Qualities of Good Earthing

  • There are various formal definitions of a good Earthing, e.g., how many amp of current it can drain at a particular voltage, or resistance per surface meter.
  • Good Earthing must have impedance low enough to ensure that sufficient current can flow through the safety device so that  it disconnects  the supply ( <0.4 sec ) and that voltage of earth doesn’t rise more than 50V.

In simple theory this will prevent a potential difference between earth and earthed parts, as well as permitting the flow of fault current which will cause the operation of the protective systems.

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