Looped DNO supply? Any thoughts?

[Gavin John Hyde]

Looking at a house today doing the pre-site visit and tests for a partial and maybe full rewire.
The supply is what i think is known as a looped service.
Not come across one and had to do work on it before. other than seeing them around and not much thought given to it.
The supply comes in to the house and then terminates in the supply head before exiting and going on to the next property. this could be just 2 or even the whole street.
Once terminated it goes off to the meter, cu etc... If the labels are correct it is running a 60 amp fuse from the DNO. I am surprised it hasn't gone given the amount of stuff running in this house.
There is a earth coming from one of the cables and unless i am mistaken it s TNS.
I had a look at the neighbours supply head out of curiosity as the owners said they had work done recently and they have had the service head changed and now theirs is PME...

What can you guys tell me about this looped service set up...

its intrigued me a bit as it seems quite dated. It just don't sit right with me having the mains supply coming up into the property for around 18 inches then going off back in to the ground running to the neighbours...

It does pose the question if they are all interlinked would a breakage or major fault at say the first house in the cul de sac kill the whole lot of supply for all houses connected?

 

[Richard Burns]

Looped supplies are not so common now but they were a method of reducing the amount of cable needed especially on estates and cul de sacs.
The attached picture is a looped supply on TNS earthing.
It would mean that if the first supply head cable were separated (not very likely) the following houses would be disconnected, which is probably why they do not do it now, they tend to do underground joints which then fail!
They tend to do a few houses on one phase then a few houses on the next and so on.
It is not something that should affect any work you do. Just make sure you are not messing around with the incoming cable.

 

[davesparks]

Once terminated it goes off to the meter, cu etc... If the labels are correct it is running a 60 amp fuse from the DNO. I am surprised it hasn't gone given the amount of stuff running in this house.

The amount of stuff doesn't necessarily relate to the actual current being drawn by the installation, it is highly unlikely that a regular domestic installation will ever bother a 60A fuse.

 

[Gavin John Hyde]

The amount of stuff doesn't necessarily relate to the actual current being drawn by the installation, it is highly unlikely that a regular domestic installation will ever bother a 60A fuse.

Diversity is a wonderful thing. In life and electrics... With it we achieve so much more...

 

[mhar]

You can ask the DNO to remove the supplies to the other properties from the one you are working on and they have to oblige. Think they have 6 months to comply

 

[Gavin John Hyde]

You can ask the DNO to remove the supplies to the other properties from the one you are working on and they have to oblige. Think they have 6 months to comply

Interesting. So do the homeowners have to pay for this alteration? As i know the dno have a legal right of access across land when it comes to a lot of there stuff. And are likely to say its not unsafe and any changes are non eseential so must be paid for.
Around here its western power distribution and they charge for anything and everything.

 

[HandySparks]

You can ask the DNO to remove the supplies to the other properties from the one you are working on and they have to oblige. Think they have 6 months to comply

Really? Do you have a source for that info?
I can believe it if there's a supplier's fuse shared by two properties, but looped supplies are common round here.

 

[mhar]

No, it is at the DNOs expense. You may get paid for any alterations that are required to the meter tails (which they ask you to do).
I am in a WPD area and I have a job in a few weeks time where they are paying me to present new tails to a new cutout position and then get a decorator to box them in. About £300-350.
I have a meeting with a system planner next week as there is an overhead supply for three neighbours (looped) attached to my customer's property which we want gone. It will involve a new pole.

 

[mhar]

Really? Do you have a source for that info?
I can believe it if there's a supplier's fuse shared by two properties, but looped supplies are common round here.

The phrase used locally is 'telling us (DNO) to fXXX off a supply'!
I believe it comes under the ESQCR regs

 

[HandySparks]

The phrase used locally is 'telling us (DNO) to fXXX off a supply'!
I believe it comes under the ESQCR regs

Interesting. Would that apply to underground supplies?

 

[Gavin John Hyde]

All very interesting, im going to look into just what the esqcr actually say... might be useful in future...

 

[Lister1987]

Bit of thread necromancy for a Monday. Been looking at my service head and discovered it is a looped supply, could I determine the earthing arrange from that? Earth goes to the side of the cutout but not an external block attached to the side (making it TNC-S given the neutral and earth enter on the same cable....if I'm recalling my arrangements correctly)

Will find my other thread and pull the image over ?

 

[davesparks]

Neutral and earth can be in the same cable on both TNS and TNCS, it just depends whether they are the same conductor or two different conductors.

 

[Lister1987]

Neutral and earth can be in the same cable on both TNS and TNCS, it just depends whether they are the same conductor or two different conductors.

Easiest way to identify with a DNO call?

 

[littlespark]

Quite common round here too. Lots of 2 storey blocks of flats with a looped supply going in downstairs and then looped to the upstairs flat.
Found one in a semi detached property recently with the cable running under the floor and through the party wall.