RCD TRIPPING - ADVICE PLEASE

[AJT83]

Hi,

Recently got called to a job, a problem with the RCD tripping. Went through the usual procedures of unplugging everything however I realised it wasn't just tripping on one circuit. It trips if you turn the shower on, plug something into the cooker switch and if you plug something into the ring main. Did a ramp test on the RCD and got 27ma. Didn't have time to IR test as the customer was going out. Was hoping somebody could point me in the right direction for when I go back. I presume it's a Neutral - Earth fault but I just don't understand why it trips on 3 different circuits? Even just trying to get a ZS at a socket or the cooker switch trips it (obviously on no trip).

Customer did say they had a leak not so long ago though but don't see why that would cause a fault like this. The RCD just wouldn't reset if that was the case?

Thanks in advance

 

[Octopus]

shared neutrals matey .............................................

 

[AJT83]

It's a split board. Non rcd with just lights which are fine and an rcd side with shower, cooker and ring main. All breakers stay on and the rcd is fine running his boiler, tv, PlayStation etc but if I turn the shower on it trips, if I plug anything into the cooker socket it trips and likewise with the house sockets. If I try and get a ZS anywhere it trips!

It's worked fine for years apparently and not had any electrical work done recently.

 

[camerabloke]

Has it had ANY work recently?

 

[telectrix]

it's a N-E fault. appears when any load is applied to the RCD circuits.

 

[Richard Burns]

If it is that the RCD is tripping when circuits are drawing a high current, then that indicates the fault as described quicker by Telectrix .
There would be very little pd for current to flow down a (relatively) high resistance fault in stead of just down the very low resistance neutral and only a small proportion will make it through, but if the small proportion exceeds 30mA because the total load is high then the RCD trips.

 

[Dave OCD]

You need to separate the neutrals on the RCD protected circuits then test individually, I'd be certain just one of the circuits has a fault.

 

[buzzlightyear]

faulty RCD .

 

[AJT83]

Thanks lads. I was hoping somebody would tell me it wasn't a N-E fault though the house is rank and really don't want to spend any length of time in their!

 

[buzzlightyear]

Thanks lads. I was hoping somebody would tell me it wasn't a N-E fault though the house is rank and really don't want to spend any length of time in their!

so what is the conclusion .

 

[Dave OCD]

You could suddenly twist your ankle/sprain wrist or similar and ring them to say sadly you can't get there for 4 weeks or so.... Not that I condone such things of course.

 

[buzzlightyear]

You could suddenly twist your ankle/sprain wrist or similar and ring them to say sadly you can't get there for 4 weeks or so.... Not that I condone such things of course.

or you could say ,I might have the s**ts
for a few weeks .

 

[Dave OCD]

That would happen after working in a place like that for any length of time I suspect.

 

[buzzlightyear]

that reminds me .need to get my injection .for diphtheria next time I go the c**P job .

 

[Octopus]

Thanks lads. I was hoping somebody would tell me it wasn't a N-E fault though the house is rank and really don't want to spend any length of time in their!

Then ring them up and say you can't come back for a couple of weeks ....

 

[Octopus]

AND there could be 2 faults - one on a RCD protected circuit and another on a non RCD protected circuit!

 

[Deleted member 9648]

"Didn't have time to IR test as customer was going out"!!!!!
Mate that's the first thing you should have done. Farting about ramp testing and unplugging things, waste of time. Leave everything plugged in and do a 250v test LN-E. Five minutes will establish whether a fault is present. Only when you know what you are dealing with can you make an informed decision on how to proceed, then its time to start farting about unplugging things.
Sorry but it always leaves me open mouthed the number of electricians who come on here about tripping RCD's and haven't carried out IR tests.

 

[Deleted member 9648]

double post

 

[PEG]

"Didn't have time to IR test as customer was going out"!!!!!
Mate that's the first thing you should have done. Farting about ramp testing and unplugging things, waste of time. Leave everything plugged in and do a 250v test LN-E. Five minutes will establish whether a fault is present. Only when you know what you are dealing with can you make an informed decision on how to proceed, then its time to start farting about unplugging things.
Sorry but it always leaves me open mouthed the number of electricians who come on here about tripping RCD's and haven't carried out IR tests.

...You're gonna upset lad's who charge by the hour,with advice like that...

 

[telectrix]

Thanks lads. I was hoping somebody would tell me it wasn't a N-E fault though the house is rank and really don't want to spend any length of time in their!

bloody defeatist. ( and it's there, not their).