Physics & Engineering / Electrical Engineering
Circuit Breaker Size Calculator
Loads operating for 3 hours or more
Loads operating for less than 3 hours
NEC Requirements
Continuous loads: Multiply by 125% (1.25) safety factor
Non-continuous loads: Use actual load (100%)
Mixed loads: (Continuous × 1.25) + Non-continuous
Examples of continuous loads: Lighting, HVAC, motors running >3 hours
Note: Always consult NEC and licensed electrician for installation. This is for estimation only.
See Also
Other calculators in Electrical Engineering