind limits and the lift plan govern. Extends the Rigging tool. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • CRANE-01 — 65 t hoist load, 280 m² of wind area (projected area × cD), the chart's permissible wind 11.2 m/s (metric in, exact conversions) → Over EN 13000's 1.2 m²/t (78 m²): the permissible wind is lowered to 5.9 m/s (liebherr-2024-wind; engine)
  • CRANE-02 — 85 t hoist load, 60 m² of wind area, the chart's permissible wind 9 m/s → Under the 102 m² reference: the chart's 9 m/s stands (liebherr-2024-wind; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Hydrant Flow Test Calculator — NFPA 291 Pitot Flow and Supply Curve at 20 psi

Standard and edition
NFPA 291, Fire Flow Testing and Marking of Hydrants 2022 — Nozzle coefficient and test quality are yours to judge.
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
The hydrant flow test, reduced to the supply curve. NFPA 291 formulas; the water purveyor's and the fire protection engineer's records govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • HYD-01 — Static 98 psi, residual 86 psi, pitot 23 psi, one 2½ in. outlet, c 0.90 → 804 gpm flowing; 2,209 gpm available at 20 psi residual (temecula-fireflow; engine)
  • HYD-02 — Static 80 psi with residuals of 72 and 72.01 psi (a 10 % drop, and just under) → Under 10 % flagged as too small a drop to build the curve; exactly 10 % accepted (meyerfire-2024-nfpa291; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Hip and Valley Rafter Calculator — Lengths per Foot of Run, Jack Rafter Differences, Floor Joist Takeoff

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js, engine/dimensions.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Hips, valleys, jacks, and joists — the framing square, in the browser. Geometry; lumber sizes and spans come from the tables and the engineer. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • HIP-01 — 10 ft run at 9 in 12, no overhang; jacks at 16, 18, 20 and 24 in centers → Common 12 ft 6 in; hip 16 ft ⅛ in; jack differences 20, 22½, 25 and 30 in (within ¹⁄₁₆ in) (dewalt-dwht46031; engine)
  • HIP-02 — A 24 in common-rafter eave at 9 in 12 → Hip eave 24 × 1.28 = 30.72 in (dewalt-dwht46031; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Metal Deck and Grating Takeoff and Weld Consumable Calculator — Sheets, Weight, Electrode Pounds

Standard and edition
No published table is transcribed — arithmetic, geometry, or a reference the page names inline
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Deck sheets and weld wire — two ironwork takeoffs. Geometry and the standard deposition efficiencies; the deck schedule and the WPS govern. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • WELD-01 — Stick (E7018) fillet welds of 1/4 in and 5/16 in, no waste → 0.22 and 0.33 lb of electrode per ft; the engine at or up to 6 % above (production data) (aisc-msc-1997-welding; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.

Masonry Veneer Tie, Flashing, and Weep Calculator — TMS 402-22 Spacings

Standard and edition
TMS 402 masonry veneer anchorage 2022 (referenced by the 2024 IBC) — Maximum spacings for takeoff, not a structural design.
Engine
engine/lhf.js · build 2026.10.13 · last change 2026-10-09
Scope and exclusions
Veneer ties, flashing, and weeps — counted from the wall. TMS 402-22 prescriptive maximums (public); the wall section governs. Extends Brick & Block Takeoff. No number you enter leaves your browser — we count calculations by type only.
External known-answer cases pinned in the harness
  • TIE-01 — Anchored veneer, prescriptive basic tie spacing (TMS 402-22) → At most 2.67 ft² of wall per tie (prescriptive basic) (bia-tn3c-2026; engine)
  • TIE-02 — Anchored veneer, Prescriptive Enhanced (TMS 402-22) → At most 1.78 ft² of wall per tie and 16 in. maximum spacing (bia-tn3c-2026; engine)
Review
Author-reviewed and harness-tested. Independent reviewer: not yet assigned. Until one is, treat the result as a typical approach that a licensed engineer confirms.