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Hi All

I wonder if somebody can help.

In our domestic CU one of the RCD's keeps tripping out without any of the MCB's tripping. When I reset the RCD it resets fine without any problems. All is ok for an intermittent period (could be days or hours and it trips again).

I think from the forum this is indicating a N-E fault and I need to maybe do some investigative work on each of the MCB protected circuits to try and diagnose which appliance (if any) is causing the problem. However I'm not sure if that will diagnose the issue as I've learnt the RCD shares a neutral bar with all of the affected circuits. Basically I'm not sure of the most logical way to go about doing the testing.

The RCD usually resets fine without any MCB tripping, however a couple of times one of the MCB's tripped when I reset the RCD (The circuit included some downstairs sockets/fridge/oven/alarm). The MCB reset fine though and I'm wondering if this was a red herring as only the fridge and house alarm were on at the time.

This is a new house build with full electrical certifications and only two years old. I don't want to call the electricians out for a simple fix.Any ideas please?

Thanks
 
Might not be a neutral fault, may just be an appliance that is breaking down. Such as a compressor on a fridge/freezer, heating element going in a kettle or water tank. Washing machine, tumble driers are another good culprit.

Not only that but you could have a few items with cumulative earth leakage that's leaking just enough combined to go over the RCD's threshold.

Have you noticed any correlation between when it trips and you undertaking certain tasks?

Unfortunately intermittent faults can be a real pain to find even with proper test gear.
 
I had this issue a few months back, happened when turning the oven in cooker on, the heating element was on its way out. RCD would trip within seconds of me turning it on. cost of finding a suitable part and time involved, i just popped along to curry's and bought a new one.
I would say turn MCB's off leaving just one on and then go round unplugging things. eventually you will likely find the offending device
 
Thanks for the replies.

JCB option might have wait for the moment!

No pattern I'm afraid. Just come back from hols and switched most of the sockets off before I went. Only the fridge and house alarm were connected really to the possible 'faulty' MCB circuit. Came back to find the RCD tripped.

Can somebody suggest a test procedure please. Should I be disconnecting Neutral sides of MCB's etc to try and diagnose?
 
You could find the offending circuit by removing neutrals but it would only indicate which circuit if the fault was there continuously

I will stick my head on the line here and suggest your fridge is causing the tripping when its compressor is switched into use

If you were to run this suspect appliance(or any other for that matter) from a socket fed by the other Rcd (using an extension lead) and see if you can get an appliance to cause the other Rcd to trip.it will be a process of elimination but you should get there
Does this Rcd also supply a light circuit with a outside light perhaps
 
Unless you know that you have double pole sockets, just switching off may not prove anything. Bouble pole sockets break both the live and the neutral conductors, single pole only the live so would still leave the neutral connected.
 
Your best course of action IS to keep a log of when it happens ......... then when you call a sparky in, they will have something to go on.............................

BUT I warn you it could be accumulated earth leakage so random appliances could push this over the threshold for the RCD....

What the other have said all apply too.
 
Hi All

I wonder if somebody can help.

In our domestic CU one of the RCD's keeps tripping out without any of the MCB's tripping. When I reset the RCD it resets fine without any problems. All is ok for an intermittent period (could be days or hours and it trips again).

I think from the forum this is indicating a N-E fault and I need to maybe do some investigative work on each of the MCB protected circuits to try and diagnose which appliance (if any) is causing the problem. However I'm not sure if that will diagnose the issue as I've learnt the RCD shares a neutral bar with all of the affected circuits. Basically I'm not sure of the most logical way to go about doing the testing.

The RCD usually resets fine without any MCB tripping, however a couple of times one of the MCB's tripped when I reset the RCD (The circuit included some downstairs sockets/fridge/oven/alarm). The MCB reset fine though and I'm wondering if this was a red herring as only the fridge and house alarm were on at the time.

This is a new house build with full electrical certifications and only two years old. I don't want to call the electricians out for a simple fix.Any ideas please?

Thanks
Are you suggesting he should be digging for this fault himself
No if I know Tel like I think I know him he means knock the gaff down and start over, I think, Tel!!!
 
I think he did mean know the gaff down!!!

Not sure if I have double or single pole sockets, will have to check. I will keep a log and follow the test procedures suggested - thanks.

There are some outside sockets IP66 standard on the circuit.
 
Yes I can. They are on a switched connection so I can turn off just the outside sockets from inside. I only put them on when required as they are at the front of the house. They have been off every time RCD trips.
 
You could find the offending circuit by removing neutrals but it would only indicate which circuit if the fault was there continuously

I will stick my head on the line here and suggest your fridge is causing the tripping when its compressor is switched into use

If you were to run this suspect appliance(or any other for that matter) from a socket fed by the other Rcd (using an extension lead) and see if you can get an appliance to cause the other Rcd to trip.it will be a process of elimination but you should get there
Does this Rcd also supply a light circuit with a outside light perhaps

Agree with Des, that fridge is the first thing I'd rule out, before trying anything else.

Nice track by the way Pete :cool:
 
A bit of a drastic action to resolve a fault.
the idea behind the post was that it would not only solve his electrical problem, it would also fix the many issues of a new build, e.g. dry lining, weetabix floors, unseasoned timber, wonky roof trusses that bar access to attics,, 3 tons of insulation, studded walls, and all the other cheap and nasty practices that came in on the 1960's and 1970's, along with mowtown, and rapp "music".
 
the idea behind the post was that it would not only solve his electrical problem, it would also fix the many issues of a new build, e.g. dry lining, weetabix floors, unseasoned timber, wonky roof trusses that bar access to attics,, 3 tons of insulation, studded walls, and all the other cheap and nasty practices that came in on the 1960's and 1970's, along with mowtown, and rapp "music".
If you think they were bad then you should see some of the new builds done now !.
 
QUOTE - [ They have been off every time RCD trips.

If power goes to the light fitting and then via a switch loop,
then moisture can still get in and cause problems even when the switch is off !
 

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