You've probably heard the term "ground fault" many times in relation to facilities electrical systems. Ground faults are low-level short circuits that may not be detected and interrupted by fuses or circuit breakers and thus require specialized protection. This month we'll review the basics of ground fault protection of personnel as provided by receptacle circuit Ground Fault Circuit Interrupters (GFCI). Next month, we'll do the same for ground fault protection of equipment.

A good ground path ensures that the enclosure remains at zero voltage with respect to other grounded objects. Should this path be broken or develop a high resistance at any point between the receptacle and the service, leakage current may energize the enclosure to a voltage approaching the 120-V line. If a person contacts the energized enclosure while touching or standing on a grounded surface, leakage current can flow back to the source through the body.