Grounding/Earthing Revisited

摘要

Earthing (grounding) cord-connected products creates an equipotential environment for personnel which provides protection against electric shock. The earthing scheme can be functional only, a principal safeguard, a supplementary safeguard, a reinforced safeguard, or a combination of these safeguards. The principal safeguard function returns protective conductor currents to their source and prevents touch current. The supplemental safeguard function returns fault current to its source, limits accessible part voltage, and enables installation overcurrent operation. The reinforced safeguard function eliminates the supplementary safeguard.