The principle of earthing is to consider
the general mass of earth as a reference (zero) potential.
Thus, everything connected directly to it will be at this
zero potential, or above it by the amount of the volt drop
in the connection system (for example, the volt drop in
a protective conductor carrying fault current). The purpose
of the earth electrode is to connect to the general mass
of earth.
With the increasing use of underground
supplies and of protective multiple earthing (PME) it is
becoming more common for the consumer to be provided with
an earth terminal rather than having to make contact with
earth using an earth electrode.
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