Weird setup

Londoner2 · 16 Jun 2021

House 1930's terraced in London.

Nest door neighbour landlord phones me to tell me his house has failed a earth impudence test and his electrician reckons main power cable is coming from my house.

I check and yes, i have 3 phases in my house with 3 main 100am fuses , 1 is mine , 1 is next door and 1 spare. My earthing is coming form a clamp tied to main incoming cable but i can only see the live and nuetral cable going through the wall and next door.

He said the DNO will be around to look.

What are the options as i dont want the dno to drill hole into wall to poke a earth through, can they have a look and say they will just install a MEP in their house and thats it?

AndyPRK · 16 Jun 2021

A picture of the cable gonig thru the wall would be nice.

Is it is conduit / metal tube ?

Londoner2 · 16 Jun 2021

AndyPRK said:
A picture of the cable gonig thru the wall would be nice.

Is it is conduit / metal tube ?

I'll take one this eve, there are no conduit/tubes, i can just see a red and black cable going into the partywall.

davelx · 16 Jun 2021

A picture of your neighbour's installation would also help

flameport · 16 Jun 2021

Londoner2 said:
i dont want the dno to drill hole into wall to poke a earth through,

That's not a valid solution, and having the fuse for your neighbours property on your side isn't good either.
Proper solution is for the neighbour to have their own entirely separate supply installed. with their own cutout/fuse on their side, unrelated to yours.

Londoner2 · 16 Jun 2021

flameport said:
That's not a valid solution, and having the fuse for your neighbours property on your side isn't good either.
Proper solution is for the neighbour to have their own entirely separate supply installed. with their own cutout/fuse on their side, unrelated to yours.

I think its been like this since 1930's, neighbour had a loft conversion done in 2006 and nothing was touched on my side, if he wants the fuse on his side he will need to get the dno to install it and decommission from my side.

AndyPRK · 16 Jun 2021

And if he wants an EV car charger, he would need to have a new supply put in anyway

Londoner2 · 16 Jun 2021

AndyPRK said:
And if he wants an EV car charger, he would need to have a new supply put in anyway

Its full of tenants with no interest in cars.

SUNRAY · 16 Jun 2021

Londoner2 said:
I think its been like this since 1930's, neighbour had a loft conversion done in 2006 and nothing was touched on my side, if he wants the fuse on his side he will need to get the dno to install it and decommission from my side.

Having a 2 or 3 phase supply into one property was fairly common right into the 70's and possibly 80's where the fuse box was in the cupboard or as many called them 'shed' near the front door, My sisters first house was like that.

SUNRAY said:
The word 'shed' is somewhat unintuitive. The irony is I have worked in 2 such properties recently but they are both in pedestrian walkway locations and not visible on Street View, hopefully this sketch will offer a better idea:

Typically there are a pair of walk in cupboards, my 2 recent are ~3x3ft and 5x3ft, which are often crammed to the gunwals with the sort of things usually found in the garden shed. It usually contains the meters and CU and commonly one has the I/C services. With a single head it's a perfect example of my 'Two Services'. May be 2ph but bearing in mind these date from >40years ago when power demand was nowhere near todays it's commonly 1ph with 2 fuses and sometimes even just the one fuse.

If we're still referring to OPs situation either #3 or #4 could very easily be appropriate

Guitarguy · 16 Jun 2021

Sounds like a very old method of getting power to the adjacent property, it’s very common in old installations, next door was only ever supplied with live and neutral and historically earthed via a rod or lead water main.
There are a few options-
1- replace the three phase cutout with a new one (done dead) and loop a split concentric service off for next door off the incoming side of one of the phases, thus avoiding it being fused your side and the earth can be connected to the lead sheath- might involve a new hole in the wall if the cable can’t be put through existing.
2- leave it like it is and his supply will need to have TT earthing
3- Have a new supply installed off the main out in the footpath for next door to separate it all completely.
It would be up to the DNO to decide what they want to do really.

wundaboy · 16 Jun 2021

One thing to consider, seeing as their supply is fed from your service head, is that if their earth is poor it probably means yours is too. Something else to bring up with th DNO when they call.

But yes, as a wider point, next door should have its own supply separate to yours, and you should push for the two properties to be electrically separated.

SUNRAY · 16 Jun 2021

My suggestion would be to replace the fuse with a link and add a second cutout the correct side of the wall.

Earth would have to follow a survey.

SUNRAY · 16 Jun 2021

wundaboy said:
One thing to consider, seeing as their supply is fed from your service head, is that if their earth is poor it probably means yours is too. Something else to bring up with th DNO when they call.

But yes, as a wider point, next door should have its own supply separate to yours, and you should push for the two properties to be electrically separated.

It is still a common set-up though.
My own incomming feed is looped to the neighbour. Admittedly not fused in my house though.

Londoner2 · 16 Jun 2021

wundaboy said:
One thing to consider, seeing as their supply is fed from your service head, is that if their earth is poor it probably means yours is too. Something else to bring up with th DNO when they call.

But yes, as a wider point, next door should have its own supply separate to yours, and you should push for the two properties to be electrically separated.

In an ideal world splitting would be ideal, should have ben done when i had my extension done in oct 2019 but i wasnt aware then. The thing is i had my loft converted in 2016 and new extension in 2019 with new circuits added and new CU fitted and building regs passed and on both occasion the electrician did not point this out to me, i dont know as part of his circuit testing if he has to do the earth looping test as well.

davelx · 16 Jun 2021

Londoner2 said:
i dont know as part of his circuit testing if he has to do the earth looping test as well.

Yes, he does - but on your side, from your description you have a TN-S installation which uses the sheath of the cable for the earth and the test results would probably have been fine. It appears that this has not been extended to your neighbour. So we would really like to see a picture of the earthing arrangements on your neighbour's side.

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Weird setup

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