Nightmare of a day. RCD tripiing under any load

[brizospark]

Have had one of them days. I had a board change to do and a few other bits and bobs so everything was going great until I tried to put power back on.

Basically I have replaced a 3036 board with a split load Wylex board. One half of the board is working fine but the other half's RCD is tripping as soon as anything is plugged into it.

If I remove all plugs from sockets then the RCD holds but as soon as I plug anything in, kettle, sky box, TV, it trips instantly. On this side of the board is the cooker, 1 x lighting circuit and 2 x ring mains, funny enough the RCD isn't tripping when the lighting circuit or cooker is on.

Now I have checked that I have neutrals from correct circuits going to the correct neutral bar, several times and these are OK. I tried replacing the RCD itself with the one that was OK and it still tripped. What else is strange is that the kitchen ring is on the side of the board which is fine but if I plug anything into a kitchen socket the RCD which isnt even protecting this is tripping!! I opened up sockets and everything looked OK but it was getting late on so I replaced the offending RCD with a main switch I had in van just so the couple have power on tonight before I go back again tomorrow. Switched on with RCD removed and everything fine.

Anyone had experience with this problem before? Any advice much appreciated

 

[Dubbo]

Have had one of them days. I had a board change to do and a few other bits and bobs so everything was going great until I tried to put power back on.

Basically I have replaced a 3036 board with a split load Wylex board. One half of the board is working fine but the other half's RCD is tripping as soon as anything is plugged into it.

If I remove all plugs from sockets then the RCD holds but as soon as I plug anything in, kettle, sky box, TV, it trips instantly. On this side of the board is the cooker, 1 x lighting circuit and 2 x ring mains, funny enough the RCD isn't tripping when the lighting circuit or cooker is on.

Now I have checked that I have neutrals from correct circuits going to the correct neutral bar, several times and these are OK. I tried replacing the RCD itself with the one that was OK and it still tripped. What else is strange is that the kitchen ring is on the side of the board which is fine but if I plug anything into a kitchen socket the RCD which isnt even protecting this is tripping!! I opened up sockets and everything looked OK but it was getting late on so I replaced the offending RCD with a main switch I had in van just so the couple have power on tonight before I go back again tomorrow. Switched on with RCD removed and everything fine.

Anyone had experience with this problem before? Any advice much appreciated

Have you checked that the neutrals to the RCD and neutral bars are in the correct place not just the circuits?

 

[Paultrim123321]

If your replacing a CU then how can you not test prior to the replacement? How do you know that any faults you find after the new CU is installed we're not generated due to the installer? I am also presuming and hoping that you test after the replacement too?

 

[trev]

I am also presuming and hoping that you test after the replacement too?

No guarantee of that though is there.

 

[Paultrim123321]

No but you would hope so. A lot is said, not just on this forum but in generally in the electrical industry about 'wet pants', house badgers, Electrical Trainee and their lack of regard for any testing etc but then there are electricians who will happily replace a CU without thorough testing of their work.

 

[trev]

No but you would hope so. A lot is said, not just on this forum but in generally in the electrical industry about 'wet pants', house badgers, Electrical Trainee and their lack of regard for any testing etc but then there are electricians who will happily replace a CU without thorough testing of their work.

Don't know how they sleep at night, I know I wouldn't.
That said, I've been on projects where lads have been quite honest about making up test results because "You know it's right", on one of them one guy made up the first test sheet and then photocopied it rewire after rewire and got away with it for weeks because of lax management. Projects that I've ran, that was stamped out very quickly.

 

[Sharpend]

The problem I find is this behaviour is common within large Niceic firms as the tester believes that any problems further down the line will not effect them and will be dealt with by the company! Not so its the one who signs who is responsible. The company will not give an iota other than keeping their reputation intact.

 

[richy3333]

No but you would hope so. A lot is said, not just on this forum but in generally in the electrical industry about 'wet pants', house badgers, Electrical Trainee and their lack of regard for any testing etc but then there are electricians who will happily replace a CU without thorough testing of their work.

Is it just me that has a smutty wandering mind?

 

[Rampantchilli]

Have you checked that the neutrals to the RCD and neutral bars are in the correct place not just the circuits?

id say your on the money here, but it could be a ring accidentally placed across 2 rcds, would certainly make sense

 

[LED Lighting]

Excuse if already sorted - only read 1st 3 pages!
The problem is clear Neutral Earth Fault! - it would only trip under load as there is no current to leak when nothing is plugged in.
IR between N&E on each circuit
Slit Circuit half way and test each half
Keep splitting effected circuit in half till you find the fault between 2 points and theirs your problem!

Its not a borrowed neutral as only 1 RCD is tripping under load - both would!

This is why you should ALWAYS IR Test all the circuits before even removing any wire out of the old CU!
Classic egg on face

 

[brizospark]

Thanks to everyone for replies, first of all I have to agree with wirepuller on his quote that when running a business it is simply unrealistic to carry out testing before quoting a customer for a board change. So well done to you for your honesty. I do, however always carry out a visual check to see that the condition of the wiring is in suitable condition to re-terminate into a replacement consumer unit. There have been many occasions where I have politely declined to replace the consumer unit stating that an upgrade of the wiring would be required

Secondly I always provide certification post board change. On this occasion I had started the board change late on in the day and encountered this problem late on. I, of course, restored power to the property temporarily and then first thing in the morning revisited property where, thanks to some of the more helpful comments, I managed to quickly trace the fault to a junction box below the floor which had a damaged cable resulting in a N - E fault. This was quickly rectified and the RCD reinstated, installation tested with satisfactory results.

