RCD Tripping

[willy.d]

Help needed please!

RCD supplying three ring final circuits. Everything unpluged, turned off etc. Reset all MCB's and RCD. Then, on any of the circuits apply a load (different loads, kettle, tv etc) and the RCD trips?

This is an existing install working fine untill now. I'm thinking the RCD is defective?. Only had an hour there for a quick poke around and back tomorrow with my megger for a closer look but some pointers would be very welcome!

Thank you

 

[nickblake]

It could if a neutral to earth fault has developed , think about it you have 3 ring circuits everything un plugged , plug in an appliance on any of the 3 circuits and the RCD trips , so look at the common factor here neutral and earth , all the neutrals and earths are linked neutrals on their bar earth on their bar if you have a fault on any of those three circuits N to E then when the load is applied the fault is picked up via the neutral s and earths of all circuits ,
What is needed to be done is to disconnect each circuit from the board neutrals and lives then reset the RCD and try again till you eliminate the circuit that causing the problem or simply test the IR on each of the circuits L E NE LN , even doing a continuity test on these may pic up a fault , and do as the other guys have said if all is well check the RCD tripping time , ramp test , etc but i would place my hard earned cash on a NE fault on one of those circuits , as i have said test each circuit individually even if its removeing the Neutrals from each circuit till the RCD stops tripping then test the circuit thats causing the fault

 

[FatBob]

Thanks Nick, you are of course correct

 

[willy.d]

##Update##
Ok, so went back yesterday. First thing, I ramp tested the RCD, which tested fine (so no quick fix unfortunately). I then indeed found low IR between Neutral and earth on one of the three circuits.
Next, I dropped all the socket plates off the wall (client had recently replaced many with stainless flat plate sockets, and some were very 'busy' behind) though nothing obvious in terms of pinched cables etc found. I then re-tested and the fault had disappeared, sockets back on the wall one by one, MCB's & RCD reset, power back on, happy client. I would have been happier if I knew which one caused the fault though.....

Many thanks again for all your contributions, very much appreciated.

 

[nickblake]

Willy i bet you moved the fault you said you had a socket that was busy , what could have happend is the faceplate screw caught the neutral causing a short , simple fault ,and what would have happend is when you removed the faceplate it removed the fault when you put the face plate back it missed all the cables hence no more fault

 

[RogertheBodger]

Isn't Electric wonderful?

Good thread, good help, good result.

 

[Goody]

Useful thread, learned a few tricks. Thanks!

 

[Gazzdid]

Definatly agree with nickblake I'd put my last dollor on it. Glad to see you got to the bottom of it willy, like you said it would have been nice to have found the actual problem so you could have rectified it and been safe in the knowledge it's not going to rear it's ugly head again but I suppose alls well that ends well

 

[telectrix]

at least if the fault recurs, you know where to look. must have been a N/E fault behind 1 of the sockets. cable trapped, insulation nicked.

 

[mayfair]

Tel just reminded me of a job i done in a factory long long time ago, I explained to the production manager (Hitler type) that the insulation had been nicked.......................He had all the factory lined up saying he was gonna get to the bottom of who had knicked his insulation, to much stuff going missing etc ......He looked a right plonker.

at least if the fault recurs, you know where to look. must have been a N/E fault behind 1 of the sockets. cable trapped, insulation nicked.

 

[p11jor]

N-e fault sounds like to me.

 

[telectrix]

N-e fault sounds like to me.

come in number 7 , your time is up.

 

[p11jor]

Lol I don't see all the answers on here do I because I just follow the link from my emails on phone and it's that slow to go back pages!

 

[telectrix]

ah, someone who knows how to use a moby for other than phoning people... respect. i can just about master text thingies. (reading , not sending)

 

[p11jor]

You need to get yourself one of these apple phones.....plays music, has Internet, email, and there is a application were I can send invoices straight from the phone and they get it on a official letterhead, same for estimates and it keeps it all logged like a proper database system...all fits nicely into your pocket!

 

[Gazzdid]

You need to get yourself one of these apple phones.....plays music, has Internet, email, and there is a application were I can send invoices straight from the phone and they get it on a official letterhead, same for estimates and it keeps it all logged like a proper database system...all fits nicely into your pocket!

sounds a great app whats it called?