Under GFPE rules for feeder disconnects, when is a 1,000-amp feeder disconnect not required to have GFPE?

Under GFPE rules for feeder disconnects, when is a 1,000-amp feeder disconnect not required to have GFPE?

• A. If GFPE is on the supply side of the feeder disconnect (such as on the service disconnect)
• B. If the system is delta-connected
• C. If the feeder disconnect is installed indoors
• D. If the load is less than 500 A

Answer: (A)

The key idea is that protection for ground faults can be provided from the source, not just at the downstream device. If a Ground-Fault Protection for Equipment (GFPE) device is located on the line side of the feeder disconnect—for example at the service disconnect—it monitors and interrupts any ground faults on the feeder and everything downstream. Since that upstream GFPE already protects the entire feeder circuit, there’s no need to add a separate GFPE on the feeder disconnect itself. The upstream protection fulfills the requirement for rapid fault clearing for that feeder and its downstream equipment. The other factors—being delta-connected, the feeder being indoors, or the load being under a certain size—don’t by themselves remove the GFPE requirement. They may influence other design considerations, but they don’t negate the protection provided by an upstream GFPE.

The key idea is that protection for ground faults can be provided from the source, not just at the downstream device. If a Ground-Fault Protection for Equipment (GFPE) device is located on the line side of the feeder disconnect—for example at the service disconnect—it monitors and interrupts any ground faults on the feeder and everything downstream. Since that upstream GFPE already protects the entire feeder circuit, there’s no need to add a separate GFPE on the feeder disconnect itself. The upstream protection fulfills the requirement for rapid fault clearing for that feeder and its downstream equipment.

The other factors—being delta-connected, the feeder being indoors, or the load being under a certain size—don’t by themselves remove the GFPE requirement. They may influence other design considerations, but they don’t negate the protection provided by an upstream GFPE.