Electrical calculators
19 calculators across branch circuits, feeders, services, motors, conduit fill, and voltage drop. All browser-based, all show their work.
VIEW IN LAB CATALOGSCCR / AIC Fault Current Compliance Checker
Check assembly SCCR and device AIC ratings against available fault current — with a sensitivity analysis, equipment comparison explorer, step-by-step calculation trace, current-limiting fuse impact, and NEC code-logic walkthrough.
Box Fill Calculator
Calculate NEC 314.16 box fill volume by entering conductors, looped conductors, internal cable clamps, device yokes, and equipment grounding conductors — with a box cross-section visualization, category breakdown, five preset scenarios, and a knowledge-check quiz.
Commercial Load Build-Up Calculator
Build a commercial service load from the ground up across 13 occupancy types — stacking general lighting, receptacle, motor, HVAC, sign, and special loads with NEC Article 220 demand factors applied per category, with a load stack chart, what-if scenarios, load balance analysis, and calculation trace.
Conductor Ampacity & Wire Sizing Calculator
Size conductors under NEC Article 310 — pick load, material, insulation, and terminal rating, then apply ambient temperature correction and bundling adjustment factors in the correct code order to land on a compliant AWG/kcmil size.
Conductor Derating & Adjustment Explorer
Apply temperature correction and bundling adjustment factors to conductor ampacity in the correct NEC order — with table selection (310.16 vs. 310.17), neutral CCC determination, terminal temperature cap, and parametric charts showing how each factor shifts the final allowable ampacity.
Conduit Fill Calculator
Add conductors by wire type, AWG, and insulation to any of seven raceway types — get live NEC Chapter 9 fill percentage, pass/fail status, and auto-select the smallest compliant conduit size, with a step-by-step trace and design challenge mode.
Continuous Load Sizing Basis Calculator
Enter continuous and noncontinuous load amperes for a branch circuit, feeder, or service and get the NEC sizing basis — with the 125% multiplier applied correctly, the 100%-rated assembly exception explained as a listing condition, and edition-specific notes for 2017, 2020, and 2026.
Dwelling Unit Load Calculator
Calculate dwelling service load using all three NEC Article 220 methods — Standard (220.82 Part III), Optional (220.82), and Existing Dwelling (220.83) — with side-by-side comparison, service size ladder, and five preset scenarios including an undersized service case.
General Lighting & Receptacle Branch-Circuit Calculator
Size general lighting and receptacle branch circuits under NEC Articles 210 and 220 — with occupancy VA/ft² lookup, custom VA entry, continuous-load factor, receptacle and dedicated-load configuration, and a circuit designer with self-test mode.
Grounding Electrode Conductor (GEC) Sizing Calculator
Size the grounding electrode conductor from NEC Table 250.66 for service entrances and separately derived systems — with electrode-type sub-rules (250.66(A/B/C)), parallel conductor sets, material selection, and six preset configurations.
Equipment Grounding Conductor (EGC) Sizing Calculator
Size equipment grounding conductors from NEC Table 250.122 — with upsizing for derated phase conductors, parallel feeder configurations, raceway-as-EGC path evaluation, and a visual EGC vs. GEC distinction diagram.
HVAC & Refrigeration MCA / MOCP Interpreter
Read HVAC and refrigeration equipment nameplates correctly under NEC Article 440 — enter marked MCA and MOCP values, select your conductor and OCPD, and get an immediate pass/fail against both nameplate requirements with a live circuit visualizer and a side-by-side Article 440 vs. 430 comparison.
Motor Branch-Circuit Conductor & OCPD Study Tool
Size branch-circuit conductors, overload protection, and OCPD for single-motor circuits under NEC Article 430 — with a live one-line diagram, motor starting current simulation, illustrative TCC, Table 430.52(C)(1) multiplier matrix, copper-vs-aluminum comparison, and self-test mode.
Multiple Motor Feeder & Service Calculator
Add multiple motors and optional non-motor loads to size a feeder conductor and feeder OCPD under NEC Article 430 — two distinct calculations (430.24 and 430.62) with FLC table lookups, a step-by-step trace, and six common-mistake guards built in.
OCPD Sizing Calculator
Size overcurrent protective devices for general, continuous, and motor branch circuits under NEC 240.4 and 430.52 — with device-type selector, next-standard-size logic, conductor protection check, 100%-rated assembly exception, and seven preset scenarios illustrating common sizing traps.
Panelboard & Feeder Load Calculation
Build a multi-category panelboard or feeder load schedule with NEC Article 220 demand factors applied per category — general lighting, receptacles, kitchen, motors, HVAC, and more — then evaluate feeder conductor sizing and bus utilization.
Service & Feeder Conductor Sizing Calculator
Size service entrance and feeder conductors under NEC Articles 215 and 230 — with continuous-load factor, ambient and bundling correction, material and terminal temperature cap, voltage drop, and a design challenge mode.
Voltage Drop Calculator & Explorer
Calculate AC voltage drop for single- and three-phase circuits across five voltages and two conductor materials — with live parametric charts (drop vs. length, vs. current, vs. temperature), a copper-vs-aluminum comparison, conductor explorer, six quick presets, and a scenario lab.
EV Charger Branch, Feeder & Service Calculator
Size branch circuits, feeders, and service entrances for EVSE installations under NEC 625 — supporting Level 1, Level 2, and DC Fast charging with demand factor application and multi-unit feeder aggregation.