CSLB C-10 Electrical ContractorEquipment and InstallationMedium
A dedicated lighting branch circuit supplies a continuous load of 32 amperes for 4+ hours daily. What is the minimum standard overcurrent device size required for this branch circuit conductor?
- A45 amperes
- B40 amperes
- C32 amperes
- D35 amperes
Show answer & explanationAnswer & explanation
Correct answer: B. 40 amperes
Continuous loads require conductors and OCPDs sized at 125% of the continuous load per NEC 210.19(A) and 210.20(A). 32A × 1.25 = 40A, which is a standard breaker size, so a 40A OCPD is the minimum.
Why the other options are wrong
- A. 45A exceeds the calculated minimum and is not a standard breaker size, making it an unnecessary oversizing.
- C. 32A equals only 100% of the load; continuous loads require the 125% multiplier.
- D. 35A is not a standard overcurrent device size and is below the calculated 40A minimum.
Continuous Load Sizing
Continuous loads (operating 3+ hours) require branch-circuit conductors and OCPDs rated at not less than 125% of the continuous load per NEC 210.19/210.20.
- Continuous = operates 3 hours or more
- Formula: OCPD/conductor ≥ 1.25 × continuous load
- Round up to next standard OCPD size if calculated value isn't standard
Memory trick: Continuous loads need a 25% safety cushion.