Motors, Transformers & Protection
Motor branch-circuit conductors, breakers and overloads, transformer sizing with primary and secondary OCPD, overcurrent device selection, available fault current and AIC verification, arc flash incident energy and power triangle fundamentals.
Motor Branch Circuit Calculator
Size conductors, OCPD, thermal overload protection, and disconnect switch for AC electric motors per NEC Article 430 and Tables 430.248 & 430.250.
Open calculator NEC 2026 / 2023Transformer Sizing & OCPD Calculator
Size low-voltage dry-type and liquid transformers (kVA), calculate primary/secondary Full-Load Amps (FLA), size 125% OCPD per NEC §450.3(B), and estimate secondary fault current.
Open calculator NEC 2026 / 2023Overcurrent Protection Selector
Select the standard circuit breaker or fuse size per NEC §240.6(A). Applies the 125% continuous load factor, conductor ampacity protection, and §240.4(B) next-size-up rule.
Open calculator NEC 2026 / 2023Fault Current / AIC Calculator
Calculate available short-circuit fault current (AFC) and Ampere Interrupting Capacity (AIC) at service panels using the point-to-point method per NEC §110.24 and §110.9.
Open calculator NEC 2026 / 2023Arc Flash Incident Energy Calculator
Estimate arc flash incident energy (cal/cm²), flash boundary distance, NFPA 70E PPE Category, and NEC §110.16 safety label requirements.
Open calculator NEC 2026 / 2023Electrical Fundamentals & Power Triangle Calculator
Calculate Ohm’s Law (V, I, R, P), 3-phase AC power triangle (kW, kVA, kVAR, PF), horsepower to kW/Amps, and kVA↔Amps conversions.
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