Tripping RCD on new Ring Main

[Electron]

I have installed a new ring main in a kitchen extension and tested for continuity and insulation resistance before connecting to Consumer Unit. As soon as main switch turned on, even with all the MCB's switched off, the RCD tripped. I removed all the connections to the consumer unit from the new ring and the rest of the circuits were fine. So problem is with the new ring main but I can't think what the problem is. Has anyone any advice?

 

[Pete999]

I have installed a new ring main in a kitchen extension and tested for continuity and insulation resistance before connecting to Consumer Unit. As soon as main switch turned on, even with all the MCB's switched off, the RCD tripped. I removed all the connections to the consumer unit from the new ring and the rest of the circuits were fine. So problem is with the new ring main but I can't think what the problem is. Has anyone any advice?

Anything plugged in or connected via a fused spur?

 

[westward10]

Did you check polarity as one of your dead tests.

 

[Pete999]

I have installed a new ring main in a kitchen extension and tested for continuity and insulation resistance before connecting to Consumer Unit. As soon as main switch turned on, even with all the MCB's switched off, the RCD tripped. I removed all the connections to the consumer unit from the new ring and the rest of the circuits were fine. So problem is with the new ring main but I can't think what the problem is. Has anyone any advice?

Ring Final Circuit Simon not a ring main

 

[Octopus]

What do you plan to do next?

Tell us and we'll give you some pointers......

 

[westward10]

I am thinking cpcs and neutrals incorrect terminals at an accessory.

 

[The Ghost]

Maybe mixed up neutrals? On dual RCD possibly? Did you do R1 R2 that maybe would throw up a fault. Just stabs in the dark there.

 

[buzzlightyear]

What do you plan to do next?

Tell us and we'll give you some pointers..

yeah what, show him how put a ring in and test.

 

[buzzlightyear]

possible he has put the neutrals on wrong side of the board non rcd side.

 

[Dannyg8810]

Maybe damage to cable from installation?

 

[telectrix]

on my patch.can come and sort for a reasonable fee.

 

[buzzlightyear]

now, I bet he's biting his lips now tele. that you are luring like a shark in that area.

 

[KEV 1 N]

I'll tell you what.....you have to be thick skinned to come on here asking for advice!

 

[buzzlightyear]

I'll tell you what.....you have to be thick skinned to come on here asking for advice!

yeah, like a rhino.

 

[Octopus]

yeah, like a rhino.

And be a rhino that answers questions too. ....

 

[buzzlightyear]

delete

 

[buzzlightyear]

delete

 

[PEG]

I would say if the cables are giving the correct resistance readings,both as individuals,and in relation to each other,then what is left,is them being connected,in the wrong order...

Like Eric Morecambe...but with a MFT

 

[Midwest]

As its morning now, and there's no drunken debauchee going on, did you do all the dead tests in order Simon, like the teetotallers suggested?

 

[Taylortwocities]

possible he has put the neutrals on wrong side of the board non rcd side.

That's my bet too.

 

[buzzlightyear]

sorry Midwest ,I don't think he will tell us if he has solved the problem. I bet is head in bits after reading .what we have put on this post.

 

[Pete999]

Ring Final Circuit Simon not a ring main

Emmalaur, it may be an old reply, but if you can't get the basics right, what chance have you got?

 

[Pete999]

Emmalaur, it may be an old reply, but if you can't get the basics right, what chance have you got?

 

[Midwest]

sorry Midwest ,I don't think he will tell us if he has solved the problem. I bet is head in bits after reading .what we have put on this post.

I know we all like some banter, and OP has been brave enough to ask his question, but the forum is about answering questions. Lets hope OP comes back, so we can assist. This forum is populated with some who think they know it all (present company accepted), but they are just fooling themselves.

DIY'ers come on here asking some down right stupid questions, and some members fall over themselves to answer them. Can we not help fellow sparks. Just saying

 

[buzzlightyear]

I total agree what you saying. we band of brother spent yours of training.
go on courses to up date are knowledge. Mr DIY came on hear hoping that we will help them . not me .and the diyers are putting themselves in danger . plus costing us in monies .what they say is much knowledge is dangerous.

 

[HandySparks]

Was the cpc connected to the earthing bar in the CU when you did the IR testing?

 

[Lucien Nunes]

Indeed. If it was not connected, and the N of the circuit is faulted to real earth e.g. a pipe, you might have an N-E fault when the circuit is connected up that does not show on an IR test between the N & CPC alone, if the CPC is otherwise insulated from earth.

 

[elsparko]

fault finding is part of the apprenticeship, if you cant do that dont attempt electrical jobs would be my answer.

theres nothing difficult about ring circuits.

if you dont have a tester then best bet would be to disconnect all points on circuit and make sure everything is terminated correctly, failing that i doubt anyone is going to explain fault finding, it is what keeps us in a job.

 

[Taylortwocities]

Well. I suppose this is supposed to be an Electrician 's forum.

Would you be more understanding, if he had posted in the DIY section?

 

[elsparko]

no, diyers should not attempt electrical work.

 

[Octopus]

Shame the OP didn't update the thread when he dropped in last night .............

 

[elsparko]

Shame the OP didn't update the thread when he dropped in last night .............

maybe he has shorted out the live/neutral whilst live, using his fingers as a probe tester?

 

[Pete999]

maybe he has shorted out the live/neutral whilst live, using his fingers as a probe tester?

Naaaaaaa

 

[elsparko]

saying that, not all apprenticeships are equal, i was working as a sparks mate earlier this year, guy on double my wages was coming to me every 20 mins to see what to do, didnt mind helping him out as he was a road lighting sparky, only as good as what youve been taught,i should refrain from coming onto forums over weekend lol, im too mean.

 

[Electron]

Anything plugged in or connected via a fused spur?

No. Both fused spurs (Saniflow and toilet floor heating) switched off.

 

[elsparko]

disconnect the cables at the DB and shove them into the wallspace, theres nothing else that can be done sorry.

 

[Des 56]

No. Both fused spurs (Saniflow and toilet floor heating) switched off.

Are they double pole?

 

[buzzlightyear]

I have installed a new ring main in a kitchen extension and tested for continuity and insulation resistance before connecting to Consumer Unit. As soon as main switch turned on, even with all the MCB's switched off, the RCD tripped. I removed all the connections to the consumer unit from the new ring and the rest of the circuits were fine

No. Both fused spurs (Saniflow and toilet floor heating) switched off.

am I missing some thing or you!

 

[Electron]

What do you plan to do next?

Tell us and we'll give you some pointers......

I have retested the circuit. The results for continuity are r1 0.70 Ohms, rn0.7 Ohms and r2 1.13Ohms. So far so good!
r1 + r2 sockets 0.52-0.56 Ohms. I was expecting 0.46 Ohms, so a bit high.
r1+rn are all over the place. from 0.44 up to 0.86. No pattern. Should be 0.35.
The insulation resistance are Line to Neutral ˃500 M Ohms Line to CPC ˃500 M Ohms. Sadly, the Neutral to CPC was 0.
There are only ten sockets on the ring and two fused isolators.
Can anyone suggest what is causing the problem?

 

[Octopus]

Cable damage...

Time to split the ring to narrow down where the fault is