External earth loop impedance

For many installations the resistance of the earth electrode can be measured using an earth fault loop impedance. Please note this test is carried out with only the exte. Of all the tests that contractors routinely perform on electrical installations, earth loop impedance testing creates the most confusion and uncertainty. The first is Ze, the external fault loop impedance , which is typically measured at the distribution board or consumer unit where the supply enters the building.

It is the measured resistance of the supply transformer winding, the supply phase conductor, and the erath return path of the supply.

Ze` can be obtained by enquiry to the electricity supplier or by direct measurement at the supply.

Internal loop measurements should be taken at points furthest from the intake to give the .

This method will give us the lowest earth fault currents to . Continuity of protective conductors including main and supplementary equipotential bonding. Tests with the electrical supply connected. It can be very inconvenient if an RCD is tripped by accident. Loop Impedance Testing - Duration: 15:04. Comments are disabled for this video.

Autoplay When autoplay is enable a suggested video will automatically play next. External earth loop impedance (Ze) test - Duration: 2:20. Obviously with parallel earth paths would reduce the resistance and increase the fault current. Connect the tester to the main earth and the live conductor. Earth electrode and earth loop impedance testing Theory and applications - As two of the most common testing subjects debated amongst electricians.

Where: Zs = earth fault loop impedance , Ω Ze = external earth fault impedance, Ω Z= line conductor impedance, Ω Z= Circuit Protective Conductor (CPC) impedance, Ω. The external impedance, Ze depends on the upstream network. The maximum prospective fault . Where an external meter box is fitte this is owned (and should be maintained) by the customer. Zs), or the earth -fault loop impedance external to the installation (Ze) may be measured at the supply position. The following values are typical for . Loop impedance , why it matters and typical values.

The supply to the dwelling is PME. Before any testing is carried out, a detailed physical inspection must be made to ensure that all equipment . Consequently, there are two values for the external earth fault loop impedance , Ze. This may be designated as Ztx , or something similar, to avoid confusion with Ze at the origin. Theoretically, these two readings . For three-phase installations, the highest reading obtained is recorded as the external earth fault loop impedance. Reconnect the earthing conductor to the MET.

The installation supply may be switched back on if required.