CSLB C-46 Solar ContractorElectrical and Plumbing CodesHard
A solar contractor is installing a grid-tied PV system on a commercial building. The inverter for the system has a maximum continuous output current of 50 amperes. The feeder circuit supplying the PV system disconnect is protected by a 100-ampere overcurrent protective device. According to the National Electrical Code (NEC), what is the maximum allowable continuous current for the PV system's AC output circuit conductors before applying any adjustment or correction factors?
- A125 amperes
- B50 amperes
- C40 amperes
- D62.5 amperes
Show answer & explanationAnswer & explanation
Correct answer: D. 62.5 amperes
The NEC requires that the continuous current for AC output circuits of PV systems be calculated at 125% of the maximum continuous current rating of the inverter (or sum of inverters). Therefore, 50 amperes * 1.25 = 62.5 amperes.
Why the other options are wrong
- A. 125 amperes is 125% of the OCPD, not the inverter output, and is not the continuous current for the conductors.
- B. 50 amperes is the inverter's maximum continuous output current, but the NEC requires multiplying this by 125% for the circuit conductors.
- C. 40 amperes is 80% of the inverter's output, which is not the correct calculation for continuous current.
NEC PV AC Output Circuit Continuous Current
The National Electrical Code (NEC) requirement to calculate the continuous current for PV AC output circuit conductors at 125% of the inverter's maximum continuous output current rating to account for continuous operation.
- Applies to AC output conductors from PV inverters.
- Uses a 125% multiplier for continuous current.
- Ensures conductors are adequately sized for sustained operation.
Memory trick: Solar AC needs 125% more respect for continuous flow.