#nec

Cable-tray fill engineering maths as an API, computed locally and deterministically from NEC Article 392 — the allowable-fill, single-layer and tray-width numbers an electrician, estimator or designer runs for a tray run. The fill endpoint applies NEC 392.22(A)(1) Column 1 for multiconductor power and lighting cables no larger than 4/0 in a ladder or ventilated-bottom tray: the total cable cross-sectional area is capped at the tray width × 7/6, so a 12-inch tray allows 14 in² — sum every cable's csa, get the percentage fill and whether it is within code, with the spare area left. The large-cable endpoint covers cables 4/0 and larger, which must lie in a single layer with the sum of their diameters not exceeding the tray width — no stacking — so it returns the spare width and the code check. The min-width endpoint inverts the rule to size the tray: minimum width = cable area × 6/7, rounded up to a standard 6/9/12/18/24/30/36-inch width, leaving room for spare capacity and future cables. Everything is computed locally and deterministically, so it is instant and private. Ideal for electrical-design and estimating tools, industrial and OSP utilities, and code-check calculators. Pure local computation — no key, no third-party service, instant. Ladder/ventilated trays; solid-bottom and mixed fills use the other NEC columns, and ampacity must be derated for fill. 3 compute endpoints. For conduit and box fill use a conduit API.

api.oanor.com/cabletray-api

Electric-motor electrical maths as an API, computed locally and deterministically — the full-load-current, NEC-sizing and starting-current numbers an electrician, panel designer or estimator runs for every motor circuit. The full-load-amps endpoint gives the motor current from its power, voltage and phase: FLA = (output ÷ efficiency) ÷ (√3 × volts × power factor) for three-phase (drop the √3 for single-phase) — a 10 hp, 460 V, three-phase motor at 90 % efficiency and 0.85 power factor draws about 12.2 A — and it also returns the input kW and kVA. The sizing endpoint applies NEC Article 430 from the full-load current: branch-circuit conductors at 125 %, overload protection at 115–125 % by service factor, and branch-circuit short-circuit/ground-fault protection up to 250 % for an inverse-time breaker or 175 % for a time-delay fuse — the larger protection lets the inrush pass while the overload guards the windings. The starting endpoint gives the locked-rotor (inrush) current, about six times full-load for an across-the-line start, the figure that sets the voltage dip and why soft starters and VFDs exist. Everything is computed locally and deterministically, so it is instant and private. Ideal for electrical-design and estimating tools, panel-builder and field utilities, and engineering calculators. Pure local computation — no key, no third-party service, instant. Calculated values — use the NEC FLC tables for code work. 3 compute endpoints. For general three-phase power use a three-phase API; for conduit fill a conduit API.

api.oanor.com/motorfla-api

NEC conduit-fill and box-fill maths as an API, computed locally and deterministically — the electrical-code calculations an electrician or estimator does on every run. The conduit-fill endpoint takes a set of conductors (as size:count pairs, e.g. 12:3,10:2) and a conduit trade size and returns the conductor cross-sectional area, the conduit's internal area, the fill percentage and whether it stays within the NEC Chapter 9 limit — 53 % for a single conductor, 31 % for two, 40 % for three or more — so nine #12 THHN fill a half-inch EMT to 39 % (legal) but ten do not. The box-fill endpoint applies NEC 314.16(B): each conductor adds its free-space allowance (2.00 in³ for #14, 2.25 for #12, and so on), a device yoke counts as two, internal cable clamps as one, and all equipment grounds together as one — all at the largest conductor's volume — to give the minimum junction-box size, checked against a box volume if you give one. Uses the THHN/THWN and EMT areas from NEC Chapter 9. Everything is computed locally and deterministically, so it is instant and private. Ideal for electrical-contractor, estimating, inspection and electrician app developers, conduit and box-sizing tools, and apprentice training. Pure local computation — no key, no third-party service, instant. Imperial: square inches and cubic inches. Live, nothing stored. 2 compute endpoints. Always verify against the adopted code edition — this is an estimating aid, not an inspection.

api.oanor.com/conduit-api