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.

 

[Sparkie30]

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"

so you telling me you learnt everything in college? i think i know the answer to that mate

 

[LED Lighting]

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 it was a straight replacement I will admit I do this and again so will the vast majority of other sparks

What a load of HOT AIR!

Yes I have had some CU Changes some 3 hours away and every time if its not practical I always IR before undoing anything!
You dont need to unplug anything anything as at the end of the day your only "PAT Testing" the appliances and installation all at the same time!

This is an added bonus because if an appliance has a fault then you can quickly identify this before starting.
I did this the other week - Dead short NE and <1Mohm LN and LE. Advised them it needed fault finding at rate which they agreed to - spent 4 hours and over 50% of cables where shot! went from CU Change to rewire like that!

 

[LED Lighting]

so you telling me you learnt everything in college? i think i know the answer to that mate

Not at all - just clear basics - dont energize circuit unless you tested it!
Common Sense sorry

To brizospark

Forget the IRs for a minuet as that will be picked up with the RCD, but what about no continuity on conductors and you have protected 2.5mm broken ring with a 32A!

Sorry cowboy springs to mind - and considering you need to issue a certificate how do you get these results? Disconnect everything again to retest it? Or make up the results?

 

[Paultrim123321]

If people are suggesting they have been asked to come in and replace the CU...who is making that decision? The client?
If someone rings me and asks to have a CU replaced I would want to know why they think it needs changing?

As the inspector that is up to me.

If a CU needs replacing there's every chance the wiring will need attention, therefore surely testing has to be carried out?

 

[Guitarist]

What a load of HOT AIR!

Yes I have had some CU Changes some 3 hours away and every time if its not practical I always IR before undoing anything!
You dont need to unplug anything anything as at the end of the day your only "PAT Testing" the appliances and installation all at the same time!

This is an added bonus because if an appliance has a fault then you can quickly identify this before starting.
I did this the other week - Dead short NE and <1Mohm LN and LE. Advised them it needed fault finding at rate which they agreed to - spent 4 hours and over 50% of cables where shot! went from CU Change to rewire like that!

No wonder the local sparks are complaining!

 

[moospark]

3 Hours away? Hadaway! I could be in Wales by then.

 

[sima24]

I never test when quoting. I provide a quote for board and explain in simple terms that any faults that are found (if any) will be charged accordingly. Also i agree with some posts that this situation seems very simple, no disrespect to poster but i would have known this fault as a 1st / 2nd year apprentice. Qualifications are one thing but nothing without the experiance.

 

[moospark]

And what does "every time if it's not practical I always I.R" mean?

 

[sima24]

Fault in my view is simply 1) borrowed neutral or 2) n-e fault (which would of been found on dead tests). Simples

 

[growler]

have you checked that the neutrals from the rcds and main switch are in the correct neutral bars ? this caught me out before !

 

[Guitarist]

So you guys who don't bother testing are happy to give the customer a surprise when the bill doubles at the end of the job?

 

[trev]

3 Hours away? Hadaway! I could be in Wales by then.

Gadgies waalkin tho marra, nee van lyk

 

[brizospark]

So LED you say you do this for board change three hours away. So you are telling me after a day working you will drive a six hour round trip to do two IR Tests then go back next morning ? WTF? Are you for real? How much are you charging because the fuel cost alone would be ridiculous

 

[moospark]

Gadgies waalkin tho marra, nee van lyk

Nah, He'll ride his sheep. All the way.

 

[wersolaruk]

Some proper tools on here like! Give the guy some slack! Everybody needs help once in a while.

 

[brizospark]

Nice one solar my thoughts exactly.

 

[brizospark]

Solar is right enough what's the point in having this forum if you can't ask!! What do these guys want to just talk about how great they are and how they know absolutely everything!!

 

[Plonker 3]

No it is for electricians to help each other. Not for people who are lazy to carry out work and expect the interweb to help them when the brown stuff hits the fan.

Just out of curiosity will you carry out a global IR on the next DB change that you have to do?

 

[sima24]

So you guys who don't bother testing are happy to give the customer a surprise when the bill doubles at the end of the job?

Yes. Customer is told before that if any problems / faults found they will be charged at £40 ph. This is verbal when quoting and written on quote in black and white. Im not testing on a quote, as far as im concerned if i pick up my tester then im working, and unless the customer would like to pay for a test before then im not doing it.

 

[sima24]

Each to their own but as long as the customer is made aware before I see nothing wrong with it.

 

[brizospark]

No it is for electricians to help each other. Not for people who are lazy to carry out work and expect the interweb to help them when the brown stuff hits the fan.

Just out of curiosity will you carry out a global IR on the next DB change that you have to do?

