Electric Shock From Light Switch

What's happening?

The switch plate or toggle should not give a shock. A shock means something is wrong, but the feeling does not name the failed part. Possible causes include a loose connection behind the switch, damaged cable, a cracked plate, or moisture. A metal plate may be connected to the installation earth, in which case a supply fault can raise its voltage, or that earth connection may be missing. Testing is what sorts those apart.

What usually causes it?

• A loose connection or damaged cable behind the switch
• A cracked plate that lets a finger meet a live terminal
• Moisture in a kitchen or bathroom switch
• A metal plate sitting at the same voltage as a supply earth fault
• A fault elsewhere on the same circuit

Is it dangerous?

Yes. Wet hands or a damp floor make the same fault worse. A brief tingle is still current through the body. HSE says a residual current device (RCD) detects some faults, not all, and a shock can still be serious. Call 999 if someone is unconscious or not breathing normally, and do not touch them while they are still on the switch. If they seem well, still get a medical assessment: Electrical Safety First says injury, including a disturbed heart rhythm, may not show at once.

Can I fix it myself?

Do not take the faceplate off or try the switch again. Switch off that lighting circuit, or the main switch if you cannot tell which breaker it is, only if you can reach and operate it without touching suspect metal or standing in water. If you are not sure, keep away and call. Keep the switch unused. If taps, radiators or other metalwork give a shock as well, call 105 in England, Scotland and Wales as well as an electrician: the main switch does not clear a supply fault on bonded metal. Tell them which switch, whether the shock was brief, whether any breaker moved, and whether anyone is hurt.

When should you call an electrician?

Have an electrician test the switch and circuit before it is used again. Call 105 as well when the shock is on metal fittings in more than one place.

What will the electrician actually do?

• Prove the circuit dead, then inspect the switch without asking you to reproduce the shock
• Test the connections, the cables and the earth continuity
• Check whether other lights or metal fittings on that circuit are affected
• Replace only the parts the tests show are damaged
• Check whether protective devices operated, without treating a device that stayed on as proof there was no fault

Who fixes this

• Emergency electrician
• Electrical fault finding

What it usually costs

Emergency Electrician Cost

£80–£100 / hour

Electrical Fault Finding Cost

Priced on survey

Questions people ask

Sources & References

1. Electrical Safety First: first aid for electric shock
2. HSE: work using electrically powered equipment (RCD)
3. IET: Broken PEN
4. St John Ambulance: electric shock