EICR Tested - 2 weeks on, RCD keeps tripping

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RMGL14

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Hi All,

I'm in the process of doing some light DIY (painting/cleaning) in a house I'm moving into (1930's, new wiring done 2014-ish)

It essentially is a shell ready to move in with the basic white appliances inside and nothing else.

I had the EICR tested 2 weeks back along with a boiler service/gas check on the same day.  
The only two C2's were 3.6 Water bonding has been snipped and not reinstated and C2 7 high reading on neutral on circuit 6, which seem to be unrelated to the issue I have.

One week after the EICR, I noticed an RCD tripped.  I then went to switch it back on and it popped.  I reset everything and managed to turn everything the supply back on and had no immediate issues.

Another week has passed and have used the heating/boiler, hoovers, other cleaning equipment and turned the fridge/freezer on etc with no issues. 

I've then connected the broadband and nest thermostat one evening and then left for the night.

During the night the RCD trips (I don't live at the property, but noticed the nest device disconnect during the night).

I've tried to reset the RCD, however it keeps tripping instantly. 

After trial and error turning on/off MCB's, I've narrowed it down to circuit 3 which feeds the ground level sockets and the boiler.

Nothing is plugged into the sockets and all of them are switched off. 

I want to try and identify whether it's the boiler that's causing the issue, however I cannot find a switch spur to isolate the boiler.

I can only see two unswitched fuse spur's side by side next to the boiler.

How do I isolate the boiler? Do I just pop out the fuse in the spur?  Also, why are there two unswitched fuse spurs side by side?

Many thanks for your help and insight.

 

RMGL14

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Remove the fuse from the unswitched spurs, small screwdriver in the chamfered edge should pop it out. 


Many thanks @Sharpend

Just to identify the scenario's.  If after isolating the boiler it continues to trip the RCD.  I'd imagine an electrician is needed to check whether there's N/E issues in the circuit/ring.  I already had a quick look behind the sockets for loose wiring, but couldn't identify any.

If however, it stops tripping.  Am I right in thinking I need a heat/boiler engineer to look at the issue, or does this still sit with an electrician?

 

Sharpend

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It would suggest something within the boiler but your dilemma is finding a wet head that knows how to test electrically inside and an electrician who knows what to test inside! 

 

RMGL14

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It would suggest something within the boiler but your dilemma is finding a wet head that knows how to test electrically inside and an electrician who knows what to test inside! 
I've removed both fuses from the unswitched spurs to isolate the boiler and it still trips.  I also removed the N and L on the load side of the spur, however still no luck.

This leaves just the sockets or the circuit itself as the problem.  Is there anything I can do to try and identify what could be the problem or is it last resort - call a sparky?

 

Sharpend

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Have you? Made sure power to sockets is off and then remove faceplates from the wall to check there are no stray cores loose in socket/terminal? 

Have you put up any pictures or shelves or had any other works done prior to fault appearing? 

 

SPECIAL LOCATION

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If you have a single RCD protecting multiple circuits you cannot isolate or prove any circuits at all,

without disconnecting either neutral or earth conductors from the common bars inside the consumer unit...

Turning off the Live supply to a circuit does NOT isolate that circuit from the investigations..

As ALL of the neutrals and earths are common inside the consumer unit..

RCD's will trip on BOTH Live->Earth faults, and Neutral->Earth faults..

i.e Power running through a perfectly good circuit..

can trip a common RCD due to a fault in another circuit..

Bottom line is without a full RCBO equipped consumer unit, there is always an element of "Piss-in-the-wind" with fault investigations..

(Some of your efforts may just spray back down over your trouser leg rather than reaching their target and proving nothing at all!)

Guinness  

 

RMGL14

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Have you? Made sure power to sockets is off and then remove faceplates from the wall to check there are no stray cores loose in socket/terminal? 

Have you put up any pictures or shelves or had any other works done prior to fault appearing? 
Yes - I checked removed all the faceplates to check for loose wiring.

The only thing I've done prior to the issue is install a door stop.  However, the screw was only long enough to go into the skirting.

 

RMGL14

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If you have a single RCD protecting multiple circuits you cannot isolate or prove any circuits at all,

without disconnecting either neutral or earth conductors from the common bars inside the consumer unit...

Turning off the Live supply to a circuit does NOT isolate that circuit from the investigations..

As ALL of the neutrals and earths are common inside the consumer unit..

RCD's will trip on BOTH Live->Earth faults, and Neutral->Earth faults..

i.e Power running through a perfectly good circuit..

can trip a common RCD due to a fault in another circuit..

Bottom line is without a full RCBO equipped consumer unit, there is always an element of "Piss-in-the-wind" with fault investigations..

(Some of your efforts may just spray back down over your trouser leg rather than reaching their target and proving nothing at all!)

Guinness  
Thanks for the insight.  I've attached a picture of the CU for reference.  So basically you're saying that even if circuit 8 is tripping.  It could be an issue with 9/7/6?

image.png

 

Andy™

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Thanks for the insight.  I've attached a picture of the CU for reference.  So basically you're saying that even if circuit 8 is tripping.  It could be an issue with 9/7/6?

View attachment 11636


does ciruit 8 actually trip though or just cause the RCD to trip when turned on? if it does trip then its most likely that circut. if it causes RCD to trip then its a good change its that circuit but not always

 

RMGL14

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does ciruit 8 actually trip though or just cause the RCD to trip when turned on? if it does trip then its most likely that circut. if it causes RCD to trip then its a good change its that circuit but not always
When I turn circuit 8 on, the RCD trips.
 

 

Phoenix

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I that case, there is no garentee that its circuit 8 at fault, but its at least somewhat likely...

If turning circuit 8 trips the RCD and the fault is *not* with cirucit 8, then it'll be being prompted to trip because of the loading that cirucit 8 brings on, if you were to unplug everything from cirucit 8 and it still does it then its probably more likely a fault with circuit 8, if it doesn't (asside from possibly being an issue with something you have just unplugged), or you can make it trip by adding load to another cirucit then thats an indication that the fault is likely anywhere (which could still include cirucit  😎

 

RMGL14

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I that case, there is no garentee that its circuit 8 at fault, but its at least somewhat likely...

If turning circuit 8 trips the RCD and the fault is *not* with cirucit 8, then it'll be being prompted to trip because of the loading that cirucit 8 brings on, if you were to unplug everything from cirucit 8 and it still does it then its probably more likely a fault with circuit 8, if it doesn't (asside from possibly being an issue with something you have just unplugged), or you can make it trip by adding load to another cirucit then thats an indication that the fault is likely anywhere (which could still include cirucit  😎
I've switched 9/7/6 off and turned on circuit 8 on it's own and it trips the RCD.  I've also ensured all sockets are off and unplugged.
I'll leave it to an electrician.  I hope it's an easy one to fix...

 

RMGL14

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Just an update - had the electrician in.  There was a high resistance between L/E on one of the cables in the ring.  Split the circuit up to solve the issue.
 

 

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