So was that not the case with this post you tw@?

 

[Plonker 3]

So you are happy to get a reptation for someone who looks for extra work after the event rather than taking a extra half an hour carrying out a bit of work and pass on your findings to the customer before hand?

You dont have to tell them what you have found, just that there will be remedial work required due to your test results.

 

[Plonker 3]

So was that not the case with this post you tw@?

Swearing makes you look like the kind of person who got the response he deserves on this thread.

 

[sima24]

BRizospark did you get to the bottom of the fault in the end?

 

[Marvo]

Yes. Customer is told before that if any problems / faults found they will be charged at £40 ph. This is verbal when quoting and written on quote in black and white. Im not testing on a quote, as far as im concerned if i pick up my tester then im working, and unless the customer would like to pay for a test before then im not doing it.

So what do you do if the customer is on a budget and doesn't have any extra funds. You install the new CU without testing and there's RCD tripping issues, do you just leave them without power, disconnect the new RCD's or put the old CU back in?

 

[dazza1981]

Is a borrowed neutral generally when its been wired in singles?
Im qualified but mainly done new builds since i qualified so i have never come across it.......yet!!!
Thanks

 

[Guitarist]

So was that not the case with this post you tw@?

No need for name-calling.

 

[sima24]

So you are happy to get a reptation for someone who looks for extra work after the event rather than taking a extra half an hour carrying out a bit of work and pass on your findings to the customer before hand?

You dont have to tell them what you have found, just that there will be remedial work required due to your test results.

Again, customer told before hand. An extra half hour on every cu quote, im running a business. I tell every cu change customer that remedial work might be required as until its tested its not clear. I see no difference with any other trade, mechanic is not going to spend half hour of their time for free diagnosing my van before giving a quote. My dentist wont give me a free half hour checkup before a quote for a filling the list goes on.
No disrespect if you do as i said, each to their own but i dont think im doing anything wrong by not working for free

 

[brizospark]

Yeah fault was damaged cable at JB under floor

 

[wersolaruk]

Did u find it anyhow?

 

[brizospark]

Is a borrowed neutral generally when its been wired in singles?
Im qualified but mainly done new builds since i qualified so i have never come across it.......yet!!!
Thanks

Daz a not necessarily a borrowed neutral is where a neutral has been taken from a different circuit to the live. Common in lighting circuits.

 

[brizospark]

As above damaged cable at JB under floor solarman

 

[davethsparky]

So you guys who don't bother testing are happy to give the customer a surprise when the bill doubles at the end of the job?

I don't generally test at the time of quoting, I do test before taking the old CU to pieces though.
I always advise the client that there may be faults in the system and that I will quote seperately to fix them if necessary. But I will fix little faults and things like borrowed neutrals without charging the client any extra. I usually allow a bit of extra time on the job to cover these things and if I finish much quicker than expected with no faults to fix then I will knock a bit off of the bill to reflect this.

 

[Dubbo]

Even if if you didn't test before changing board, that's the risk you take, but shouldn't you have found the faulty circuit during dead tests? Don't think it's very professional just powering up without testing and what readings do you put on your cert?

 

[trev]

Dubbo, if you're the kind of bloke that powers up without testing you're not the kind of bloke that issues certs mate.

 

[brizospark]

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

As previously stated I carry out a visual

 

[Guitarist]

I think that we all accept the fact that there may be additional issues arise when we actually start the job. The point here though, is that for the sake of 10 mins of basic testing (which also lets the customer get to know you), you have a much better idea of what could possibly bite you when it comes to doing the job. This gives the customer a much better idea of whether they can afford to have the work done, plus gives you a much better idea of how much time to allocate the job.

 

[Plonker 3]

So you visit the property at least once, a visual inspection of the bonding doesn't normally mean anything, I have come across several times cables connected either end only to find they have merely stuffed a cable into a cavity to make it look like it is there.

 

[brizospark]

So you visit the property at least once, a visual inspection of the bonding doesn't normally mean anything, I have come across several times cables connected either end only to find they have merely stuffed a cable into a cavity to make it look like it is there.

This gets checked as I am carrying out job. By the sounds of it you are doing most of the work before you have even quoted Dillby

 

[brizospark]

Even if if you didn't test before changing board, that's the risk you take, but shouldn't you have found the faulty circuit during dead tests? Don't think it's very professional just powering up without testing and what readings do you put on your cert?

I would agree that under most conditions that powering up before testing isnt right but on a domestic CU change where there are no circuits added/altered and everything was functional before then like Dr Pepper says the worst that can happen is a tripped RCD, as in this instance, the fault was rectified. This is getting boring now!