RCD earth potential

[Sidewinder]

Stringy,

Welcome to the forum.

I've skimmed through the whole thread, there are several issues that I could go and make issues out of, but, I'm not going to.

I am going to single out one sentence, and it's the last sentence you posted before I began to write this.

You used the word "assumed".

Now I specialise in fault finding, investigation and rectification, and some of the kit I work with & on is stupid money.

One piece of advice I would give you is NEVER assume.

All it does as the old saying goes is make an ASS out of U and ME.

Whilst I get your point that you would have expected that the original installer did the required tests, and did their work in  a competent manner, in this scenario, it seems by its very nature, this was not the case, so you need to go through everything from first principles to check and prove that everything is correct, and assume nothing.

 

[Manator]

A nail driven through a cable would take a competent electrician about 5 minutes to find with proper testing. I just love part P. It gives van drivers the right to call themselves electricians.

I am not calling you or your mentors van drivers, just that I am not calling you electricians either.

 

[Andy™]

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.

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

never assume anything. check everything for yourself starting with the basics. but Dave is right, the 'electricians' you work with do seem incompetent. no idea what the actual fault is, but any decent spark should be able to identify it  in a reasonably short time

 

[ProDave]

Assume = ASS of U and ME

So Stringy, what was the fault? I take it you have been back today and resolved it? I genuinely want to know what was wrong in the end.
 

 

[Stringy75]

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?

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.  




 

I know you cannot verify polarity by looking at the cable colours, I find your comment very patronising, I have passed the C&G inspection and testing exam, as I have previously stated.

The electricians I was working with are very experienced and skilled, I find your comment very insulting.

You are incorrect in saying a fuse or MCB would pop if there was a fault between L&N or E. That would depend upon yoiurZs value. School boy error.

I accept your point about the scale of an insulation resistance tester, you miss the point. If there was a short between live and earth I am saying we would have got a reading of 0 ohms from said test. As we had a reading of >999 ohms I am saying there was not a short between line and earth. This is basic stuff, you have allot of front stating the men I work with have no experience or skill and then going on to make this statement.

We didnt do a Ze test because a fault on the distribution companies side is unlikely and we did an IR test 1st cos we suspected a nail had been driven into a cable as work is being done at the house. There is no rule to say which test to do 1st and a nail being driven through a cable was more likely given the circumstances than a fault with the earth at the distribution companies side. Aslo we assumed a Ze and polarity test would have been done before commissioning the installation.

I have passed C&G 2392, as already stated, please read threads before asking the questions.

We did a basic test, we did an installation resistance test, didnt have time to do all the basic tests, we do not have to do the tests in the order you say.

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




 

Yes it was dark when we finished, very observant. You would make a good detective.

 

[Stringy75]

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.




 

We did not sign the installation off, we knew the symptoms of the fault on the circuit. The installation is not in commission

A full series of tests will be done before the installation is brought into commission. Rome was not built in a day. We had to diagnose the fault before doing a full series of tests and commissioning the installation

 

[Stringy75]

Stringy,

Welcome to the forum.

I've skimmed through the whole thread, there are several issues that I could go and make issues out of, but, I'm not going to.

I am going to single out one sentence, and it's the last sentence you posted before I began to write this.

You used the word "assumed".

Now I specialise in fault finding, investigation and rectification, and some of the kit I work with & on is stupid money.

One piece of advice I would give you is NEVER assume.

All it does as the old saying goes is make an ASS out of U and ME.

Whilst I get your point that you would have expected that the original installer did the required tests, and did their work in  a competent manner, in this scenario, it seems by its very nature, this was not the case, so you need to go through everything from first principles to check and prove that everything is correct, and assume nothing.




 

Thank you very much for your invaluable advice and passing your experience on to me

 

[Andy™]

erm... if you had done the full tests before the installation was 'brought into commission' then there wouldnt have been any issue with odd voltages because any faults would have been picked up on the dead testing...

most likely scenario here is you have done a re-wire, board change or whatever it is this hour, your plug in tester did not say 'correct' so you done a few voltage readings and are now confused because its not what the 5ww course told you it should be and you now need help to fix it...

 

[Stringy75]

A nail driven through a cable would take a competent electrician about 5 minutes to find with proper testing. I just love part P. It gives van drivers the right to call themselves electricians.

