Earth Fault Loop Impedance (EFLI)
[ Last Updated 27 March 2006 ]
Q. What are the Requirements for EFLI Testing Inside an Installation?
A. AS/NZS 3000 requires protective devices to operate within 0.4 seconds. Either a circuit impedance calculation or an EFLI test can verify the operating time. However, regulation 53 limits the voltage drop to less than 5%. Generally if this is being achieved, and an MCB has been used, then the 0.4 seconds will be achieved. For long cable runs or where the volt drop is approaching 5%, the operating time will need to be verified.
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