CSLB C-46 Solar ContractorElectrical and Plumbing CodesEasy
A solar contractor is planning the DC wiring for a new ground-mounted PV array. The array will consist of multiple strings, each operating at 400 VDC. The contractor needs to ensure that the overcurrent protection device (OCPD) for each string is appropriately sized. According to the National Electrical Code (NEC), what is the minimum continuous current rating for the OCPD protecting the PV array conductors?
- A100% of the maximum circuit current
- B125% of the maximum circuit current
- C150% of the maximum circuit current
- D80% of the maximum circuit current
Show answer & explanationAnswer & explanation
Correct answer: B. 125% of the maximum circuit current
NEC Article 690.8(B) requires that the maximum circuit current for PV array conductors be multiplied by 125% to determine the minimum continuous current rating for the overcurrent protection device. This accounts for continuous operation and potential variations.
Why the other options are wrong
- A. 100% does not account for continuous operation as required by NEC.
- C. 150% is not the standard multiplier for this specific application in the NEC.
- D. 80% is incorrect and would lead to undersized protection.
PV OCPD Sizing
Overcurrent protection devices for PV array conductors must be sized at 125% of the maximum circuit current to account for continuous operation.
- NEC 690.8(B) applies.
- Ensures device can handle sustained loads.
- Prevents nuisance tripping and ensures safety.
Memory trick: PV OverCurrent Protection: Always Boost by a Quarter.