RCD Aways tripping

[telectrix]

Can't see any reason for supplementary bonding. Division of circuits across rcds seems fine to me. What is this zoning business? The hall lights are hall lights not a hallway. It is almost certainly crossed neutrals though.

unkess a builder has been "having a go".then anything is possible.

 

[Deleted member 9648]

I don't do EICR's, as I feel my level of experience would not enable me to scrutinise an installation to the correct degree. And I do not wish to take additional responsibilities at my age . I also do not wish to have the additional indemnity insurance, although I expect that would be an additional few pounds a month.

However, with just a few lines from the OP, bonding metal tables, bonding hot water tank etc, I would just question his experience in carry out an EICR, if infact that is what is doing.

OP, not having a go at you and we are all can learn from each other, but do you think you should be doing this sort of work on your own, with your current level of expertise? If things do go wrong, your insurance might not protect you. Just saying.

I do EICR's....been in the trade for getting on for 40 years....and am increasingly thinking they aren't worth the worry. The risk of missing something that'll come back to bite you seems very real to me. I think these obviously inexperienced guys carrying out EICR's are playing with fire.

 

[westward10]

I do EICR's....been in the trade for getting on for 40 years....and am increasingly thinking they aren't worth the worry. The risk of missing something that'll come back to bite you seems very real to me. I think these obviously inexperienced guys carrying out EICR's are playing with fire.

Couldn't agree more but like you I have been carrying out Periodics for years, you do the job to the best of your ability using your experience you have gained over the years. Unfortunately people who lack experience will do the job to the best of their experience and very often this isn't enough.

 

[Octopus]

You need to make an assessment of the earth leakage, across ALL the circuits and the effect that turning off circuits has.

Last Summer I was tracking an issue on a high integrity board - it had 2 x RCD's and 2 x RCBO's - one of the RCBO's was tripping - (it covered lights and smokes ONLY) but would ONLY trip when the kitchen was used.

Using my earth clamp meter I could see that as more appliances were used in the kitchen, RCBO2 would trip - I eventually found a fault on the RCBO circuit - as soon as that was cleared the RCBO tripping stopped.

The earth leakage from the cooker remains..... until they replace it!

So there may be more to this than meets the eye.

 

[HappyHippyDad]

Some of the more experienced chaps have said 'shared neutral', I can't see how this is possible so must be missing something? Doug says it trips when a 'significant load' is placed, if it was a shared neutral between rcd1 and 2 then it would trip immediately when anything on the circuits 2/3 on RCD 1 is used. Also, it would be a bit of a coincidence that circuits 2 and 3 have a shared neutral as well?

Doesn't it sound more like an accumulation of earth leakage? Richard Burns had a good diagram showing how a fault on one RCD could still cause the other RCD to trip (not a shared neutral).

 

[westward10]

I think crossed neutrals is the immediate default, said it myself. But as you say it may not be the case.

 

[Midwest]

Richard Burns had a good diagram showing how a fault on one RCD could still cause the other RCD to trip (not a shared neutral).

I was going to mention that (RB advice), but modesty got the better of me

 

[Richard Burns]

With a neutral earth fault on a circuit some current can be redirected from other circuits through the RCD protecting the circuit that has the neutral earth fault causing it to trip.
If only a small amount of current is diverted then only a large current loading on the other circuits could cause the trip.

Possibly this or this diagram?

 

[dmxtothemax]

Circuits 2&3 have a poor neutral somewhere,
causing some of that neutral current to find a path thru the other side
which must have a better neutral.
Check ALL neutral and earth connections.
you could try using an IR camera, look for hot spots.