Meter siteing and cable routing

[David E]

We are converting a barn and the new supply will be installed by the REC sometime in the next couple of months, but we are wanting to think about where the CU will be and where cables can run.

Are there any regs about routing the supply into a building? It makes sense to have the meter box in an external wall and the best wall would be approx 2" timber clad on the outside, the original 6" block in the middle and a 4" plasterboarded timber frame as the inner skin. If my memory serves me right a meter box is 8" deep so remove a few blocks and put a lintel in and bobs your uncle.

If this is the case can the SWA supply be be taken up the wall behind the timber cladding into the meter box or does it need to be clipped externally and so be visible?

Finally siting of the CU, sensible it should be central to the barn, but if so is there a restriction to the length of (suitibly sized) tails that can be run from the meter to the CU and can they be routed in the loft space or through a stud wall as long as it is within a safe zone? Alternativly if the meter be inside the barn are there any regs regarding the running of SWA through the barn or would the same rules as the tails apply?


Hope this makes sense

 

[plugwash]

We are converting a barn and the new supply will be installed by the REC sometime in the next couple of months, but we are wanting to think about where the CU will be and where cables can run.

sounds sensible

Are there any regs about routing the supply into a building? It makes sense to have the meter box in an external wall and the best wall would be approx 2" timber clad on the outside, the original 6" block in the middle and a 4" plasterboarded timber frame as the inner skin. If my memory serves me right a meter box is 8" deep so remove a few blocks and put a lintel in and bobs your uncle.

If this is the case can the SWA supply be be taken up the wall behind the timber cladding into the meter box or does it need to be clipped externally and so be visible?

you'll have to ask the rec, anything before the meter is their concern not yours btw it probablly won't be swa. the recs preffer concentric.

Finally siting of the CU, sensible it should be central to the barn, but if so is there a restriction to the length of (suitibly sized) tails that can be run from the meter to the CU and can they be routed in the loft space or through a stud wall as long as it is within a safe zone? Alternativly if the meter be inside the barn are there any regs regarding the running of SWA through the barn or would the same rules as the tails apply?

well the recs won't usually let you have more than a couple of meters of cable past the meter without your own overcurrent protection. also many don't feel comfortable using un-armoured cable for long runs with such a high rating.

there are also volt drop issues to be considered.

is this barn a huge place or something?

 

[JohnD]

When I worked for Eastern Electricity* (as was) we had a safety bulletin round one day. Someone had been nailing a flower basket to the side of the house (one of those covered in a soft Suffolk Pink render) and gone through the incoming cable (before the meter and fuse).

It seemed this house had an overhead supply, which had been brought down the side of the house and rendered over.

There was a stern instruction that supply cables up to the service head had to be on the surface of walls where you could see them. I don't think that hiding it behind timber cladding would be good. One day someone will be nailing a loose plank up...




*not as an electrician

There are other rules about cables hidden inside walls that have already been covered in other posts., but the incoming supply and the tails are the worst ones to put a nail into, I believe the results can be quite spectacular as well as much more dangerous than a fused final circuit.

If you have an underground supply it's very easy to put a cable duct into the concrete under the floor, which is much less likely to be damaged, then a short run on the surface of the wall to the meter.

 

[David E]

Sorry I know what the concentric cable looks like but assumed (wrongly) that it was lumped in with the title "SWA"

Regarding the routing of the supply, the cladding wont be fitted prior to the installatin of the supply cable so if the hole for the meter box was made and fitted with a 2" batten between the edge of the box and the 6" blockwork to give the overall 8"s required, when we clad the wall "over" the cable would the fact that there was a meter box vertically above the line of the cable run be sufficient to designate the area horozontally to the left and right and vertically above and below as a "safe zone" or is this a dangerous presumption to make?

The barn is not huge and probably 4m of tails would be sufficient to carry on up the wall from the meter box horozontally someway to the middle of the barn and vertically down to the CU. Regarding overcurrent protection, I seem to remember that the REC wont allow anything that is not "theirs" in the meter box so presumably we would need to make provision for an overcurrent protection somewher close to the meter?

 

[JohnD]

?couldn't you arrange for the meter box and the CU to be close together? say, on the outside/inside of the same wall?

 

[David E]

Possibly, but looking at the plans the best place for the CU was in a cupboard in the hall which is actually closest to the front side of the barn where we don't want a meter box.

If it is a daft idea to do what we first thought of well the CU will have to be in a bedroom.

 

[JohnD]

I can see bedroom wouldn't be convenient. No chance of a passageway? Is the front door site unsuitable on appearance grounds? Maybe a panel with the cladding could be fitted over the meter cabinet to blend it in?

 

[David E]

Back to the drawing board then!!!!!!

 

[plugwash]

got a rough plan of this place?

you can get IP rated modular boxes (e.g. http://www.tlc-direct.co.uk/Images/Products/size_3/MK5702.JPG). could fit one of those just above the meter box with a 63A DP breaker (http://www.tlc-direct.co.uk/Products/CM9863B.html) in it and then run 16mm T&E or split con from there to the CU.

 

[JohnD]

neat idea. Looks like it could be used as a "main switch" is that right? Will 63A be enough, or is this to give discrimination with the service fuse?

 

[Lectrician]

Assuming as your title says cornwall, your DNO is Western Power? Wester Power allow any length meter tails you like - they will connect to anything

They will also put the hockey stick duct in the wall - it is actually you that fits the box and duct. Aslong as they can pull their cable in easily, you could loose the hockey stick in the wall.

All these things are things you can discuss when the DNO come to look and quote, assuming they don't just give you their standard connection charge.

 

[Qedelec]

Personally, when it comes to cable protection, I would cover the incoming cable with a 2mm steel plate, and if possible earthed back to the MET.

 

[David E]

Makes sense and not difficult to do if put in when the wall is clad

 

[Adam_151]

What about 60/80/100A switchfuse (as appropiate) and SWA/split con (or appriopiate size) from that to the postion of the the CU?

 

[plugwash]

a modular box with a 63A dp mcb is smaller than most switchfuses, availible in a IP rated form and doesn't require replacement fuses.