I'm investigating a control circuit that switches a heating element. From what I can see there is a relay on both the neutral and live to the heater. The relays are controlled together and cannot switch independently.
Is this common for controlling a heating element? What is the advantage of this over just a single relay across the live?
Best Answer
Yes it is normal to switch both poles of a mains circuit. That way, if the circuit is incorrectly wired (or plugged in, where 2-pole plugs are reversible!) you can be certain the circuit is not accidentally live when it is switched off.
What is NOT normal is to fuse both poles - if fuses are fitted, they should ONLY be in the live circuit, for hopefully obvious reasons.