Electric Boiler tripping off RCD?

Electric Boiler tripping off RCD?

11:20 AM, 8th February 2022, About A year ago 38

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Dear all, We have an electric boiler in a central London property. The boiler is over 4 years old and keeps tripping off the central heating circuit in the residual current device (RCD).

The property has been without hot water and heating for the past week. Our usual heating engineer has run some checks but couldn’t get to the bottom of the problem as they specialise in gas boilers.

We would be most grateful if anyone has run across this problem before and has any advice they can give.

There still seems to be far fewer experienced electric boiler engineers than gas boiler engineers. Although I assume this will change towards 2030 as gas bailers are phased out.

Thank you very much.


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paul kaye

11:57 AM, 8th February 2022, About A year ago

you need an electrician a gas engineer may not be qualified in electrics.
Also contact the makers of your boiler for advise.
You may well have wiring issues, tripping can be caused by faulty switches and or connections.
Any good electrician should be able to find the fault.


12:02 PM, 8th February 2022, About A year ago

We had an electric boiler fitted which has been a fantastic solution for us.....however, it is very important that the total capacity of electricity for your property (from the main meter) is properly assessed so that the boiler for it does not exceed that limit. We had to have a boiler that required slightly less electricity capacity than one we could have chosen, purely for this reason. Were you properly advised as the capacity of your meter in the first place, upgrading it is very expensive, but may be the route of the problem?


12:04 PM, 8th February 2022, About A year ago

That usually indicates that the heating element is failing. Presumably you could get a heating company to test the element and replace, shouldnt be very costly. Check on the price of a new element on the internet.


12:47 PM, 8th February 2022, About A year ago

Reply to the comment left by paul kaye at 08/02/2022 - 11:57
Paul, thank you very much for your pointing. I have been trying to find a good electrician -my usual one has come and was not confident to handle it. any recommendation covering central London would be most grateful.

Best wishes,


12:59 PM, 8th February 2022, About A year ago

Reply to the comment left by Wendy at 08/02/2022 - 12:02
Hi Wendy,

thank you so much for your response. I assume the total capacity for our flat is sufficient to handle the boiler as we have had the boiler for over 4 years and it had been working fine until a week ago - our boiler's maximum output capacity is 15kw but we only set it for 8kw due to the smaller size of our flat. The electrician at the time was happy with the arrangement.

Would you mind sharing with me the contact details of the installer you used for your electric boiler - He sounds very thorough and clued up. I am most grateful.

I took forward to hearing from you.

Thank you and best wishes,


13:00 PM, 8th February 2022, About A year ago

In my experience the majority of heating engineers do not have the experience to deal with "wet electric" heating systems (i.e. with radiators) and an electrician certainly will have little or no experience of heating systems, you MUST have a heating engineer thoroughly versed and possibly with the specific manuafatcurer, I have seen landlords have their time and money wasted by ther own actions and those of agents and their "usual people".


13:01 PM, 8th February 2022, About A year ago

Reply to the comment left by Timmo at 08/02/2022 - 12:04
Hi Timmo,

Thank you so much for your response and suggestion, all is noted and will do accordingly.

Best wishes


13:16 PM, 8th February 2022, About A year ago

We had a similar problem with our electric shower which had a higher wattage than the RCD could handle. We got an electrician to check the wiring and upgrade the RCD to a higher capacity.

Also the boiler should be on its own circuit with a dedicated RCD suitable for the boiler. So it is not the total capacity of the flat but rather the capacity of the circuit for the boiler that may be the issue.

As Timmo has suggested perhaps the heating element is failing and need replacing.


13:42 PM, 8th February 2022, About A year ago

Sorry on second thoughts if it is a boiler rather than a water heater it will probably need a new heat exchanger as the heating elements are probably not replacable. If that is the case the cost could be considerable.

Chris Byways

14:49 PM, 8th February 2022, About A year ago

If 4 years old, then chances are you’ve had an electric test since, so if that electrician was ok it might be worth asking him/her if they are familiar enough with electric boilers?

As said, it should be on its own rccb earth leakage but this may serve more than 1 mcb ie overload breaker. Any earth leakage from other circuits is cumulative, thus any circuit alone would be ok. Pound to a penny nothing to do with total load.

Also worth checking the correct earth leakage trip value. I had intermittent tripping of PV, electrician couldn’t locate a problem, so last resort (I think from a forum) I read manual. It had to be 100m/a not the normal 30m/a.

Any decent electrician should be able to check for earth leakage with a megger if safe, or 250 v but not a low voltage multimeter!

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