CSLB C-46 Solar ContractorElectrical and Plumbing CodesHard
A solar contractor is designing a PV system for a single-family dwelling that will include a rapid shutdown system. According to NEC Article 690.12, what is the maximum permissible time for the controlled conductors outside the array to be reduced to no more than 30 volts and 240 volt-amperes after initiation of the rapid shutdown function?
- A10 seconds
- B5 seconds
- C30 seconds
- D60 seconds
Show answer & explanationAnswer & explanation
Correct answer: C. 30 seconds
NEC Article 690.12, which covers rapid shutdown of PV systems, mandates that the controlled conductors outside the array boundary must be reduced to no more than 30 volts and 240 volt-amperes within 30 seconds of initiating the rapid shutdown function. This critical safety measure ensures that emergency responders can safely operate around the PV system.
Why the other options are wrong
- A. 10 seconds is too short and not the specified time in the NEC.
- B. 5 seconds is too short and not the specified time in the NEC.
- D. 60 seconds is too long and does not meet the rapid shutdown requirements.
NEC Rapid Shutdown Time
The maximum time allowed by NEC 690.12 for controlled conductors outside the PV array boundary to be de-energized to safe voltage and power levels after rapid shutdown initiation.
- Mandated by NEC 690.12.
- 30 seconds maximum time.
- Target: ≤30V and ≤240VA outside array boundary.
Memory trick: Rapid shutdown's time is thirty, so first responders stay safe and dirty!