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 CATALOGCalculator results
SCCR / AIC Fault Current Compliance Checker
Distinguish AIC (device interrupting capacity) from SCCR (assembly withstand rating) and explain why both must be checked.
- NEC
- SCCR
- AIC
Box Fill Calculator
Apply the five NEC 314.16(B) counting categories — conductors, clamps, support fittings, device yokes, and equipment grounding conductors — and sta…
- NEC
- BOX FILL
- NEC 314.16
Commercial Load Build-Up Calculator
Apply the correct NEC Article 220 demand factor for each commercial load category — general lighting (220.42), non-dwelling receptacles (220.14(H))…
- NEC
- COMMERCIAL LOAD
- SERVICE LOAD
Conductor Ampacity & Wire Sizing Calculator
Look up conductor ampacity from NEC Table 310.16 on the 90°C column, then cap the result at the terminal temperature rating under 110.14(C).
- NEC
- AMPACITY
- CONDUCTOR SIZING
Conductor Derating & Adjustment Explorer
Apply temperature correction factor from NEC 310.15(B)(2) for the actual ambient temperature and explain why a higher ambient reduces allowable amp…
- NEC
- CONDUCTOR DERATING
- ADJUSTMENT FACTOR
Conduit Fill Calculator
Apply the NEC Chapter 9, Table 1 fill percentage limits — 53% for one conductor, 31% for two, 40% for three or more — to a raceway fill calculation.
- NEC
- CONDUIT FILL
- NEC CHAPTER 9
Continuous Load Sizing Basis Calculator
State the NEC definition of a continuous load (maximum current for 3 hours or more) and explain why the classification triggers the 125% sizing mul…
- NEC
- CONTINUOUS LOAD
- NONCONTINUOUS LOAD
Dwelling Unit Load Calculator
Apply the NEC Standard Method under Article 220 Part III to a single-family dwelling, calculating general lighting load, small appliance branch cir…
- NEC
- DWELLING UNIT
- RESIDENTIAL LOAD
General Lighting & Receptacle Branch-Circuit Calculator
Look up the general lighting VA/ft² value from NEC Table 220.12 for a given occupancy type and calculate the total general lighting load for a defi…
- NEC
- GENERAL LIGHTING
- RECEPTACLE
Grounding Electrode Conductor (GEC) Sizing Calculator
Look up the GEC size from NEC Table 250.66 given the largest service-entrance or feeder conductor size and explain why the GEC is sized from the so…
- NEC
- GEC
- NEC 250.66
Equipment Grounding Conductor (EGC) Sizing Calculator
Look up the minimum EGC size from NEC Table 250.122 given a known OCPD rating and explain why EGC sizing is based on OCPD rather than load current.
- NEC
- EGC
- NEC 250.122
HVAC & Refrigeration MCA / MOCP Interpreter
Explain the difference between Article 440 (nameplate-driven) and Article 430 (calculation-driven) sizing and identify which applies to hermetic re…
- NEC
- HVAC
- MCA
Motor Branch-Circuit Conductor & OCPD Study Tool
Look up full-load current from NEC Tables 430.248 and 430.250 for single-phase, three-phase, and synchronous motors, and explain why nameplate amps…
- NEC
- MOTOR BRANCH CIRCUIT
- NEC ARTICLE 430
Multiple Motor Feeder & Service Calculator
Apply NEC 430.24 to size a feeder conductor for multiple motors — 125% of the largest motor FLC plus 100% of every other motor FLC plus any non-mot…
- NEC
- MOTOR FEEDER
- NEC 430.24
OCPD Sizing Calculator
Apply the NEC 240.4(B) next-standard-size-up rule and identify when it is permitted versus when 240.4(D) imposes a hard cap based on conductor size.
- NEC
- OCPD
- OVERCURRENT PROTECTION
Panelboard & Feeder Load Calculation
Identify which NEC Article 220 demand factor applies to each load category — general lighting (220.42), non-dwelling receptacles (220.14(H)), offic…
- NEC
- PANELBOARD LOAD
- FEEDER LOAD
Service & Feeder Conductor Sizing Calculator
Apply the NEC continuous-load multiplier (125%) to calculate minimum conductor ampacity for feeders and services under Articles 215 and 230.
- NEC
- SERVICE ENTRANCE
- FEEDER CONDUCTOR
Voltage Drop Calculator & Explorer
Calculate AC voltage drop percentage using conductor resistance and reactance from NEC Chapter 9 tables, applying power factor and temperature corr…
- NEC
- IEEE
- VOLTAGE DROP
EV Charger Branch, Feeder & Service Calculator
Apply the NEC Article 625 continuous-load factor to EVSE branch circuit sizing.
- NEC
- EV CHARGER
- EVSE