Earthing

[Tomdhu]

I had an electrician installing a new circuit in to the CU and when he did the tests he found that the earth loop impedance was 43.6 Ohms. There is no earthing wire near where the meter is , so he suggested I contact UK Power Networks .I am in South London.
They are scheduled to come next Tuesday. My questions are:-

1. Will they install a proper earth connection/rod at their expense?
2. Are they likely to install an isolator if I ask nicely?

 

[westward10]

Your electrician should have looked at this first. I suspect they will not provide an earth. If that switch supplies your property it needs fault protection by way of an RCD id a TT earthing system is in use.

 

[Tomdhu]

Thanks. The electrician wired in a new radial circuit with two 13 amp sockets into the spare 12th way on the RCD side of the CU. See photo.Is that OK.

 

[Rockingit]

How has your 'electrician' ascertained there's no rod for a TT system already? As I suspect there may be more to this story.

 

[PS Electrics]

Thanks. The electrician wired in a new radial circuit with two 13 amp sockets into the spare 12th way on the RCD side of the CU. See photo.Is that OK.

No not really. First thing that should be checked as Westward said is earthing arrangement. No work should be done if that is not up to scratch which clearly it isn't unless it is TT but it cannot be TT if the Electrician asked you to contact the DNO. The DNO are not responsible for TT Earthing arrangements.

Did you get a Electrical Installation Certificate? You should have, curious to read what Earthing arrangement this Electrician reckons you have!

With regards to if UK Power Networks will provide an Earth they will if they are able to (They have no obligation with regards to an existing supply though) which they will tell you once they have visited your property. If they cannot provide you with an Earth connection point you will have to provide one yourself at your expense.

This would also involve some other work since your Earthing arrangement would then be TT which requires some additional equipment.

 

[Risteard]

No not really. First thing that should be checked as Westward said is earthing arrangement. No work should be done if that is not up to scratch which clearly it isn't unless it is TT but it cannot be TT if the Electrician asked you to contact the DNO. The DNO are not responsible for TT Earthing arrangements.

Did you get a Electrical Installation Certificate? You should have, curious to read what Earthing arrangement this Electrician reckons you have!

With regards to if UK Power Networks will provide an Earth they will if they are able to (They have no obligation with regards to an existing supply though) which they will tell you once they have visited your property. If they cannot provide you with an Earth connection point you will have to provide one yourself at your expense.

This would also involve some other work since your Earthing arrangement would then be TT which requires some additional equipment.

The certificate wouldn't come until the issue is resolved. Granted it should have been checked in advance of the works.

 

[UNG]

If the DNO does not provide an earth then they would need to replace the metal service head as it could become live if a fault occurs, it looks like it needs replacing anyway given it's age
It is quite common to find these service heads where the earth has been removed when installations have been updated and the age of the installation would suggest it has not been subjected to the level of testing that is the norm these days
Usually when I find installations like this I do an earth loop impedance test to the metal service head or the sheath of the incoming cable to check for an earth, had it a few times where the DNO guy tried to claim it was TT when clearly the sheath of the PILC was a good earth and just needed the correct earth flylead and clamp fitting

 

[PS Electrics]

The certificate wouldn't come until the issue is resolved. Granted it should have been checked in advance of the works.

Looks like the breaker is off if that picture is post installation and still says spare so yes you are probably right about that and work not completed yet.

 

[Tomdhu]

The breaker is off and labelled "Spare" because the photo was taken before the electrician did the job. It was sent to him so he could assess the job in advance.

 

[PS Electrics]

Thanks. The electrician wired in a new radial circuit with two 13 amp sockets into the spare 12th way on the RCD side of the CU. See photo.Is that OK.

Looks like there is no RCD protection on your shower unless there is a separate RCD?. I would suggest.

1. You do no use the Shower until the Earthing is sorted.
2. You look to getting the Shower RCD protected.

 

[PS Electrics]

The breaker is off and labelled "Spare" because the photo was taken before the electrician did the job. It was sent to him so he could assess the job in advance.

So is the new circuit the Electrician installed live and working now?

 

[Tomdhu]

Yes, the new circuit is working just fine

 

[Tomdhu]

Looks like there is no RCD protection on your shower unless there is a separate RCD?. I would suggest.

1. You do no use the Shower until the Earthing is sorted.
2. You look to getting the Shower RCD protected.

Good point! The Sparkie didnt mention it.
But it begs the question - should I have an RCBO fitted in that slot? The CU is MK and is 20 years old. Do you reckon it could accommodate the extra height of a compatible RCBO?

 

[PS Electrics]

Yes, the new circuit is working just fine

No need to energise until that Earthing is sorted. They have taken on some liability there.

Good point! The Sparkie didnt mention it.

Ideally none of the circuits on the non RCD side should be on until that earthing is sorted. I only mentioned the shower because you can avoid having one and that would be the most dangerous location to receive an electric shock.

But it begs the question - should I have an RCBO fitted in that slot? The CU is MK and is 20 years old. Do you reckon it could accommodate the extra height of a compatible RCBO?

Discussed here 4 years ago

Thread 'Will an RCBO fit in the MK board?'

Jun 17, 2021

I want to change the 3 MCB's in the picture for RCBO's.
Will the MK ones fit?
Cheers ?

• HappyHippyDad
• board fit rcbo
• Replies: 18
• Forum: UK Electrical Forum

You have sockets in the loft without RCD protection as well.

 

[Tomdhu]

No need to energise until that Earthing is sorted. They have taken on some liability there.

Ideally none of the circuits on the non RCD side should be on until that earthing is sorted. I only mentioned the shower because you can avoid having one and that would be the most dangerous location to receive an electric shock.

You have sockets in the loft without RCD protection as well.

All the responses received have been gratefully appreciated and I have a better understanding of the installation. Given that the CU is 20 years old and was installed by a sub-contractor to the builder who did extensive works back in 2004, then I guess that explains a lot!
The wiring in the CU is a bit of a mess as can be seen below.

I am inclined now to get a new CU with 15 instead of 12 ways so that I can future proof things by having RCBOs all round plus space for a SPD, an EV charger outlet and a 12v supply for things like door bell. The other reason is that I want a decent wiring job done on the new CU - something approaching Artisan Electrics or Dave Saviory quality.

20 years ago, MK was the dog's nuts. Which brand currently has the best blend between quality, features and value?

I am in South London and might post the job on here after UK Power Networks have visited to investigate earthing.