RCD earth potential

[Lurch]

Not very helpful though!

Oh, I thought you were just the trainee? I now realise I was wrong to suggest that someone competent should have performed basic testing on an installation following the fitting of a consumer unit. Thanks for letting me know I have been doing it wrong all these years.

If you know all the answers why are you here?

 

[poni]

2 electricians on site are incompetent

this could also be true

 

[Stringy75]

I passed C&G 2392 last week with a score of 41/50. We was not there to commission the installation, we were fault finding. Please stop trolling me

Oh, I thought you were just the trainee? I now realise I was wrong to suggest that someone competent should have performed basic testing on an installation following the fitting of a consumer unit. Thanks for letting me know I have been doing it wrong all these years.

If you know all the answers why are you here?




 

I passed C&G 2392 last week with a score of 41/50. We was not there to commission the installation, we were fault finding. Please stop trolling me

 

[Stringy75]

sound's like a top electrician, saving on tape!

maybe not the MET, but something to do with the final connection's to it, tail's or earth bond,




 

Well it was not actually a MET. Main earth came from distributors fuse box to a terminal, from terminal to consumer unit. There was continuity from that terminal to the consumer unit, I will do a Ze test tomorrow to be sure, thank you

 

[poni]

the earth looks sound its the neutral I'd look at , as you have 230v to earth from it, what was phase to earth?

sorry did you say it had been rewired? if so why the  chock blocke's

 

[Stringy75]

the earth looks sound its the neutral I'd look at , as you have 230v to earth from it, what was phase to earth?

Line to earth was 0V

 

[Doc Hudson]

In my opinion when encountering anything unexpected or strange, you should start off by isolating the power and verify the supply coming in is all good and electrically sound. e.g. polarity, earth loop impedance (or ra if TT), prospective fault current. Regulation 132.16 does state checking incoming supply, earthing & bonding before doing alterations. So if no one has done a Ze, has anyone actually verified polarity. L & N reversed would give 'apparent 230v N->E  and 0v L->E. Tails crossed between Cu & meter possibly. 

Doc H.

 

[poni]

Line to earth was 0V

this does not sound right both neutral and earth 0 v, then its the polarity that needs checking

 

[Stringy75]

In my opinion when encountering anything unexpected or strange, you should start off by isolating the power and verify the supply coming in is all good and electrically sound. e.g. polarity, earth loop impedance (or ra if TT), prospective fault current. Regulation 132.16 does state checking incoming supply, earthing & bonding before doing alterations. So if no one has done a Ze, has anyone actually verified polarity. L & N reversed would give 'apparent 230v N->E  and 0v L->E. Tails crossed between Cu & meter possibly. 

Doc H.




 

Well we didnt get there till quite late in the day, we ran out of time, the two electricians started investigating the ring mains 1st, maybe an error on their behalf, they found a fault in the ring mains. It was a case of more than one fault.  I guess from their experience they knew what that fault was, and they were right, the ring mains were wired up wrong. The next thing they did was insulation resistance testing, this test would flag leakage between the live conductors and earth and also a short between the line conductors and earth, which would give a resistance of 0 ohms. While doing the insulation resistance test they re-wired the consumer unit because it was a rats nest and they wanted to change put the downstairs circuits covered by one RCD and upstairs covered by another RCD, as before lights were covered by one and sockets by another.

We didnt make any alterations as such, we were concentrating on finding faults.

We did not check live polarity. I think you have hit the nail on the head. Polarity reversed at the distributor's isolator could well explain some of the odd readings we were getting, i think. A live polarity test is what I will suggest we try tomorrow 

this does not sound right both neutral and earth 0 v, then its the polarity that needs checking

I think you are right, Polarity reversed at the distributor's isolator does seem to make sense!!

 

[Murdoch]

I'm gob smacked that 2 sparks and 1 trainee didn't check the incoming supply...... all sounds a bit smelly IMHO

 

[ProDave]

I am sorry to say it, but I share the opinion of others, that the two electricians are incompetent, which is a shame as they are the ones supposed to be training you.

It to me is sounding more like reverse polarity, but it should be simple to test that and that should have been tested before energising the board.

At this point I feel sorry for the customer. They had an incompetent electrician do a poor rewire, now the guys called to Fix it don't seem a great deal better.

And Stringy, I am not having a go at you, I feel sorry for you as well as your mentors do not appear up to scratch so they can't be training you very well.

If you go back today, take some pictures of the supply head, meter, and consumer unit and post them here please.


 

 

[kerching]

2 electricians worked on the board, worked on the ring main, did not check polarity!

REALLY?

