DIY Doctor UK DIY Forums

Earlier today, whilst the only electrical item plugged in was a kettle (not being used) and a new radio (switched on) - no fridge, no cooker, no lights on, nothing else - the stand alone RCD tripped, and will not reset.

The wiring configuration is as follows:

Meter. One pair tails to stand-alone RCD.

Two pairs of tails out from RCD, one pair to 6 way C.U. and the other pair to 1 way C.U. which is dedicated to the cooker radial circuit, protected by 32 amp MCB.

I disconnected the radio and kettle and opened up a socket at random. With with the RCD in the OFF position but the CU main switch on, the live terminal is still live. And so is the Neutral! This is also the case on the lighting circuit at the ceiling rose. This showed up with a neon screwdriver tester.

I then took the cover off the RCD. The feed live was (of course) live and the neutral was not live, but on the load side, with the two pairs of tails, it showed live on both live and neutral terminals.

Does anyone know where the fault might lie, and can anyone explain how sockets can still be live when the RCD, which protects the whole CU, has tripped?

Any advice would be gratefully received.

Heffs

Hi Heffs, first things first , how far can you throw that screwdriver?, ITS NOT FAR ENOUGH! try harder!!!
Sorry but they are dangerously misleading items which I would not have in my tool kit!
It is just possible the RCD has only broken the Neutral & not the Live.
if so then through any load connected you will'see' live on open ended Neutral
Going back to RCD, with both CU main switches 'OFF' does it reset, don't forget some don't go all the way down when they trip & must be pushed to bottom first b4 they will go up to 'ON' position.
If now 'ON' try each main sw. in turn.... you obviously know enough logic to take it from here!!! good luck & please let us know outcome REGARDS SPARX

[quote="heffs"]Earlier today, whilst the only electrical item plugged in was a kettle (not being used) and a new radio (switched on) - no fridge, no cooker, no lights on, nothing else - the stand alone RCD tripped, and will not reset.

The wiring configuration is as follows:

Meter. One pair tails to stand-alone RCD.

Two pairs of tails out from RCD, one pair to 6 way C.U. and the other pair to 1 way C.U. which is dedicated to the cooker radial circuit, protected by 32 amp MCB.

I disconnected the radio and kettle and opened up a socket at random. With with the RCD in the OFF position but the CU main switch on, the live terminal is still live. And so is the Neutral! This is also the case on the lighting circuit at the ceiling rose. This showed up with a neon screwdriver tester.

I then took the cover off the RCD. The feed live was (of course) live and the neutral was not live, but on the load side, with the two pairs of tails, it showed live on both live and neutral terminals.

Does anyone know where the fault might lie, and can anyone explain how sockets can still be live when the RCD, which protects the whole CU, has tripped?

Any advice would be gratefully received.

Heffs[/quote]

heffs
if you have live on feed and load side with rcd switch showing off
then , u could have a faulty rcd.
the possibility of this rcd being in your supply , serving a tt system where you could have an earth rod is important.
i think u need to get in an electrician immeadiately to check this out.
it may be this rcd is paramount for earth fault protection , as your

disconnection times can t be met

BLAKEY1963

Thanks, both Sparx and Blakey.

I found the answer. Disconnecting each neutral in turn at the CU, I found which circuit was faulty and traced it back from there.

Even though I was working no where near a socket, whoever wired up the house put in a long (3m) diagonal spur cable into which I put a masonry nail. Once I'd isolated the cable I was able to reset the RCD and on flicking the Test switch it operated fine.

By the way, the house does not have an earth rod, so not, I think, a TT system.

Sorry I haven't replied before, but only went back to the property yesterday.

Once again, thanks.

Heffs