RCD tripping problem

[Blue Fox]

Been to change a consumer unit today. But I have an RCD that keeps tripping out. It will sit there for a couple of minutes then trip or if you turn on 2 particular lights it will trip and again if you plug in the fridge freezer but not if you plug another appliance into the same socket. All tests out ok with insulation resistance on circuits but can't seem to find fault. Tried swapping the RCD's but still same. Its tripping on the kitchen ring and the kitchen lights. Customer has had a new kitchenette put in a couple of years ago and said he wasn't very happy with the work when it was put in - he had loads of problems with it.

Anyone got any ideas or is it just going to be a case of a working through it. Have agreed to go back on Sunday as am busy next week and can't leave them without power in kitchen for that long.

 

[Oracle]

hi,

Have you done a ramp test?

Have you measured earth leakage?

Identify which circuit it is (could be both) - check each appliance, or test by splitting the ring, etc.

O.

 

[batty]

Get back to basics, how many circuits go through the Rcd. When you tested insulation resistance was everything unplugged.

Batty

 

[patspark]

hi could be anything check for borrowed neutrals or neutrals on the wrong

bar.

it sounds like 2 faults the fridge freezer as the rcd does not trip

with something else plugged in to the socket.

i would eliminate that first

 

[M107]

Had the same sort of problem last year (the post is on here somewhere)

Tracked the fault down to a faulty pool heater plugged in outside, not enough to drag the rcd down on it's own but was as soon as any appliance was plugged in & turned on.

Got another rcd fault today but thats another post on it's way.

 

[Apache]

Had the same sort of problem last year (the post is on here somewhere)Tracked the fault down to a faulty pool heater plugged in outside, not enough to drag the rcd down on it's own but was as soon as any appliance was plugged in & turned on.

Got another rcd fault today but thats another post on it's way.

this one?

 

[M107]

Well done patch thats the one.

 

[Blue Fox]

With nothing plugged into any sockets it still trips after a couple of minutes. Think the fridge freezer is definatly at fault but there is something else there somewhere. Thinks its just going to be a matter of working throught it just think its going to be a long day.

 

[Blue Fox]

this one?

Patch are you a real person or are you a computer search engine for threads on this site!! Ha Ha

Everything on circuit was unplugged when ins testing.

This is also the house with no cpc on the lighting circuit as mentioned in previous threads.

 

[batty]

Patch are you a real person or are you a computer search engine for threads on this site!! Ha Ha Everything on circuit was unplugged when ins testing.

This is also the house with no cpc on the lighting circuit as mentioned in previous threads.

So is this a 17th edition board with two RCD's

Batty

 

[Apache]

Patch are you a real person or are you a computer search engine for threads on this site!! Ha Ha Everything on circuit was unplugged when ins testing.

This is also the house with no cpc on the lighting circuit as mentioned in previous threads.

Nah I'm real.

go post in my vet thread.................

 

[M107]

Only other thing I've had like this was random tripping for a day or so, everything unplugged & boiler off.

Found a JB under the groundfloor boards with a huge zapped slug across all conductors.

 

[Blue Fox]

No floorboards underneath as concrete floor and can't get above ceiling as tiled floor above - going to be a good one this!!

 

[Evans Electric]

Have you done the half test on the RCD ? Quite a few go wrong these days. We had a Crabtree , fitted by us, house rewired by us, started tripping after a few days. All appliances unplugged, ring tested out OK, just left with the boiler on a spur, disconnected that , still tripping. I swore at it , tapped it with a screwdriver, lightly and it tripped. It also tripped when people let the door slam nearby. So although tests were fine , the slightest vibration tripped it, fitted replacement , never heard from them again.

 

[green-hornet]

Have you done the half test on the RCD ? Quite a few go wrong these days. We had a Crabtree , fitted by us, house rewired by us, started tripping after a few days. All appliances unplugged, ring tested out OK, just left with the boiler on a spur, disconnected that , still tripping. I swore at it , tapped it with a screwdriver, lightly and it tripped. It also tripped when people let the door slam nearby. So although tests were fine , the slightest vibration tripped it, fitted replacement , never heard from them again.

I have had this problem before with similar outcomes.

I think to keep prices down some of the usual quality control is passed onto the electricians fitting the devise, cheaper to replace the occasional faulty unit than to factory test each unit.

 

[Andy™]

I have had this problem before with similar outcomes.I think to keep prices down some of the usual quality control is passed onto the electricians fitting the devise, cheaper to replace the occasional faulty unit than to factory test each unit.

If anyone can get inside info to prove this, maybe we should start to charge RCD manufacturer a few hours labour for testing RCD, removing RCD, going for replacement and re-fitting new RCD. and maybe a standard rate of

 

[Blue Fox]

Because its a dual rcd board I swapped the rcd's round thinking that it could be a faulty rcd but the same circuits are causing the rcd to trip. I would think it unlickely that I've got 2 faulty rcd's. Going round there tomorrow to try and sort the problem for them.

 

[Andy™]

having read all the thread.... the fault may be a neutral in the wrong place - had similar problems a while back when i changed a CU. few radials with 1 socket (used to be storage heaters) - somehow got a neutral from one on other side, cant remember what was plugged in now, but when something on a different circuit was turned on, it tripped RCD

Or it could be a borrowed neutral on lighting circuit. possibly between lighting circuit and socket (wall lights normally)

 

[green-hornet]

I would concur with andy on this one, a swapped nuetral would give the faults you are getting.

Its a long job but disconnect all nuetral leads and try to id a rougue circuit, main culprits are the lighting circuit, this being the most open to diy abuse.

You know the scene, they buy a light fitting, connect all the black cables together and all the reds, or swap a nuetral for a switch, sorry its blue and brown now but you know what I mean.

 

[Blue Fox]

Hello Guys,

All sorted now. Thanks for all the help. found 2 faults in the end. Cooker causing rcd to trip and the kitchen ring. After taking all the sockets off, unable to clear fault, but customer had a new kitchen fitted a couple of years ago and all kitchen was wired in new cable but cables leaving c/u were in older cable. Eventually after taking several kitchen cupboards apart found an original socket near the floor where the "electrician" had connected in the cable for the new sockets. Found cables falling out of this and touching between nutral and earth. Not sure why my ins test didn't find it originally but did today?? Same meter and everything. Thing was with this socket its chased into the wall originally, but instead of chasing the new cable into the wall whoever did it has just run the cable straight out of the top of the socket and screwed the face back on as far is it will go!! On top of this it is directly below a plastic push fit sewage pipe from the washing machine. Didn't have anything to sort it with on the van today so going to move it up the wall a bit and fit a surface mount box with a joint in there as it can't be used as a socket.