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INSULATION TESTING ON LIVE CIRCUITS – THE SAFE WAY | ECASA
INSULATION TESTING ON LIVE CIRCUITS – THE SAFE WAY It's a familiar scene: An electrician is called out to deal with an electrical fault that's shut down sections of an installation or, worse, an entire installation. The electrician finds the residual current device (RCD) has tripped and when he closes it, it trips again. Wayne Ternent, Managing Director at Major Tech, explains, "An RCD senses an imbalance between the phase and neutral currents in the circuits; however, a possible path the leakage current may take is through the phase/earth insulation resistance and, hence an insulation test would be necessary. "An insulation test to trace the fault would mean separating the various lines and disconnecting appliances from the installation. To minimise downtime on the installation and to reduce the possibility of damage to sensitive electronic equipment, caused by high voltage generated by an insulation tester, the electrician uses a leakage clamp meter," he says, adding that when it