TNCS High ZE at origin

[AdamGiguere]

Hi there

Testing at origin of a domestic property, I have found:

L-N: 0.44 Ohms
L-E: 9.89 Ohms

I had the DNO attend clients address, there response was that it was quite high and confirmed readings of 0.44 for ZE. (Pleasee attached document with their response)

My concern is they don't seem to have checked the reading between L-E......

Anyone know what could be the cause of this? MET connections are tight and in good condition....

Many thanks in advance.

Adam

 

[Ian1981]

 

[AdamGiguere]

The cut out does not come with the earth brass bar as shown above the 25mm earth comes from elsewhere - I'll have to investigate further.

As there must be a problem with the earthing connection?

Just baffling as to why the DNO have not picked this up, would they have just done the test between L-N?

Surely not?

 

[AdamGiguere]

The MET is just screwed on next to the cutout

 

[Ian1981]

Any pics?

 

[AdamGiguere]

Not of the origin - I should have. Apologies...

I'll question the DNO tomorrow when I call.

I'll have to return to the site. There must as you mentioned be something wrong with the earth connection but I couldn't for the life of me see anything wrong earlier when I was looking....

 

[westward10]

If they are telling you it is PME and you are getting those readings then you have no link between the earthing conductor and supply neutral.

 

[westward10]

View attachment 37268

You been in my garage.

 

[Ian1981]

You been in my garage.

And I thought my garage was a mess

 

[AdamGiguere]

If they are telling you it is PME and you are getting those readings then you have no link between the earthing conductor and supply neutral.

Yes that's what it would seem right.

There must be a problem with the link but just wondering why the DNO have not picked this reading up....?

Would they have just tested between L-N ?

 

[westward10]

Possibly you need to get back in touch with them.

 

[AdamGiguere]

I'll call them tomorrow, shall let you know the outcome...

Many thanks for all your responses - most appreciated

Adam

 

[Wilko]

Yes that's what it would seem right.

There must be a problem with the link but just wondering why the DNO have not picked this reading up....?

Would they have just tested between L-N ?

Hi - from their wording, they have provided you with a PME means of earthing. However given the 9 Ohms Ze, it seems it's not been connected to the installation's MET (by you )

 

[Davisonp]

I cannot see anywhere that it states that the property is currently a PME system. In fact, the OP says “the 25mm earth comes from elsewhere - I'll have to investigate further” so it looks like it is currently a TT or TNS system. The DNO actually seem to be saying they made a decision to provide PME tails for an electrician of choice to connect into the excising setup. I suspect they have not done this yet and will do the actual conversion when an electrician is present.

Are you sure this is not a TT system?

 

[buzzlightyear]

When you say the "cut out" what do you mean?

a thingamabob you put a fuse in .

 

[westward10]

I cannot see anywhere that it states that the property is currently a PME system. In fact, the OP says “the 25mm earth comes from elsewhere - I'll have to investigate further” so it looks like it is currently a TT or TNS system. The DNO actually seem to be saying they made a decision to provide PME tails for an electrician of choice to connect into the excising setup. I suspect they have not done this yet and will do the actual conversion when an electrician is present.

Are you sure this is not a TT system?

Just reread all this and you are quite correct. OP where does the 25.0 earthing conductor go to I probably wrongly assumed it went to the head.