Underground earth from supplier but overhead supply?

[EAST61]

Hi All,

I live in an 100 year old property and I'm curious about the electrics. The house has modern electrics.

I have an overhead electrical supply with only Line and Neutral.

Outside of the property I have a disconnected Earth rod, i.e. no earth cables are attached to it.

I can see that all my mains gas and water have been earth bonded and that they go back to a junction strip outside of the consumer unit and then a single earth cable connects from the strip to the earth bar within the consumer unit. I can then see a main earth cable that goes down from the consumer unit and disappears under the floorboards (which I haven't yet lifted).

Is it possible that I have an overhead electrical supply but the supplier has provided an underground earth connection? Is this called TN-S?

Thank you!

 

[EFLImpudence]

Is the wire which goes under the floorboards not the same one as has been disconnected from the rod?

No, they would not supply underground earth and no, not TNS.

 

[EAST61]

Thank you. I don't know if the cable going down from the consumer unit should be connected to the rod, I was hoping that it would be going back to the supplier somehow. I'll have to start lifting floorboards.

Do you know if houses with overhead electrics can have a separate Earth from the supplier, or is the only option TT?

 

[EFLImpudence]

The supplier would not give you an earth with overhead supply. TT is the only option.

It would appear yours is disconnected.

An electrician to investigate would be advisable.

 

[EAST61]

Thank you very much, I'm on it.

 

[EAST61]

Out of interest, would this be considered an "emergency"?

A property having no earthing sounds terrifying to me, but with all my circuits being RCD protected what is the risk?

 

[EFLImpudence]

Well, it could be (an emergency) if something else goes wrong.

Your gas and water will likely take over the job of earth.
They may be better at it than the rod anyway, but are not technically allowed as the earth these days.

A quick test with the correct equipment would determine this with very little work.

It's the not knowing that is the problem.

 

[EAST61]

I text my spark he said he can pop over on Thursday.

I am starting to wonder if the installer is purposely using the gas pipe as Earth. That sounds bad?

The terminal strip I mentioned before has 3 thin Earth cables connected to it and then a single Earth cable going up to the Earth bar terminal marked "E".

Whereas the gas bonding is 10mm squared Earth cable and goes directly to the consumer unit Earth bar marked "B".

Does that give any clues?

It's a Contactum CU.

Thanks a lot for all your help.

 

[flameport]

I am starting to wonder if the installer is purposely using the gas pipe as Earth. That sounds bad?

Very bad. Gas pipes were never allowed as a means of earthing. Water pipes once were, but that was 50+ years ago.

 

[Tigercubrider]

A lot of pipes are now plastic

Bang goes your earth

 

[EAST61]

The more I look into this the more confused i'm getting.

Here is a picture of the connector strip with 3 earth cables in it that connects directly to 'E' terminal on my CU's earth bar.

I assumed that these 3 cables were connected to various locations around my house, but they are not. They exit my house here:

They go under my brick driveway (away from the house) so I can't work out where they terminate.

The Gas Pipe earth cable attaches to a connection on the mains water pipe and this goes directly back to the CU in 10mm squared cable to the Earth bar terminal B.

Any idea as to what's going on with these 3 earth cables that exit my property? Why are there 3? The are not connected to my Earth rod. Could they go back to the supplier somehow?

 

[ban-all-sheds]

No.

Please stop thinking that you could have any earth cables going back to the substation in any way. You can't, you don't, and they don't.

 

[EFLImpudence]

I assumed that these 3 cables were connected to various locations around my house, but they are not. They exit my house here:
They go under my brick driveway (away from the house) so I can't work out where they terminate.Any idea as to what's going on with these 3 earth cables that exit my property? Why are there 3? The are not connected to my Earth rod. Could they go back to the supplier somehow?

There could be multiple earth rods - and all is well. Although they should be inspectable.

The Gas Pipe earth cable attaches to a connection on the mains water pipe and this goes directly back to the CU in 10mm squared cable to the Earth bar terminal B.

B for Bonding conductor - so correct.
E for Earthing conductor.

 

[Lectrician]

Photos of meter, service head, cables from over head?

 

[EAST61]

You were right, EFL.

Mystery solved.

I managed to dig out one of the earth cables (about 10 inches!) and low and behold it's connected to a rod!

I assume the other 2 are also connected to rods but they are no longer in serviceable locations.

I think this would be a good time for my electrician to do some testing on the rods and install new ones if necessary.

I think the disconnected rod that I mentioned was a bit of a red herring and this was originally installed to connect directly to the gas mains, but in recent times this was changed and now connects back to the CU instead.

Thank you so much for your help, my mind won't be fully at ease until the tests are done, but nevertheless I'm happy to have figured out what's going on.