Building over a live cable supply

[lakelandfolk]

Hi,

We have plans in to upgrade the energy efficiency of our house and to build a single storey extension. Our local electricity company has written to planning pointing out that the extension will be on top of the supply to the house meter. They do not appear to be saying we can not build the extension. Does any one know the regulations re building over live cables. Do we have to re route it?

If we were to build a meter kiosk then a sub main cable to the house would we have issues taking that cable through the house to the consumer which is on the far side?

By the way, a conservatory, which will be removed to make way for the extension, was approved by planning in 1993 and is built over the same cable.

[Jeremy Harris]

Provided the supply cable is at a safe depth (your DNO will let you know their preferred or mandated depths, they vary a bit from one region to another it seems) then there's no real problem.  Our supply cable runs right under our slab, for example.

 

The main issues are making sure the cable is protected during building work, and that the builder/ground worker understands the risks.  Our ground work company had to uncover a fairly big (95mm²) three phase cable that feeds several houses further up the lane, and which ran right across our plot.  They carefully dug it out and lifted it to the surface, until the DNO came along to re-lay it in ducts the ground works guys had laid around the edge of the site.

 

It might be a good idea to think about relocating the meter and putting a duct in under the new extension for your supply cable.  Not essential, but it would add a bit of future-proofing if there was ever a problem with that cable, and it would also mean that the cable under the new extension was yours, rather than the DNOs, which in itself could make life easier in future.

Edited April 21, 2017 by JSHarris

[ProDave]

I think I would want to know more about the type, age and condition of the cable.  Worst case scenario is the cable fails after the extension is built, and you have to somehow get a replacement in.

 

It might well be worth getting a quote from the DNO to at least replace the cable with new, and route the new cable in a duct so in future a replacement could be pulled through, or even better re route it around where the extension is going.

[Nickfromwales]

On 21 April 2017 at 17:28, ProDave said:

 

It might well be worth getting a quote from the DNO to at least replace the cable with new, and route the new cable in a duct so in future a replacement could be pulled through, or even better re route it around where the extension is going.

+ 1000. May not be as expensive as you think either. The older cables are a nightmare. If moved or struck then you'll get an even bigger bill. Remember you can do the contestable work yourself . 

[Temp]

Most houses end up built over the supply cable... at least the bit where it comes up into the meter cabinet :-)

 

Just a matter of protecting the cable where it goes through the foundations. Use a cable locator and hand dig to find it. 

 

If we were to build a meter kiosk then a sub main cable to the house would we have issues taking that cable through the house to the consumer which is on the far side?

 

Shouldn't really be necessary. I believe it would have to be at least 50mm deep if chased into walls or provided with protection. Fuse and switch needed in the meter cabinet but that's not usually a problem.

[Steptoe]

Personally if it were me, I'd price having the DNO move the whole meter etc to an outside position, as said above, also allows for future proofing.