Applying new 480v GFCI standard in an industrial facility

Although Class A Ground-Fault Circuit Interrupters (GFCIs) have been responsible for a substantial reduction in residential electrocutions, their limitation on system voltage (maximum 240 V) and their maximum allowable leakage current of 6 mA make them impractical for 480 or 600 V industrial power systems. UL 943C defines special-purpose GFCIs that can be used on systems up to 600 V and allow for a leakage current of 20 mA. For higher leakage currents up to 50 mA, Equipment Ground-Fault Protection Devices (EGFPDs) can be used. Also required by UL 943C is the ability to monitor the ground wire continuity and interrupt power to the load if ground integrity is lost. In this paper the differences between GFCIs and EGFPDs as well as field applications are discussed. The field application involves design selection criteria, field installation considerations, and use of ground-fault circuit interrupters or equipment ground-fault protection devices for preventative maintenance as well as preventing shock hazards.