high zs reading tn-s

[cvickz]

Hi I have a site to check due to high as readings. I have been told that an electrician was there to carry out a condition report. He said he had good readings on first 2 db's he tested (arround 0.24) then he tested the third ok. Then he tested a circuit on the third db which gave a reading of 7.56ohms. He tried another circuit on third db and this also had a reading above 7 ohms. Then he retested the third db which had gone up by arround 7 ohms. Confused he went to prove his earlier testing on first two db's and they too had gone up. The last thing he tested was at henleys and met which sits at 7.33 ohms. What could have caused this during testing. Plus I am also changing earth conductor size from met to income from 6mm to 16mm.

Any help much appreciated
thanks

 

[westie101]

A reading of this value on the incoming supply should be IMMEDIATELY passed to the DNO for attendance

 

[RF Lighting]

Why isn't your electrician reporting / resolving this?

I always report high Ze on the customers behalf.

 

[cvickz]

He has now left the company for other reasons but he got away with it because he said his megger tester was faulty rather than there was a problem on site. U now have his megger tester and it works fine, I am told it has not been repaired or anything since he had it.

 

[EFLImpudence]

One of the leads became loose. ?

 

[RF Lighting]

He has now left the company for other reasons but he got away with it because he said his megger tester was faulty rather than there was a problem on site. U now have his megger tester and it works fine, I am told it has not been repaired or anything since he had it.

How long has this fault been left like this

 

[cvickz]

I'm hoping it's something that simple, the site is empty at the the moment (it's a pub) and the main isolator it's off until new tenants are in

 

[ban-all-sheds]

He has now left the company for other reasons.

So what's your relationship with the company?

Are you an electrician?

 

[cvickz]

Think it was tested at the weekend

 

[securespark]

Why isn't your electrician reporting / resolving this?

I always report high Ze on the customers behalf.

Yup. I get straight on the blower.

 

[cvickz]

And yes I am an electrician, never had this issue before though where it goes up during test. And megger seems ok ?

 

[RF Lighting]

Are you sure?

Surely re-testing the Ze with a different meter is a very simple and obvious way to tell you where the fault lies?

 

[ban-all-sheds]

You've only got the word of your now-departed predecessor that it did change during testing.

 

[cvickz]

I have two megger Testers I am taking tomorrow mine and newley departed, if it is high I will be contacting supplier asap. Thanks for replies guys.

 

[westie101]

if it is high I will be contacting supplier asap

NO
Not the supplier - they are who folk buy electricity from

BUT

The DNO who operate the network and deliver the electricity to site