Editing AC power plugs and sockets (section)

=== Polarisation ===
Where a "[[Ground and neutral|neutral]]" conductor exists in supply wiring, polarisation of the plug can improve safety by preserving the distinction in the equipment. For example, appliances may ensure that switches interrupt the live side of the circuit, or can connect the shell of a screw-base lampholder to neutral to reduce electric shock hazard. In some designs, polarised plugs cannot be mated with non-polarised sockets. In most [[NEMA connector#NEMA 1|NEMA&nbsp;1]] plugs, for example, the neutral blade is slightly wider than the hot blade, so it can only be inserted one way. Wiring systems where both circuit conductors have a significant potential with respect to earth do not benefit from polarised plugs.