RCD earth potential

[Stringy75]

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. 




 

My attitude is a response, I am being attacked, I am responding to vicious, insulting attacks. I am not the one initiating the insults.

I thought there was a correct order in which the test should be carried out ? ie R2 before IR  

We were not commissioning the installation we were fault finding.

 

[Murdoch]

If and I say IF it was a simple polarity issue, you would have spotted it straight away when you did a Ze.

The importance of the Ze can not be under estimated - it confirms polarity AND the quality of the earth (if the DNO is providing one!)

Will you have the decency Gigsy to update the other forum?

NB: I'm still very confused as to why you went to the site in the first place!

 

[poni]

Polarity at the distributor's  isolation switch

this should have been a 5min job, its taken me longer to type this,

 

[Stringy75]

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?




 

What question have I not answered?

I rest my case




 

Good

 

[ProDave]

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.

Quite.

You know how some DNO's like to write L and N on the tails out of the meter. I have a photo somewhere where the DNO had labelled them backwards. Now If I had assumed he had labelled them correctly.........
 

What question have I not answered?

What the reported fault was that you went to the property for?

And what the eventual fault that was giving you the funny readings turned out to be.
 

 

[Sharpend]

My attitude is a response, I am being attacked, I am responding to vicious, insulting attacks. I am not the one initiating the insults.

The thing is you ask a question, an answer is given/ a question raised, you respond with vague answer or none at all. Remember on a forum of any type the person asking the questions can only be judged upon the question and or answer they give, we do not know you personally so can not say for sure what you may or may not know, so your responses are important to demonstrate to those you seek help from where you are with your understanding, many on here are very experienced and established electricians  that very rarely have to ask a question on basic electrical principles, so can be easily insulted if you reject the help they offer?

 

[Sidewinder]

Stringy,

You really need to go back and, take time to, actually read the words written by previous posters, then answer the words that are written, not what you think they have writtemn, or what you want them to have written.

There is a lot to be said for logical fault finding.

The procedure that you have posted so far does not sound to me like logical fault finding.

 

[Stringy75]

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.




 

After the meter there is an isolation switch, reversed thewre

 

[poni]

We were not commissioning the installation we were fault finding

get the basics right when the rest will follow , how would know if there was a nail/screw through the cable if you don't do the R2 first,if the cpc is cut by the nail then the IR test will tell you nothing but the cable is OK up until the cut,

 

[Manator]

My attitude is a response, I am being attacked, I am responding to vicious, insulting attacks. I am not the one initiating the insults.

You are being attacked, but why? Firstly I would presume that you have not listened to any advise. If you are truly new to the game, then take a deep breath.

My advise is never assume anything, besides the old adage, it really does serve you well in later life. Any fault, intermittent or otherwise can be found, it just takes in depth testing that most people do not do.

For instance I was called out to a school this week that had an intermittent tripping fault, 4 electricians had been previously to try and find the fault. I spent an hour and located a damaged leg on a ring circuit. How?? I tested everything and did some hard dismantling something that the previous guys never did. Am I better than they? not really just more diligent.If you really want to learn never assume that after a couple you know everything, I don't and I am nearly ready for retirement.

 

[Sharpend]

After the meter there is an isolation switch, reversed thewre

On which side of the isolator was the incorrect termination incoming or outgoing?

 

[Murdoch]

After the meter there is an isolation switch, reversed there

which one of you would have spotted if you had done a Ze when you started or shortly after. I'm STILL confused as to why you were there .....

I've just come in from an evening call out - the call out was due to a "noisy" fuseboard. After checking ALL the connections inside, and finding the incoming neutral very loose, I then checked the Ze. This confirmed the polarity and the quality of the suppliers earth. Simples.

 

[ProDave]

After the meter there is an isolation switch, reversed thewre

So the INSTALLER who did the CU change connected the tails from the output of the isolator to the new CU the wrong way round.

So THAT was the eventual fault (that was like getting blood out of a stone)

It is almost certain you could have spotted that error visually in a few seconds before you even got the tester out.

That also clearly shows the original installer who did the CU change did not do any testing then did he, other than perhaps "the lights work, job done"
 

 

[Murdoch]

That also clearly shows the original installer who did the CU change did not do any testing then did he, other than perhaps "the lights work, job done, can I have my CASH please"
 

edited that for you!

 

[Stringy75]

If and I say IF it was a simple polarity issue, you would have spotted it straight away when you did a Ze.

The importance of the Ze can not be under estimated - it confirms polarity AND the quality of the earth (if the DNO is providing one!)

Will you have the decency Gigsy to update the other forum?

NB: I'm still very confused as to why you went to the site in the first place!




 

How can measuring  the resistance of the external earth prove polarity?




 

 

[Sharpend]

Will your tester not scream at you that the connections are wrong?

 

[Stringy75]

get the basics right when the rest will follow , how would know if there was a nail/screw through the cable if you don't do the R2 first,if the cpc is cut by the nail then the IR test will tell you nothing but the cable is OK up until the cut,




 

Why is this so hard? You are all experienced electricians. We had a potential difference between neutral and earth, the thinking was the nail had cut through the installation of the line and was making a connection between line and earth, making the earth live

 

[Sidewinder]

Stringy,

What does GN3 tell you about Z testing?

I suspect that will answer your question to Murdoch, so pull your copy and have a look?

 

[Manator]

Before you reply try and think how stupid you may come across.

 

[Sidewinder]

Why is this so hard? You are all experienced electricians. We had a potential difference between neutral and earth, the thinking was the nail had cut through the installation of the line and was making a connection between line and earth, making the earth live

Stringy,

Think about this please.

How can that happen, IF, the installation, and supply are correctly wired, without operating a protective device?