Figure 3-1. Ground-fault protection shall be provided with 277/480-V

DOE-HDBK-1092-2004

A GFPE is defined in Article 100 of the NEC as a system intended to provide protection of

equipment from line-to-ground fault currents. GFPE systems (equipped with or without a test

panel) shall be inspected and tested at installation and at specified intervals as recommended

by the manufacturer.

Figure 3-1 shows a zero-sequence type of ground fault protection.

NEC 230.95

NEC 230.95 (A)

Figure 3-1. Ground-fault protection shall be provided with 277/480-V, three-phase,

four-wire services with over current protection devices of 1,000 A or more. A ground

fault sensor (window) can be used to encircle all service conductors, including the

grounded conductor (neutral).

Inspections, tests, and servicing shall be performed by personnel who are qualified for the work

to be performed. These qualifications can be shown by appropriate documentation of work

experience, on-the-job, and offsite formal training to verify understanding and retention of

minimum knowledge, skills, and abilities.

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