If a generator supplies standby power for a separate building, when is a separate disconnecting means not required?

The correct answer is that no separate disconnecting means is required when both conditions are satisfied: the generator is listed for the purpose of supplying standby power and it is located outside.

When a generator is specifically listed for use as a standby power source, it complies with safety and technical standards that ensure it can operate safely without necessitating additional disconnects. This listing serves as a recognition by authorities having jurisdiction that the equipment is suitable for its intended application, thus reducing the need for additional safety measures like a separate disconnect.

Moreover, if the generator is situated outside, it typically does not pose the same risks associated with indoor installations, such as potential fire hazards or accessibility for maintenance. Outdoor generators are often designed with features that accommodate their external environment, further mitigating risks and demonstrating that safety has already been considered and addressed in the product design.

Therefore, the combination of being both listed for such use and located outside confirms that a separate disconnecting means is unnecessary in this context, aligning with safety regulations and best practices.