Replace a metal-clad socket in a garage like-for-like

Turn off the power, swap the metal-clad socket like-for-like, then test it before switching back on.

GS-01Buy the right replacement socket and gather your toolsMatch the old metal-clad socket exactly: same current rating, same number of gangs, and same IP rating if it's exposed to the weather. Take a photo of the old one to the shop if you're unsure. You'll need a screwdriver set, a voltage tester, wire strippers, and a torch.

1 each · Metal-clad socket (13A, switched, double)

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1 each · Voltage tester (two-pole)

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1 each · Screwdriver set

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1 each · Wire strippers

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GS-02Turn off the power and prove the circuit is deadCheck the consumer unit labelling to find the circuit feeding the garage, then switch off that MCB or RCBO. If you're not confident which one it is, turn off the main switch instead. Prove the socket is dead with your voltage tester before touching any wire - test the tester on a known live first, then the socket, then the tester again.

1 each · Torch

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GS-03Remove the old faceplate and photograph the wiringUndo the two fixing screws and ease the metal faceplate off the back box - it can be stiff with paint or grime. Before you move anything else, take a clear, well-lit photo of the terminals showing which wire goes where. This photo is your guide for wiring the new socket the same way.

GS-04Disconnect the old socket and check the earthingLoosen each terminal screw and free the conductors one at a time, keeping them in the order you photographed. Look for a short earth strap or tail running from the back box itself to the earth terminal - metal-clad boxes need this to earth the metal casing. Keep the strap; you'll reuse or replace it.

1 each · Green/yellow earth sleeving

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GS-05Check the back box and replace it if damagedIf the metal box is corroded, cracked, or the cable entry grommet has perished, replace it now. Undo the fixing screws holding it to the wall and lift it clear, feeding the cable through gently so it isn't strained. If the box is sound and firmly fixed, leave it in place and move straight to the next step.

1 each · Replacement metal back box

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GS-06Work out what's behind the wall and choose the right fixingGarage walls are usually solid brick or block, but some are timber-stud or plasterboard-on-stud. Tap near the box - a dull solid sound is masonry, a hollow sound is a stud wall; if it's hollow, run a stud detector or magnet along the wall, and a small pilot hole confirms it: timber dust means a wood stud, fine grey swarf means a metal stud. Cables and pipes can run almost anywhere, so use a detector but still assume something's there - find your stopcock now and check it turns, and make sure the circuit is still isolated at the consumer unit before you drill. In solid brick or block, drill a 6mm hole 35mm deep and use a wall plug with a No.8 screw. In a timber stud, drive a 40mm wood screw straight into the centre of the timber - no plug needed. In a metal stud, never use a wall plug or wood screw, it strips straight through the 0.5mm steel - use a self-drilling metal-stud screw or a toggle-type hollow-wall anchor rated for the box's weight instead.

1 each · Cable and pipe detector

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1 each · Stud detector or magnet

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1 pack · Wall plugs and No.8 screws (35mm), pack

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1 pack · Wood screws 40mm, pack

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1 pack · Self-drilling metal-stud screws, pack

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1 pack · Toggle-type hollow-wall anchors, pack

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GS-07Fix the back box to the wallScrew the back box to the wall using the fixing you chose in the last step, feeding the cable through the entry grommet as you go. Keep the box square and flush with the wall so the new faceplate will sit flat. Don't overtighten plasterboard fixings - they can crush the board or strip a toggle.

GS-08Wire the new socket, matching your photoStrip and prepare each conductor to the length shown in the socket's instructions, then connect line to L, neutral to N, and earth to E exactly as before. Reconnect the earth strap to the back box so the metal casing is properly earthed - the UK wiring regulations require exposed metalwork like this to be earthed. Push each wire fully home and tighten the terminals firmly, then give each one a gentle tug to check it's secure.

RULES

KNOW THE RULES

BS 7671 (the UK Wiring Regulations) requires exposed metal enclosures, such as a metal-clad socket box, to be properly earthed. Don't leave the earth strap disconnected.

GS-09Fit the faceplate and tidy the cablesFold any spare cable neatly into the back box so nothing is pinched, then push the faceplate onto the box, checking no bare copper is showing anywhere. Fit the two fixing screws and tighten until snug. Don't overtighten - metal-clad plates can crack their gaskets.

GS-10Restore the power and test the socketSwitch the circuit back on at the consumer unit and check the RCD or RCBO hasn't tripped. Plug in a socket tester or a lamp to confirm the socket works and is wired correctly - a plug-in tester will flag reversed polarity or a missing earth straight away. If anything seems wrong, switch off again and recheck your connections against your photo.

RULES

1 each · Plug-in socket tester

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KNOW THE RULES

Replacing a socket like-for-like is not notifiable work under Part P of the Building Regulations, so no building control sign-off is needed. If you'd added a new circuit or moved the socket to a new position, that would be different.

GS-11Tidy up and dispose of the old socketSweep up any dust or debris from drilling and wipe down the wall. Take the old metal-clad socket to a household recycling centre - it's electrical waste and shouldn't go in general rubbish. Store any spare fixings in a labelled bag in case you need them again.

KNOW THE RULES

Before you start: Which electrical jobs can I do myself? Part P explained

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