Rcd nightmare

[guest119]

Yes Tony, twice its half, same as a piece of string?

 

[SJD]

definitely a N fault. possibly a N-E reversal in back of a socket.

Just to add, the fault might not be in a socket, could also be on another circuit on the RCD.

 

[Hawk81]

Why fit a dual board and only use one side of it? Why not just fit a 5 way board if you were happy with one RCD on every circuit. On a small installation like that I would have fitted 5 RCBOs. Any electrician worth his salt should be able to find that fault. Sounds very like a neutral fault.

 

[Engineer54]

The mind just boggles at some of these thead help queries. This has just got to be one of our fast track wannabe friends... Doesn't even know the reasoning behind the 2 X RCD CU concept!!

 

[tommyh]

I cant believe that people have actually given serious replies to this.

OP if this is a serious question I suggest you sell your tool (and any test equipment if you own any).

Then find a reputable electrician who you will pay to put right your bodge job and explain to your customer you are not actually competent to do what they paid you to do.

Thanks for for all you help

 

[Octopus]

Oh dear, the OP's been on this morning, viewed the thread and not updated us.

My crystal ball sees an unhappy client and a puzzled "electrician"

 

[Darkwood]

We get many threads saying how we are sometimes a little bit too tough on people on here ... well this is just one of those threads where it is justified IMHO...

Why fit a duel RCD board and only utilise 1 rcd - (Doubles the chance of total power loss in any fault)?
As the rcd is monitoring multiple circuits why is the OP only testing one of them ( surely swapping the circuits across to the other RCD one at a time to identify the offending circuit isn't rocket science )?
Why do I get the impression the OP does not understand fully how RCD's work (he has made an assumption too quickly this is socket related without thinking about the problem ) ?



To the OP - If you have a crushed / trapped wire between too circuits this is IMHO the only time I expect to see a fully qualified Electrician on here confused by such a situation, this can manifest into rcd tripping even when non rcd circuits are loaded up and is a very difficult set-up to understand for any that haven't encountered such a fault before, lets assume this is not the case, just remove the circuits in full from the board test all circuits, even test between circuits in this case. Add the socket circuit and then try load it up without other circuits connected (including disconnected N/E), if it doesn't trip then add a circuit 1 at a time until your fault occurs - once you Identify the circuit that was added when the fault returned then concentrate on that and the socket circuit as maybe having a fault together.

Alternatively as mentioned a reversed polarity set or high impedance N/E on the socket circuit may be present at a point / outlet you have failed to find - this could be a spur on top of units or ignition point for a gas hob etc etc... often missed outlets.

Lastly - learn your trade and specifcally the fundementals of both single and double pole rcd operation and why fitting a duel board and throwing all the circuits on one rcd would be considered poor practice when the option of 2 rcd's is present.... this is basic stuff TBH!

 

[Plonker 3]

I think only one RCD was used as they have a shared neutral and it was the easiest way to stop it tripping.

 

[HandySparks]

Why fit a duel RCD board and only utilise 1 rcd - (Doubles the chance of total power loss in any fault)?

Eh?

Surely the chance of total power loss on a single earth fault changes from zero (with two RCDs) to 100% (with all circuits on one)!

 

[Darkwood]

Eh?

Surely the chance of total power loss on a single earth fault changes from zero (with two RCDs) to 100% (with all circuits on one)!

You missed my meaning ... if your circuits are balanced over 2 rcd's then an earth fault would only lose you 50% circuits where as the OP's set up would lose everything but you cannot say zero either as faults between circuits across differing rcd's would take 100% power out as would borowed Neutrals in some cases.... do get what you mean and double was a plucked out value just to get across my point maybe 30% be more accurate as its subject to the arrangement of the circuits.

 

[snowhead]

Anyone know what the value of OK is?

It's about right.
It'll do
Not far out.
Could be better.
Seen worse


But in reference to a Technical subject,, Worthless.

 

[tommyh]

Hi I have already narrowed down the fault to the ring circuit, with the ring circuit disconnected, the RCD holds in and the RCD test button works, I have tried the faulty circuit on the other RCD and the fault returns... RCD won't hold in with any sort of load on it, I have done an insulation resistance test showing <200M ohms between each, I have also done an end to end, r1 + r2 test, r1 + rn test, all good, I have been in every socket/spur and can't see any crossed wires. The test results does not show that anything is wrong. Surely if there is a trapped wire the insulation resistance test would indicate a fault or if there has been a crossed wire the my (r1 + rn) or r1 + r2 would indicate I have a problem????

 

[Plonker 3]

Does the fault have a certain pattern to when it is happening? ie certain times of the day, when certain appliances are plugged in etc?

 

[tommyh]

Soon as there is any sort of load the RCD trips, 2/3 appliances anything at all.

 

[plugsandsparks]

Never mind the socket cct, I would treat the whole installation as suspect and start again, cct by cct.