Western Electrical Contractors Association (WECA) 103 Practice Test

Which rule describes the overcurrent protective device sizing for continuous loads on a 1200 W space heater?

120% rule 100% rule 125% rule 150% rule

Correct Answer:

125% rule

Explanation:

Continuous loads, like a space heater that can run for long periods, require the overcurrent protective device to be sized at 125% of the continuous load. This extra margin accounts for heat buildup and ensures the circuit won’t nuisance-trip while still protecting the conductors. For a 1200 W heater on a 120 V circuit, the current is 10 A. Multiplying by 1.25 gives 12.5 A, so you’d choose the next standard size up, typically a 15 A breaker. That’s why the 125% rule is the correct approach here. The 100% rule would not provide enough allowance for continuous operation, and the 120% or 150% options do not align with NEC practice for continuous loads.

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