Meter tails though cavity wall

[Ronknights]

Hi Everyone,

Having an extension built, and had to move the incoming electrical supply. It will be 4m from the consumer unit. Am told by EDF I need a switch fuse within 2m from the meter, which is no probs. Plan is to have tails from the outside box, up the cavity wall inside to a switch fuse in corner of the hall just under ceiling height, then tails above plasterboard in ceiling (running though middle of joists) to consumer unit 2m away.

My questions are...

Can theswitch fuse be in the meter box instead of the house? There is plenty of space!

Can I run meter tails inside the new cavity wall?

Will the insulation in the wall de-rate the tails?

Can I use 25mm tails from the switch fuse to the consumer unit?

Do the tails have to be in conduit? plastic or metal?

Thanks all in advance!

 

[ColJack]

1. put the switch fuse in the meter cabinet
2. I wouldn't..
3. yes It would..
4 & 5. run 25mm 3 core SWA or split-con to the CU location... no need for conduit then...

 

[holmslaw]

..

 

[Ronknights]

Thanks ColJack - I already have plenty of tails and conduit so is that acceptable to use instead getting SWA?
Holmslaw - thanks, but do you have any suggestions on a better method?

 

[Lectrician]

1. put the switch fuse in the meter cabinet
2. I wouldn't..
3. yes It would..
4 & 5. run 25mm 3 core SWA or split-con to the CU location... no need for conduit then...

Umm....

1. You cannot put any of your kit in the DNO's meter box. You can place a second meter box adjacent to the first if you wish.

2. It is permissible to run meter tails in the cavity. This is both an exception in BS7671 and the NHBC guide. It is commonly done on nearly all new builds and renovations. Due care needs to be taken when installing obviously.

3. Depends on the insulation. If it the polestyrene type sheet attached to the inner skin then it has long been accepted that the tails still have plenty of room in the cavity, and them touching the covering of this sheeting is fine. If it is cavity fill you should take precautions, however, take a look at an 80amp fuse vers 25mm tails in BS7671, you may be surprised.

4. You could run tails with an earth if run in close proximity to each other (cable tied together, bunched or clipped adjacent). Nothing wrong with that. Split con may be easier. SWA is laughable these days, especially for two meters through a loft or floor void (actually, especially a floor void where you need drill joists). 25mm SWA may well also be overkill if you are using a 60amp sw fuse. An 80amp would require 25mm, and 100amp would be pointless. No conduit required for the tails.

1, 2, 3, 4 and 5. Can you not simply put the consumer unit where the switch would be? It is not that much different in size, and actually would look smarter.

 

[RF Lighting]

Very diffficult to understand your post, but from what I have gleaned most of what you propose is unacceptable.

I really don't know why you bother to come to this site with such pointless, unconstructive drivel.

Why not try offering a bit of constuctive criticism, or heaven forbid, a bit of advice for once, instead of wasting everybody else's time.

 

[ColJack]

1. put the switch fuse in the meter cabinet
2. I wouldn't..
3. yes It would..
4 & 5. run 25mm 3 core SWA or split-con to the CU location... no need for conduit then...

Umm....

1. You cannot put any of your kit in the DNO's meter box. You can place a second meter box adjacent to the first if you wish.

If I pay for it and install it.. it's MY box and I'll put what I bloody well like in it.. they require you to provide the box round here.. I've also seen CU's in the meter box so a switch fuse shouldn't be a problem.. plenty of room..

 

[RF Lighting]

Unfortunatly, it doesn't work like that.

Many DNOs will not be bothered about a switch fuse in there, especially if you use something like an MEM KMF800, but they would be within their rights to not allow anything at all in there.

 

[Lectrician]

1. put the switch fuse in the meter cabinet
2. I wouldn't..
3. yes It would..
4 & 5. run 25mm 3 core SWA or split-con to the CU location... no need for conduit then...

Umm....

1. You cannot put any of your kit in the DNO's meter box. You can place a second meter box adjacent to the first if you wish.

If I pay for it and install it.. it's MY box and I'll put what I bloody well like in it.. the require you to provide the box round here.. I've also seen CU's in the meter box so a switch fuse shouldn't be a problem.. plenty of room..

Still not correct as per your contract with the provision, and who is to say where the OP is based? He may not be in your area.

You may advise him to do as you do, and the DNO turn up, refuse to connect, and tell him to remove his kit. The extra cost of him then moving his stuff, adding a second meter box afterwards, and then the revisit fromthe DNO and metering company would cost a fair bit. Simply by following your incorrect advice.

 

[ColJack]

if they want to dictate what goes in there, then they can bloody well pay for it..
it's a cheek I tell you.. they'll be expectig us to pay for the cable and joint kits next.. and to buy the cutout and meter off them..

 

[Ronknights]

Thanks Lectrician. The insulation is cavity fill, what sort of precautions do you recommend? Running the tails in some kind of duct or large conduit so there is plenty of air around the cable?
I was thinking of moving the CU position, it will mean extending or re routing lots of cables - the switch fuse option would be less work!
I don't have a copy of the regs - what is meant by looking at an 80amp fuse vers 25mm tails in BS7671?

 

[ColJack]

25mm "tails" clipped direct = 114A
25mm "tails" enclosed in a conduit on a wall or in trunking etc = 101A
25mm "tails" enclosed in a conduit IN a thermally insulating wall etc = 80A