See Section 2.7 for ground fault circuit interrupters for personnel protection. An increased degree of protection in solidly grounded systems can be achieved in providing ground-fault protection that will shunt trip circuit protective devices when user-selected levels of ground fault or leakage current flow are detected in electrical circuits. This is required to be installed on all solidly grounded wye services of more than 150 V to ground but not exceeding 600 V phase-to-phase where the service disconnecting means is rated at 1,000 A or more (See NEC Sections 215-10, 230-95, 240-13, and Figure 3-1).

4.15 PERSONNEL PROTECTIVE GROUNDS

Personnel working on or close to deenergized lines or conductors in electrical equipment should be protected against shock hazard and flash burns that could occur if the circuit were inadvertently reenergized. Properly installed equipotential protective grounds can aid in lessening such hazards by providing additional protection to personnel while they service, repair, and work on such systems.(See Section 7.5).

Figure 4-8. If the building steel, metal water pipe, concrete-encased electrode, and ground ring are available, they must be grounded and bonded to the service equipment to create the grounding electrode system.

4.15.1 PURPOSE OF PERSONNEL PROTECTIVE GROUNDS

Personnel protective grounds are applied to deenergized circuits to provide a low-impedance path to ground should the circuits become reenergized while personnel are working on or close to the circuit. In addition, the personnel protective grounds provide a means of draining off static and induced voltage from other sources while work is being performed on a circuit. (Figure 4-9 illustrates an example of a personnel protective ground.)