Reducing Electrocutions in Industry: Application of a Class C Ground-Fault Current Interrupter in a Pulp and Paper Plant

Historically, Class A Ground-fault circuit interrupters (GFCIs) have been responsible for a substantial reduction in residential electrocutions. Yet they have not had much success in industrial applications because of the limitation on system voltage (maximum 240 V) and the 6-mA maximum allowed leakage current. As a result, industrial personnel protection has been lagging behind its residential counterpart. UL realized this gap and defined new GFCI classes to specifically address personnel protection in industrial applications. UL 943C defines the requirements of special-purpose GFCIs that can be used on systems up to 600 V and allows for a leakage current of 20 mA. This article describes the UL 943C requirements and the newly defined GFCI classes. The difference between equipment ground-fault protective devices (EGFPDs) and GFCIs is also addressed. Finally, the application of a Class C GFCI in a pulp and paper plant is described.