How do I test if my RCD is working properly – Advice from Electriman, North London Electricians

How to Test Your RCD at Home

An RCD (Residual Current Device) is a life-saving safety switch fitted in your consumer unit (fuse box) or plugged into a socket. It detects tiny electrical faults and cuts power within milliseconds — fast enough to prevent a fatal electric shock.

The Simple Monthly Test

Every RCD has a TEST button, usually labelled 'T' or 'TEST'. Here's how to use it safely:

Before you test: Make sure any sensitive equipment (computers, recording devices, fish tanks with heaters) is turned off or unplugged, as the circuit will lose power briefly.

Press the TEST button firmly — the RCD should trip instantly and the switch will move to the OFF or middle position.

If it trips correctly: Press the reset button or push the switch back to ON. Your RCD is working.

If it does NOT trip: The RCD is faulty and must be replaced by a qualified electrician as soon as possible.

If it trips but won't reset: There may be a fault on the circuit. Try unplugging all appliances on that circuit and attempt to reset again. If it still won't reset, call an electrician.

What RCDs Protect You From

Electric shock — if you touch a live wire, the RCD detects current escaping to earth and cuts power in under 40 milliseconds.

Electrical fires — caused by insulation faults and leakage currents.

Types of RCD in Your Home

Consumer unit RCD — covers multiple circuits in

Need a qualified electrician in North London?

Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.