At what dc voltage or greater must photovoltaic systems be protected by a listed PV arc-fault circuit interrupter?

Photovoltaic systems must be protected by a listed PV arc-fault circuit interrupter when the system operates at a direct current (DC) voltage of 80 volts or greater. This requirement is in place to safeguard against potential hazards associated with arcs that can occur in the circuit due to insulation failures, connections, or damage to the wiring.

The selection of 80 volts is significant because it represents a threshold where the risks of electrical arcing increase, thus necessitating additional protective measures to enhance safety. The design of the arc-fault circuit interrupter is specifically tailored to detect these dangerous conditions and disconnect the circuit before a fire or other hazardous event can occur.

Protection below this voltage is not mandated because the likelihood and consequences of arcing are considerably lower, and traditional circuit protection methods are generally sufficient for those lower voltages. Thus, the requirement to employ arc-fault protection aligns with safety standards aimed at preventing electrical fires and ensuring the reliable operation of photovoltaic systems.