What is this?
Receiving a shock from a light switch means there is a fault allowing electricity to reach the outer parts of the switch that you touch. In a properly wired installation, the switch faceplate and toggle should never be live. This fault could be caused by a loose earth connection, damaged wiring behind the switch, or a cracked faceplate allowing contact with live terminals. Under BS 7671 (the UK wiring regulations), all exposed metalwork must be properly earthed to prevent exactly this kind of shock.
Common causes
- Loose or disconnected earth wire at the switch
- Damaged or deteriorated cable insulation behind the faceplate
- Incorrectly wired switch (DIY or poor workmanship)
- Cracked or broken faceplate exposing live terminals
- Moisture ingress in bathroom or kitchen switches
Is it dangerous?
Yes, this is dangerous. Any shock from a fixed installation like a light switch indicates a serious wiring fault. Even a mild shock means the earthing or protective devices are not working as they should. The shock could be much worse in different conditions — for example, if your hands are wet or you are standing on a damp floor. Do not use the switch until it has been inspected.
Can I fix it myself?
Do not attempt to fix this yourself. Turn off the lighting circuit at the consumer unit by switching off the relevant MCB, and leave the switch alone. Use a piece of tape over the switch as a reminder not to use it. If you are not sure which MCB controls the lighting circuit, turn off the main switch. Do not remove the faceplate to investigate — working on live or potentially live wiring without qualifications is dangerous and may not comply with Part P of the Building Regulations.
When to call an electrician
Call an electrician as soon as possible. A shock from a light switch is a high-priority fault. If the shock was severe or you feel unwell after receiving a shock, seek medical attention first and then arrange for an electrician to inspect the switch and the circuit it is on before using it again.
What will an electrician do?
Isolate the circuit and remove the switch faceplate to inspect the wiring
Check all connections including the earth conductor
Test the circuit for earth continuity and insulation resistance
Inspect the cable for damage, overheating, or deterioration
Replace the switch and any damaged wiring
Test the RCD to ensure it would trip in a fault condition
Typical cost
£80 – £180
A straightforward switch replacement with a wiring check is at the lower end. If the fault extends into the cable behind the wall, costs will increase.