By the way I would like to state that I am in no way a Electrical Trainee! I have been in the trade for a long time and have completed the 2391 and have been very involved with electrical inspection, testing and certification since. I merely posted a problem I was having with a view to receiving some feedback with some ideas of where the fault most likely would be. I must be under the illusion that this was the purpose of the forum. It did seen though that as soon as some criticism was raised a lot of other forum members jumped on the bandwagon, slating me, presuming I was a Electrical Trainee/cowboy that had to clue or inclination on testing. It does seem that some of the members revel in jumping on these situations as soon as the opportunity arises. To those members I do apologise that I am less gifted than yourselves!!

I wish I did have the time to carry out a full test before quoting for consumer unit replacement but the trade is on its knees as it is and to be asked to carry out a board change these days instead of customers getting the work done as a homer is a rare occurrence in these parts

 

[LED Lighting]

By the way I would like to state that I am in no way a Electrical Trainee! I have been in the trade for a long time and have completed the 2391 and have been very involved with electrical inspection, testing and certification since. I merely posted a problem I was having with a view to receiving some feedback with some ideas of where the fault most likely would be. I must be under the illusion that this was the purpose of the forum. It did seen though that as soon as some criticism was raised a lot of other forum members jumped on the bandwagon, slating me, presuming I was a Electrical Trainee/cowboy that had to clue or inclination on testing. It does seem that some of the members revel in jumping on these situations as soon as the opportunity arises. To those members I do apologise that I am less gifted than yourselves!!

You say your not a Electrical Trainee and have done 2391 so my question is what the hell are you doing energizing a replacement consumer unit when clearly you have not undertaken any testing! Sorry but clearly you should go back to college!

With regards to no time to test prior I always always book a 5 minuet slot in at the end of a day prior to starting the replacement CU usually on way home from a job to do 2 IR Tests!
1. IR - LE
2. IR - NE

This takes about 5 minuets to do and will never put you into this situation where you have a not tested CU which you have energized and "TRIP"

 

[brizospark]

You say your not a Electrical Trainee and have done 2391 so my question is what the hell are you doing energizing a replacement consumer unit when clearly you have not undertaken any testing! Sorry but clearly you should go back to college!

With regards to no time to test prior I always always book a 5 minuet slot in at the end of a day prior to starting the replacement CU usually on way home from a job to do 2 IR Tests!
1. IR - LE
2. IR - NE

This takes about 5 minuets to do and will never put you into this situation where you have a not tested CU which you have energized and "TRIP"

Ok so if you have a customer half an hour away you will travel there at the end of a day grafting to carry out a few tests then go there the next day? You obviously have more time than me. Well sorry mate but that's not for me and I can guarantee you 99% of sparks wouldn't do this either!

With regards to energising the board prior to testing. In a newly wired job I would not do this but because this was a straight replacement I will admit I do this and again so will the vast majority of other sparks.

So you are go to customers to do 2 x IR the night before well whats to say that the rest of the testing is going to be ok?

 

[oldtimer]

Thanks to everyone for replies, first of all I have to agree with wirepuller on his quote that when running a business it is simply unrealistic to carry out testing before quoting a customer for a board change. So well done to you for your honesty. I do, however always carry out a visual check to see that the condition of the wiring is in suitable condition to re-terminate into a replacement consumer unit. There have been many occasions where I have politely declined to replace the consumer unit stating that an upgrade of the wiring would be required


Secondly I always provide certification post board change. On this occasion I had started the board change late on in the day and encountered this problem late on. I, of course, restored power to the property temporarily and then first thing in the morning revisited property where, thanks to some of the more helpful comments, I managed to quickly trace the fault to a junction box below the floor which had a damaged cable resulting in a N - E fault. This was quickly rectified and the RCD reinstated, installation tested with satisfactory results.

By the way I would like to state that I am in no way a Electrical Trainee! I have been in the trade for a long time and have completed the 2391 and have been very involved with electrical inspection, testing and certification since. I merely posted a problem I was having with a view to receiving some feedback with some ideas of where the fault most likely would be. I must be under the illusion that this was the purpose of the forum. It did seen though that as soon as some criticism was raised a lot of other forum members jumped on the bandwagon, slating me, presuming I was a Electrical Trainee/cowboy that had to clue or inclination on testing. It does seem that some of the members revel in jumping on these situations as soon as the opportunity arises. To those members I do apologise that I am less gifted than yourselves!!

I wish I did have the time to carry out a full test before quoting for consumer unit replacement but the trade is on its knees as it is and to be asked to carry out a board change these days instead of customers getting the work done as a homer is a rare occurrence in these parts

What absolute TOSH whats wrong with doing a global IR check at least you can tell the customer there is a problem before you start. I always do but I don't pass on my initial reading ie they are for my own use as I have done it in my own time.

 

[Plonker 3]

Ok so if you have a customer half an hour away you will travel there at the end of a day grafting to carry out a few tests then go there the next day? You obviously have more time than me. Well sorry mate but that's not for me and I can guarantee you 99% of sparks wouldn't do this either!

So how the hell do you quote for work, find out if bonding is upto scratch, what size DB to take to the job?

 

[trev]

You're there anyway and talking to the customer, imho it gives a good impression to say I'm just going to carry out a couple of quick tests to make sure there's no latent defects. It also presents a professional image and gives you a heads up on anything waiting to bite you on the bottom.