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4.4 Earth Fault Loop Impedance (EFLI)

Earth Fault Loop Impedance (max Ze) is the impedance of the earth fault current loop starting and ending at the point of earth fault.

The table below shows the maximum value of EFLI for new single and three phase supplies at the Point of Supply. 

 

System Service capacity Earthing terminal EFLI (at the customers supply terminals) 
230V single phase Up to 100Amp Cable sheath/continuous earth wire  0.8W
Up to 100Amp PME/PNB 0.35W
400V three phase Up to 100Amp Cable sheath/continuous earth wire  0.8W
Up to 200Amp Cable sheath/PME/PNB 0.35W
200-300Amp Cable sheath/PME/PNB 0.2W
Over 300Amp Cable sheath/PME/PNB 0.15W

All of the quoted values of earth loop impedance shown above are typical maximum values and the measured value of EFLI will change depending on the network configuration due to alterations, faults, maintenance and any embedded generation.

V1_December2015