What is the advantage of a double pole switch over a single pole switch?
On-off vs isolation switching

In the UK, a single-pole switch is usually used to turn on and off a light or an appliance. A double-pole switch is used where you need to isolate a circuit for safety reasons during maintenance of the circuit.

For example, current UK code requires a two-pole isolator for fire-alarm control-boxes and for high-power fixed-wiring (non-plugged) appliances such as isolation switches next to electric cookers and electric showers.




The issue is that, in case of a fault being investigated, the fault may have caused neutral to be broken or otherwise to be carrying a voltage significantly different from ground (earth).