Earth fault loop impedance (electrical abbreviation Ze), is the path followed by a fault current when a low impedance fault occurs between the phase conductor and earth, i.e. “the earth fault loop”. The higher the impedance, the lower the fault current will be and the longer it will take for the circuit protection device to operate. So in summary, it is the impedance of the earth fault current loop starting and ending at the point of earth fault.
Typical earth fault loop impedance values at the point of supply are detailed in Table 4-3 of standard EDS 08-2000 for metered connections and Table 7-1 in standard EDS 08-2102 for unmetered connections. These can be accessed via the Design and Planning category of our G81 Library which can be accessed by clicking on the link here.
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