Nightmare of a day. RCD tripiing under any load

[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.