Modern single-phase UK wiring commonly identifies line with brown, neutral with blue and protective earth with green-and-yellow. Older red/black identification can remain, and a switch-drop core can be re-identified for a different role.

The diagram shows one flat twin-and-earth cable construction. Not every appliance cable contains three insulated cores: two-core flexes, other cable types and different circuits exist. Keep wiring closed; its colour, age or appearance does not establish a safe connection or absence of voltage.