Discuss Intermittent RCD tripping. Benefit of changing over to RCBO's? in the DIY Electrical Forum area at ElectriciansForums.net

mc1903

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Hi,

We have recently had some electrical work completed in the house to add a new circuit for air conditioning.

We are now experiencing intermittent RCD trips, at all hours of the day and night, in the section of the consumer unit that the new A/C MCB was installed into.

No MCB's trip - just the common RCD.

I have a non-electrical technical background and understand that fault finding intermittent issues is usually a complete nightmare. I work from home and I am losing money/reputation each time the RCD trips and I get kicked out of a client call.

I am after professional opinion on the actual benefit of changing out all of the MCB's/RCD's for RCBO's and, if there is a real benefit, what a fair ball park cost & hours/days to complete would be? What 'paperwork' should I ask for/expect as part of any remedial electrical works, to cover me from a home insurance position?

Picture of consumer unit attached.

Thanks in advance.
M
 
TL;DR
Random RCD trips after new MCB installed. Cannot live with the issue, so should I just replace all of the MCB's & RCD's with RCBO's.

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SJD

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Somewhat odd to have all the lighting on one RCD, and all the sockets on the other - normally they would be divided across each RCD to minimise inconvenience in the event of a trip.

I was going to say in the meantime make sure critical items like internet router are plugged into sockets on the non-tripping RCD, but of course you can't do that due to the way the board has been installed.
 

mc1903

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Somewhat odd to have all the lighting on one RCD, and all the sockets on the other - normally they would be divided across each RCD to minimise inconvenience in the event of a trip.

I was going to say in the meantime make sure critical items like internet router are plugged into sockets on the non-tripping RCD, but of course you can't do that due to the way the board has been installed.

🙁 Lol... we thank George Wimpey almost everyday for something else we find wrong with our house.

GW only seem to care to minimise inconvenience to themselves during the build; the punter (me) is a secondary consideration!

Any thoughts on RCBO's?

Cheers
M
 

SJD

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As mentioned by UNG, simplest option is likely swap circuits around, and just put anything critical or problematic on its' own RCD, if the board can be configured to do that. A complete board change with all RCBOs like to cost £600 to £1000 or more, depending on brand, your location and how expensive a quote you get.
 

mc1903

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If the CU can be reconfigured just add an RCBO for the A/C and may be reconfigure / swap around some of the circuits to give a better split across the 2 RCD's

So could I have a mix of MCB's/RCD's and RCBO's in the same CU?

In a professionally installed CU, should there usually be enough length on the various wires to move things around?

I use the word professional cautiously in respect of the house builder 😀😀

Thanks
M
 

mc1903

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As mentioned by UNG, simplest option is likely swap circuits around, and just put anything critical or problematic on its' own RCD, if the board can be configured to do that. A complete board change with all RCBOs like to cost £600 to £1000 or more, depending on brand, your location and how expensive a quote you get.

Thank you both @SJD & @UNG - £600-£1000 seems a bargain if it solves or at least narrows down where the issue is. I have spent about 15x that on A/C that I now have isolated to see if it IS the issue.
 

UNG

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Thank you both @SJD & @UNG - £600-£1000 seems a bargain if it solves or at least narrows down where the issue is. I have spent about 15x that on A/C that I now have isolated to see if it IS the issue.
The £600 - £1000 would be for a complete consumer unit swap a bit of reconfiguring of the existing unit would be likely to cost no more than £250
 

littlespark

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There can be many reasons why rcd’s trip out, and having all the sockets on the one rcd will cause trouble.

a small earth leakage on anything from the fridge compressor to a number of phone chargers etc may not be a problem on their own, but added together could exceed the 30mA threshold.

simplest thing to try first is swap a few circuits between sides and see if that sorts things.

It’s not a DIY job though....
 

mc1903

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There can be many reasons why rcd’s trip out, and having all the sockets on the one rcd will cause trouble.

a small earth leakage on anything from the fridge compressor to a number of phone chargers etc may not be a problem on their own, but added together could exceed the 30mA threshold.

simplest thing to try first is swap a few circuits between sides and see if that sorts things.

It’s not a DIY job though....

Thank you @littlespark

The current configuration of the CU was down to the builder/their electrical contractor. House was built in 2007, I assume the way things are done now is different from back then; but even so, putting all sockets on one RCD seems daft, now that I understand it a little more.

I have had a quote to completely replace the CU with "1 x 18th edition 14 way consumer unit with individual RCBO protection" and it is close to the top end of the estimate range @SJD gave earlier.

I am waiting on another company to visit and give me their advice, but rest assured I will be going nowhere near the CU with tools myself. I know my limits. 👍
 

UNG

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The current configuration of the CU was down to the builder/their electrical contractor. House was built in 2007, I assume the way things are done now is different from back then; but even so, putting all sockets on one RCD seems daft, now that I understand it a little more.
The way it should have been done hasn't changed at all and is no different now to how it was back in 2007
 

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