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Electric Shock From Radiator
You feel a shock or tingling when you touch a radiator or central heating pipe in your home.
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What's happening?
Feeling a shock from a radiator or heating pipe means electrical current is flowing through your central heating system's metalwork. Like shocks from taps, this is caused by a fault elsewhere that is energising the pipework. The metal radiators and pipes act as conductors, carrying the fault current throughout the house. This is especially common in homes where the cross-bonding between electrical earth and pipework is inadequate or missing.
What usually causes it?
- Missing or broken main earth bonding to the central heating pipework
- Faulty motorised valve, pump, or boiler leaking current onto the pipework
- Electric towel rail or radiator with an internal fault
- Damaged cable in contact with a heating pipe somewhere in the house
- Faulty immersion heater energising the hot water system and connected heating pipework
Is it dangerous?
This is dangerous and should be treated urgently. Metal radiators are large and easy to touch accidentally, especially for children. The fault current can be present on every radiator and pipe in the house. If the bonding is missing, the RCD cannot detect the fault, meaning there is no automatic protection against the shock.
Can I fix it myself?
Do not attempt to fix this. Turn off the mains electricity at the consumer unit. If you have an electric towel rail or electric radiator, check if the shock only occurs when that specific unit is on — if so, isolate it at its fused spur. Do not touch radiators or heating pipes with wet hands until the fault is resolved.
When should you call an electrician?
Call an electrician as soon as possible. This is a high-priority fault because it affects the entire heating system and could indicate missing bonding, which is a fundamental safety issue. The electrician may also recommend involving a heating engineer if the fault is in a boiler or motorised valve.
What will the electrician actually do?
- Test all radiators and pipework for voltage
- Check the main earth bonding and supplementary bonding connections
- Test the boiler, pump, and motorised valves for earth leakage
- Check any electric towel rails or radiators for internal faults
- Restore or install bonding connections as required by BS 7671
- Test the RCD to ensure it provides protection on the affected circuits
What will it cost to fix?
£100–£280
Bonding repairs are relatively straightforward and at the lower end. If a boiler component or electric radiator needs replacing, costs will be higher and may involve a heating engineer as well.
Find an electricianFrequently asked questions
We’re happy to answer all your questions.
Why am I getting a shock from my radiator?
A fault somewhere in your home is putting electrical current onto the metalwork of your heating system. The most common causes are missing earth bonding on the pipework or a faulty electrical component in the heating system like a pump or motorised valve.
Could it be the boiler causing this?
Yes. Boilers contain electrical components (pumps, valves, circuit boards) and if one develops an internal fault, it can leak current onto the pipework. An electrician and heating engineer working together can diagnose this.
What is cross-bonding?
Cross-bonding (or supplementary bonding) connects your gas pipes, water pipes, and central heating pipes to the electrical earth. This ensures that any fault current on the pipes is detected by the RCD and the power is cut off automatically.
Is this more dangerous in the bathroom?
Yes. Bathroom radiators and towel rails are often touched with wet hands or while barefoot on a wet floor, both of which dramatically increase the severity of a shock. This is why bathroom bonding requirements are particularly strict.
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