⚡ Circuit Parameters
FAQ
How do I choose the right breaker size?
The breaker rating must be ≥ the calculated load current. Continuous loads (running ≥3 hours) require a 125% multiplier per NEC. Motor loads need consideration of inrush current (typically 250%). Standard breaker sizes: 15, 20, 25, 30, 35, 40, 45, 50, 60A, etc.
Why distinguish continuous vs non-continuous loads?
Per NEC, continuous loads (operating 3+ hours daily — lighting, HVAC, electric ranges) require breaker rating ≥ 125% of load current to prevent nuisance tripping from sustained heat buildup.
Why do motor loads need larger breakers?
Motors draw 6-8× rated current at startup (inrush), but only for milliseconds. NEC allows motor breakers up to 250% of FLA, with thermal overload relays providing continuous protection.
How do I select the right wire size?
Wire ampacity must be ≥ breaker rating. Standard copper wire: 14AWG=15A, 12AWG=20A, 10AWG=30A, 8AWG=40A, 6AWG=55A. This calculator auto-recommends the correct gauge.