Ze of 3.39 ohms!!!

[SPARTYKUS]

Thats only 4 years thats nothing. What can happen in 4 years?

abbi

the complete RCD protection you have installed covers your 'too high' Zs figures. but with this earthing system the RCDs are only an extra layer of protection, the earthing needs repairing as they are obliged to do.

They can and will. i have watched them dig
up the road/pavement/ huge trench just to fit a new head to an old TNS in central Wolverhampton. It was a lovely job. Best earth you'll get. None of this silly " the laws of physics changed in the 50's" TNCS nonsense!!!

 

[Sb8389]

high ze

Hi pal,
Any chance I can pick ur brains
I have recently installed a dual rcd consumer unit and when it came to the testing the ze was 0.70 ohms on a tncs system overhead supply I know this is double the required reading of 0.35 ohms should I contact the DNO and how dangerous is it.would welcome your advice.

 

[telectrix]

0.7 should give you acceptable Zs readings, but it's, as you say, twice the max. allowed on a TNC-S, so get DNO to fix it. it's their problem.

 

[abbi normal]

Update ............. after some buck passing one of the organisations involved have agreed to change the tns to a PME supply to the property at no cost to anyone .... ..... thanks for the input peeps

 

[Guitarist]

It does woory me somewhat that practicing electricians are taking readings for their forms without really knowing what it is they are reading along with which leads to use....

 

[SPARTYKUS]

Update ............. after some buck passing one of the organisations involved have agreed to change the tns to a PME supply to the property at no cost to anyone .... ..... thanks for the input peeps

changing a beautiful TNS to TNCS...... Arrrrghhhhhhh

 

[Rampantchilli]

It does woory me somewhat that practicing electricians are taking readings for their forms without really knowing what it is they are reading along with which leads to use....

and me
i checked some DEIC today done by some subbys working for my employer, at the time of doing the work they also did an DEIRC for the rest of the property, which when i looked had a C1 on it for too high TNS Ze reading, yet they still installed 2 circuits without correcting the issue, and both certs were counter signed too
needless to say they will be going back,

 

[supertoad]

make shure main switch is off before test!

use 3 prong lead -connect all leads on the metrel
the other lead has a plug top on it,

 

[Guitarist]

and me
i checked some DEIC today done by some subbys working for my employer, at the time of doing the work they also did an DEIRC for the rest of the property, which when i looked had a C1 on it for too high TNS Ze reading, yet they still installed 2 circuits without correcting the issue, and both certs were counter signed too
needless to say they will be going back,

And I bet their reply would be.... "Not my problem"

 

[Rampantchilli]

And I bet their reply would be.... "Not my problem"

well its up to me if they get paid, so unless its sorted that aint gonna happen

 

[Scornio]

I had a ze on pme of 0.55 rang up dno they said they'll not be doing anything... Rang up Niceic they said leave it if dno has said to....as long as zs is ok.... Right ok that totally under minds the bgb.

 

[Guitarist]

well its up to me if they get paid, so unless its sorted that aint gonna happen

Good to hear

 

[smiffy911]

I had this problem a few years ago. My Ze reading was 10 ohms. After retesting a few times to double check and check again I rang the dno(Scottish power) and they were out within the hour, dug the pavement up and repaired the supply cable. All done within 4 hours.

 

[Engineer54]

I had a ze on pme of 0.55 rang up dno they said they'll not be doing anything... Rang up Niceic they said leave it if dno has said to....as long as zs is ok.... Right ok that totally under minds the bgb.

I would imagine there are plenty of TNC-S conversions out there with around the Ze 0.55 ohm. Basically means that like many other older converted TN-S cables, they are in the process of full PME conversion!! So long as your Zs values are conforming well, and have additional RCD protection, then you should be fine!!! The BGB and DNO Code of Practice's are very different animals!! ...lol!!