What must be marked on PV source circuits according to Article 690?

The marking requirements for photovoltaic (PV) source circuits as outlined in Article 690 of the National Electrical Code (NEC) are crucial for ensuring safety and proper operation. A warning sign indicating the presence of ungrounded conductors is essential because PV systems often have conductors that remain energized, even in the absence of sunlight. This can pose a significant shock hazard to anyone working on or near the system. Therefore, the code mandates that these circuits must clearly indicate this risk to protect installers, maintenance personnel, and emergency responders by alerting them to the potential dangers associated with ungrounded PV conductors.

Marking the voltage rating, manufacturer details, or type of inverter used, while informative, does not specifically address the immediate safety risks associated with ungrounded conductors. The primary goal of the warning sign is to enhance awareness and ensure that individuals understand they are working with live circuits that could lead to electrical hazards.