I am not calling you or your mentors van drivers, just that I am not calling you electricians either.




 

It was not a nail driven through a cable and we would have found it in 5 minutes if it was. What is your point?

never assume anything. check everything for yourself starting with the basics. but Dave is right, the 'electricians' you work with do seem incompetent. no idea what the actual fault is, but any decent spark should be able to identify it  in a reasonably short time




 

Your comment is very insulting and not helpful at all

Assume = ASS of U and ME

So Stringy, what was the fault? I take it you have been back today and resolved it? I genuinely want to know what was wrong in the end.
 




 

Polarity at the distributor's  isolation switch

 

[Stringy75]

erm... if you had done the full tests before the installation was 'brought into commission' then there wouldnt have been any issue with odd voltages because any faults would have been picked up on the dead testing...

most likely scenario here is you have done a re-wire, board change or whatever it is this hour, your plug in tester did not say 'correct' so you done a few voltage readings and are now confused because its not what the 5ww course told you it should be and you now need help to fix it...




 

Please do not comment on this thread, you have not read anything I have written, you are insulting and your comments are not helpful

 

[Sidewinder]

Stringy,

Your comments to date are not conducive with getting positive responses from other members.

Your comments seem to be often at odds with others you have made.

What happened today when you went back?

Why didn't you undertake basic safety tests in the light of the fault reported.

IF, the issue is (was) reversed polarity, that is a potentially lethal fault which really needs some serious immediate action, and an install should not ever be left in that situation without a solution plan in place.

 

[Andy™]

ive read enough of it to know that you / your 'electricians' are not competent. maybe go back to playing with a AA battery. at least that way you are a lot less likely to kill someone

 

[Stringy75]

Is this a legit electricians forum or is a place trolls hang out?

ive read enough of it to know that you / your 'electricians' are not competent. maybe go back to playing with a AA battery. at least that way you are a lot less likely to kill someone

your opinion means nothing to me

 

[Andy™]

Is this a legit electricians forum or is a place trolls hang out?

well most of us are legit electricians. you fit nicely into the 2nd category, but i doubt you will be hanging out for long

 

[Sharpend]

Stringy your attitude is very attacking? 

What you are telling us is that you work with two competent electricians and you yourself have the C&g 2392 testing cert, however  three highly trained minds failed in the fundamental basic of testing sequences as outlined in the IET GN3. All the guys are saying is had you applied the sequence as given in GN3 then you would most likely have established the fault, rather than Assuming in your approach, and subsequently not wasted the time that you did have to fault find by doing uneccesary things and now having to have a return visit.

I'm taken back by your own admission of being a trainee yet rejecting the advice and guidance of those that YOU sought advice from here? If you are keen to learn then draw from the replies the valuable information and experience that is offered and take it on board to improve your knowledge and approach to future fault findings?

please do update us as to your findings upon your retrun visit. 

 

[poni]

There is no rule to say which test to do 1st

I thought there was a correct order in which the test should be carried out ? ie R2 before IR,  cant find my book at this time of night for the complete list in order, but as Stringy has just passed his 2392,maybe has can help?

 

[steptoe]

ERM,

How do you get reverse polarity at the distributors isolation switch,?

You mean that the installer that connected the consumer unit tails to the switch connected them to the wrong terminals,?

The distributor can do whatever they want, its up to the installer to prove polarity and connect the consumers equipment accordingly.

 

[Sidewinder]

Is this a legit electricians forum or is a place trolls hang out?

your opinion means nothing to me

Stringy,

Why are you being so negative?

You are posting very unusual answers, and not answering the questions asked of you by other members, yet, you insist on attacking them, when they question the vague, or unusual answers that you give to them?

 

[Manator]

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

It was not a nail driven through a cable and we would have found it in 5 minutes if it was. What is your point?

I rest my case

 

[Andy™]

ERM,

How do you get reverse polarity at the distributors isolation switch,?

You mean that the installer that connected the consumer unit tails to the switch connected them to the wrong terminals,?

The distributor can do whatever they want, its up to the installer to prove polarity and connect the consumers equipment accordingly.

think you may have hit the nail on the head there. but at least not through the cable, he's already checked that