Strange RCD Fault

[Guest569]

80amp main switch RCD, occasionally trips when a couple of circuits are switched on (doesn't matter which circuits) with nothing plugged in.

IR tests all good. Replaced RCD for new. Happens in all weather ( don't think its external )

Only sockets on this consumer unit.

Ive had my guys out at it twice with no joy. New build wiring from 16th edition.

Im going to investigate myself this week, Im sure Ive had loose connections causing tripping before, it about all I can think of, a loose tail somewhere around the main switch.


Anything else to look out for ?

Im pretty certain its not a dodgy nail at floorboard etc its fairly new property and in good condition with chipboard throughout.

 

[Guest569]

i'd be careful with a 1000V test. always the possibility of something left connected that you may not have seen, like aerial amp in loft.

just a thought..... if, as you say, the property is empty, is there a possibility of damp?

Yeah plenty of gadgets in the property which worries me but Im running out of options.

Its a new build I don't think damp is an issue but again that would show at 250v I would have thought. Only other thing I can think is boys have not tested properly...

The other day I was passing by so I popped in for an hour hence no test gear, So I have not had a good few hours at it myself with the gear...back friday though and I WILL find it !

 

[Octopus]

If the property is empty, how do you know when its tripping?

EDIT: Rip out the upfront RCD on the "sockets board" and fit RCBO's

 

[baldsparkies]

You say (Its also got 6 showers, around 10 bedrooms , 3 lounges, 2 dining rooms, 2 kitchens etc etc ...and around 25 circuits in total.)

Ok so how many of the above are on this poor little 30ma RCD !!!

If problems are occurring with the property empty, whats going to happen when they really get going.

With that many circuits I would consider RCBO's and get rid of any discrimination and/or nuisance tripping.

Have you tried disconnecting all circuits at the board making sure there open (no load) join all neutrals and earths together and chucking 1000v IR down em.
Try the same for earth to live (RCD probably to quick for an overload fault to take out the MCB)
And also is there a combi boiler, or something on a timer thats kicking in.
If the Earth Nuetrals are crossed it wont trip until a load resistance comes into play.
So a polarity check on all circuits could also pay off here.
See what that turns up for starters.
If its an empty building, you have a good starting point for finding this one.

 

[hasel5]

In fairness they were concerned that everything was not unplugged ...didnt tell me tat yesterday though !

So what was plugged in then as you say the property is empty?

 

[Megavolt]

Rcbo's for me. ge aren't to heavily priced.

This would be after I clamped it with no result.

Labour costs soon add up with faults like this. Rcbo's maybe cheaper overall and better job in end

 

[MDJ]

Disconnect all cables supplying sockets from Distribution Board and ensure you go around the whole premises unplugging everything, if any fused switch spurs are evident on the circuits and double pole make sure they are also switched off. firstly whack 500 volts across the browns, then the blues then the green and yellows, Then do it again with 1000 volts down all cores. Then test between browns and blues then brown and green and yellows, Then test between blue and green and yellows, then do the same with the meter to the ohms scale then connect one green and yellow from one cable with a brown from the other and the same again, This is the basic test to confirm continuity to confirm actual essential readings and indeed polarity and once that has been done you may have an idea regarding any issues on the circuit. If everything is good then do the RCD test, X half then X1 then X5 on both poles at 0 degrees and then 180 degrees, at times half the RCD should not trip, at times 1 you want it to trip under 200ms and 300ms for other types of unit, check BS number and at time 5 under 40 ms. Check table 61 page 191 of the BGB for IR minimum values and double check your test kit is working on a proven unit.

 

[hasel5]

my moneys on A N-E fault

 

[baldsparkies]

Depending on level of competence this is a domestic dwelling that's empty.
You might not be able to rectify the fault on a first visit but you should find the darn thing.
With a decent set of testers isolate the fault from appliance fault, or install fault. If its install, narrow your fault to a circuit or circuits or circuit component ie rcd itself.
If its appliance find that.
If its a build up due to too many circuits on the one Rcd go the RCBO route.
But for heavens sake, get a competent electrician to look at it before the customer has to go for a second mortgage.
Flipping a coin and calling heads or tails wont cure the problem.

 

[dazza1981]

Depending on level of competence this is a domestic dwelling that's empty.
You might not be able to rectify the fault on a first visit but you should find the darn thing.
With a decent set of testers isolate the fault from appliance fault, or install fault. If its install, narrow your fault to a circuit or circuits or circuit component ie rcd itself.
If its appliance find that.
If its a build up due to too many circuits on the one Rcd go the RCBO route.
But for heavens sake, get a competent electrician to look at it before the customer has to go for a second mortgage.
Flipping a coin and calling heads or tails wont cure the problem.

Yeah but apparently fault finding is different up there!!!

 

[Octopus]

Depending on level of competence this is a domestic dwelling that's empty.
You might not be able to rectify the fault on a first visit but you should find the darn thing.
With a decent set of testers isolate the fault from appliance fault, or install fault. If its install, narrow your fault to a circuit or circuits or circuit component ie rcd itself.
If its appliance find that.
If its a build up due to too many circuits on the one Rcd go the RCBO route.
But for heavens sake, get a competent electrician to look at it before the customer has to go for a second mortgage.
Flipping a coin and calling heads or tails wont cure the problem.

