Check a socket with a plug-in tester

Use a plug-in socket tester to check wiring faults in seconds, room by room, with no tools needed.

SC-01Buy a plug-in socket testerGet a multi-LED socket tester from any DIY shop or electrical wholesaler, ideally one with a built-in RCD test button. It plugs straight into a standard 13A socket and reads the wiring behind it using a pattern of lights.

1 each · Plug-in socket tester (with RCD test button)

Buy:ScrewfixB&QToolstationAmazon

SC-02Look at the socket before you test itUnplug anything already in the socket. Check the faceplate for cracks, scorch marks, brown staining or a loose feel when you push a plug in. If you see any of this, or smell burning, do not test it — turn off the circuit at the consumer unit and get an electrician.

SC-03Plug in the testerPush the tester firmly into the socket, the same way you would a normal plug. Make sure it's seated flat against the faceplate. If the socket has a switch, turn it on.

SC-04Read the light patternCompare the lit LEDs to the chart printed on the tester or its packaging. A correct pattern means live, neutral and earth are all present and wired the right way round. Common fault patterns show a missing earth, no neutral, or live and neutral reversed.

SC-05Test the RCD button if fittedIf your tester has an RCD test button, press it. This should trip the RCD in your consumer unit within a second, cutting power to that circuit. If it doesn't trip, the RCD may not be protecting that socket properly.

SC-06Reset the RCD and carry on testingGo to the consumer unit and flick the tripped RCD switch back to on. Then move the tester to the next socket and repeat steps 3 to 5 for every socket you want to check, working room by room so you don't miss any.

SC-07Write down any faults you findNote the room and socket for anything that doesn't show the correct pattern, or an RCD that didn't trip. A single fault often points to a loose connection at that socket or further back in the circuit, not a fault with the tester.

SC-08Don't fix wiring faults yourselfA missing earth, reversed wiring, or a failed RCD test are jobs for a qualified electrician, not a DIY fix. Stop using any faulty socket until it's checked.

RULES

KNOW THE RULES

Under Part P of the Building Regulations, most fixed wiring work in England and Wales — including fixing faults found here — must be done by a registered competent person or notified to building control. Testing with a plug-in tester is not notifiable work; repairing the wiring is.

SC-09Tidy upUnplug the tester and store it somewhere handy — it's worth keeping for a quick check whenever you move into a new place or buy a new appliance. Put your notes somewhere you'll find them if you call an electrician.

Some links may earn us a small commission at no extra cost to you.

Save this as a project

Back to all guides