It refers to a set of cables(Phase/live and neutral) with a consumer protective circuit (earthing cable) bunch together in one sheathing, it is commonly used in domestic dwellings because it's cheaper and more compact
oi mate, give me 100 meters of 2.5 mill twin and earth.

nah mate, use the twin and earth for that circuit.
by Kurt (Mr Simplicity) December 15, 2007
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