Can't wait to see JRC's reply to this! lol

 

[baldsparkies]

Can't wait to see JRC's reply to this! lol

Well for heavens sake, the blokes here are thinking it, somebody has to say it.
A good sparky would have found this. The fact the boss as to cover like this wont leave customers feeling very confident.
We are all different granted, but intermittent fault or not its a fault and I would not leave until I had an answer for it at very least.
I'm simply saying its not going to look good for the bloke going backwards and forwards.

 

[micknew]

Can't believe the OP could get into so much trouble in locating an earth leakage problem.

 

[Octopus]

Well for heavens sake, the blokes here are thinking it, somebody has to say it.
A good sparky would have found this. The fact the boss as to cover like this wont leave customers feeling very confident.
We are all different granted, but intermittent fault or not its a fault and I would not leave until I had an answer for it at very least.
I'm simply saying its not going to look good for the bloke going backwards and forwards.

I agree 110% but the OP hasn't got a good track record when it comes to taking "criticism"

 

[dazza1981]

Well for heavens sake, the blokes here are thinking it, somebody has to say it.
A good sparky would have found this. The fact the boss as to cover like this wont leave customers feeling very confident.
We are all different granted, but intermittent fault or not its a fault and I would not leave until I had an answer for it at very least.
I'm simply saying its not going to look good for the bloke going backwards and forwards.

I said this in post 21 mate.... but got shot down in flames for it by the op.
I blame the BOYS!!!!

 

[Guest569]

Can't believe the OP could get into so much trouble in locating an earth leakage problem.

Jesus this forum is a joke.

Im more than experienced in domestic fault finding than most on here. Dealing with "council spec" rewires for over 10 years Ive seen it all.


If anyones actually cares to read my initial posts, we have been through the basic procedures and this is not a simple fault. Its guaranteed something bizarre....

Perhaps wind blowing a wet leafy tree on to a dodgy connection somewhere outside ? Just one example that could not be found by any procedure listed so far by the experts ...

Bizarre faults do happen, and I'm certain this one is a strange one ...hence title.

This forum is pretty pathetic, everyone far to quick to assume the OP hasn't got a clue !

 

[Plonker 3]

If you have wet leafs blowing against connections, then that is surely instant dismissal leaving a connection exposed like that?

 

[Guest569]

Simple fault....lol. Plenty would be scratching there head at this one.

Just to clarify...I had a spark and a labourer at the job for 3 hours. I popped in for 1 hour with no test gear to check the obvious....I go back friday and armed with the correct gear I WILL find it..

This is all assuming my guys have done the procedures as they should have ....kinda hoping they have not

The customer has complete trust in me, so please concentrate on your own customer relations !

 

[Meggerman]

Have you done 250V I/R L&N-E with everything plugged in and switched on.

 

[dazza1981]

Have you tried a earth fault wet leaf impedance test!!!!

 

[Guest569]

If you have wet leafs blowing against connections, then that is surely instant dismissal leaving a connection exposed like that?

another great assumption.....its not our install.

 

[Plonker 3]

I never said it was.

 

[Guest569]

I never said it was.

So wtf are you talking about instant dismissal for ?

 

[Meggerman]

So wtf are you talking about instant dismissal for ?

**** answering that, answer my question

 

[Plonker 3]

Because it would be surely wouldn't it?

what you getting so defensive about it for? Was it really you who did it?

 

[jaypp]

there could be more than 1 fault. eg continuity (ring) + n-e fault (but not 'dead short'), hence 'boys' missed it. be good to know findings JRC

 

[Guest569]

So...The wet leaf thing ....Would any procedures by the experts show this ?


Exactly. Far to many variables to solve over the internet....

I appreciate the advice but don't appreciate posts that assume I know nothing !

Typical of this forum though.

 

[DPG]

Jesus this forum is a joke.

Im more than experienced in domestic fault finding than most on here. Dealing with "council spec" rewires for over 10 years Ive seen it all.


If anyones actually cares to read my initial posts, we have been through the basic procedures and this is not a simple fault. Its guaranteed something bizarre....

Perhaps wind blowing a wet leafy tree on to a dodgy connection somewhere outside ? Just one example that could not be found by any procedure listed so far by the experts ...

Bizarre faults do happen, and I'm certain this one is a strange one ...hence title.

This forum is pretty pathetic, everyone far to quick to assume the OP hasn't got a clue !

You seem to have seen it all and know it all - so go fix it then. Daz

- - - Updated - - -

So...The wet leaf thing ....Would any procedures by the experts show this ?


Exactly. Far to many variables to solve over the internet....

I appreciate the advice but don't appreciate posts that assume I know nothing !

Typical of this forum though.

You keep moaning about this forum, but you keep coming back. Daz

 

[Guest569]

Because it would be surely wouldn't it?

what you getting so defensive about it for? Was it really you who did it?

Cause I find you a bit of a ----- to be honest. You have nothing constructive to say, only attempted digs so jog on.

 

[Plonker 3]

You seem to have seen it all and know it all - so go fix it then. Daz

He did go to fix it but couldn't.

 

[Guest569]

**** answering that, answer my question

L/N-E with everything plugged in is something I have not tried actually thanks !