 

[Doc Hudson]

Well we didnt get there till quite late in the day, we ran out of time, the two electricians started investigating the ring mains 1st, maybe an error on their behalf, they found a fault in the ring mains. It was a case of more than one fault.  I guess from their experience they knew what that fault was, and they were right, the ring mains were wired up wrong. The next thing they did was insulation resistance testing, this test would flag leakage between the live conductors and earth and also a short between the line conductors and earth, which would give a resistance of 0 ohms. While doing the insulation resistance test they re-wired the consumer unit because it was a rats nest and they wanted to change put the downstairs circuits covered by one RCD and upstairs covered by another RCD, as before lights were covered by one and sockets by another.

We didnt make any alterations as such, we were concentrating on finding faults.

We did not check live polarity. I think you have hit the nail on the head. Polarity reversed at the distributor's isolator could well explain some of the odd readings we were getting, i think. A live polarity test is what I will suggest we try tomorrow 

I think you are right, Polarity reversed at the distributor's isolator does seem to make sense!!

Your opening statement is irrelevant, the time of the day has no bearing upon standard fundamental checks when working on an installation you have never been to before. If it is reversed polarity (NOTE: you cannot verify polarity of an installation by looking at cable colours), then both of the others are no more skilled or experienced than you are. I think you would know very quickly if there was a 0ohms short between L & N or E. A fuse or MCB would be popping the minute you tried to energise. Using  an insulation resistance tester will not give you a 0ohms reading. The scale is MegOhms, typically with two decimal places. so the smallest reading you could get is 0.01 M which is 10,000ohms. You would need a low resistance continuity tester to get any readings 9,999ohms or lower.  I am finding this whole scenario a bit far stretched; you say you got there late, but you also took the whole consumer unit off the wall and re-tested all circuits and then wired it all back up, with fault uncleared, BUT during all this you never did a Ze or Polarity test?

 We actually took the consumer unit off the wall, disconnected everything and took it off the wall and did insulation resistance tests on all the circuits, then put the consumer unit back on the wall and wired it up. The fault was still there.

Have any of you working at the installation (including the original "electrician") passed any formal city & guilds electrical courses in the UK?  Original "electrician" has tried to fit a dual RCD board without testing any circuits first, presumably found RCD's tripping due to crossed circuit wiring. So just bangs wires here there and anywhere to get power on without RCDs tripping. Another group of "electricians" arrive to investigate problems and still no one does basic checks. Unbelievable.

Doc H.  

 

[ProDave]

And if they "arrived late" they must have ripped the board off the wall and re fitted it in the dark.
 

 

[binky]

enough of the character assination! Late afternoon job, in a rush, lots of faults, mistakes get made. I've done it myself, and will probably do it again at some point in time (hopefully  not as I am suppossed to learn from previous daftness).

 

[Lurch]

We was not there to commission the installation,

You removed the consumer unit and then installed it with no basic testing done. Doesn't matter how many points you got in your quiz, that is not what a competent electrician would do. The work done by you is no different to doing a consumer unit change.

Pointing out where someone is doing something wrong is not "trolling". If you know all the answers then get yourself back to site and fix the problem rather than coming here looking for positive reassurance of your erroneous methods.

 

[Murdoch]

How rude!! Thank you for sharing your opinion, Not very helpful though!

Maybe you should alter the tone of your responses - as I recall this is why you got a ban on the other side.....

 

[Sharpend]

I suspect that Stringy works for one of those Niccy firms that churn out apprentices and then electricians from a young age but having very little knowledge or experience other than doing what they're told probably by someone not much older than themselves?? 

But as the company is Niccy endorsed it's must be ok. 

 

[binky]

in my experince the bigger not-so clever companies tend to be NAPIT registered. Either way such speculation isn't helpful and unnecessary.

Must be something to do with the time of year, lately this forum is more like 'grumpy r us' :^O

 

[Stringy75]

I am sorry to say it, but I share the opinion of others, that the two electricians are incompetent, which is a shame as they are the ones supposed to be training you.

It to me is sounding more like reverse polarity, but it should be simple to test that and that should have been tested before energising the board.

At this point I feel sorry for the customer. They had an incompetent electrician do a poor rewire, now the guys called to Fix it don't seem a great deal better.

And Stringy, I am not having a go at you, I feel sorry for you as well as your mentors do not appear up to scratch so they can't be training you very well.

If you go back today, take some pictures of the supply head, meter, and consumer unit and post them here please.


 




 

You are very opinionated, the electricians I worked with are not incompetent. 

We didnt do the rewiring, as you rightly pointed out, polarity along with all the other tests should have been carried out before the board was energised, this would lead an intelligent person to assume something happened after that point in time, ie a nail going through a cable, that was where our investigation started.

The guys called to fix it are good men, who do not judge other people without knowing them and knowing all the facts about a situation.

Do not feel sorry for me, I love the work I am doing and have the most respect for the people I am working with.

2 electricians worked on the board, worked on the ring main, did not check polarity!

REALLY?




 

Nope we thought it was a nail being driven through a cable, we assumed a polarity check would have been mad before commissioning