A generator is considered Separately Derived System when the Automatic Transfer Switch breaks the neutral conductor.

• A. True
• B. False
• C. Sometimes
• D. Not specified

Answer: (A)

Separately derived systems are created when a power source other than the utility supplies the load and the neutral is isolated from the building’s grounding system. If the Automatic Transfer Switch opens the neutral conductor, the generator’s neutral is no longer tied to the building’s neutral and grounding path. This isolation means the generator provides its own neutral reference and bonding point, effectively forming a separate source with its own grounding arrangement. That aligns with being a separately derived system.

If the neutral stayed connected, the system would still share the building’s grounding reference, so it wouldn’t be considered separately derived. The key is the neutral being broken, which stops any shared neutral-ground bond through the service and makes the generator-side system independent.