3 core 25mm SWA, not new colours, can it be used for meter <-> cu

[Taylortwocities]

Past advice here recommended use of 3 core 25mm SWA

So we get the full story, please link to the "past advice"

 

[cjard]

//www.diynot.com/diy/threads/what-cable-can-i-use-in-this-scenario.430164/#post-3347295

RFLighting said 25mm SWA

I'm perfectly happy with "normal" meter tails (no swa) between meter and switched fuse.. sorry, should ahve been more clear.. The total distance from meter to CU is say 10m, so from past advice I'd need to do this as a sub main type of setup:

TNCS head -- 0.5m --> meter -- 0.5m -> switch fuse --- 9.5m --> cu

and the 9.5m part was going to be 25mm swa based on past advice.. Maybe 16mm would be acceptable. Maybe I should ask my spark who will wire it and sign it - it's not the DNO I have to assuage, it's him..

The cable that the DNO fitted (up to the service head) may not be 25mm; i'll check this evening. There is currently no meter(s) installed on the board, so the service head is where things stop. I thought the meter installer would go from service head to meter, (and from meter to switch fuse with "standard tails"? or is that my sparky's job?)
The cable from switch fuse leaves the meter board area, goes into a buried 100mm duct running alongside the foundations, and then pops up inside the house party wall. It must then run a further few meters in the cavity at the base of the party wall (a 50mm cavity between two 100mm block dwarf walls) to reach the understairs cupboard, at which point it leaves the cavity and appears through the wall of the timber frame panel and up into the CU. For the entire run it would be impossible to use a 50mm long drill bit to penetrate the wire in any place where it is not visible - this may or may not be relevant

 

[riveralt]

I thought the meter installer would go from service head to meter, (and from meter to switch fuse with "standard tails"? or is that my sparky's job?)

Everything up to and including the meter is the DNO's everything from the meter is down to you - with the caveat that you are not allowed to touch the meter itself.
Most DNO's will fit meter tails from the meter to a 100Amp isolation switch - if you ask them nicely.
Then your electrician will fit your meter tails from the isolation switch to the Switch Fuse and CU.
I heard that some DNO's will install cable from the meter to your Switch Fuse if provided.
Honestly it is best to speak to them and agree what will be provided by whom and at what cost.
If I read your comments right you intend to run the cable meter tails in a cavity wall? Don't think that is allowed.

 

[cjard]

If I read your comments right you intend to run the cable meter tails in a cavity wall? Don't think that is allowed.

Some misreading going on here I think.. I can't see myself having said that anywhere in my post above.

You seem to refer to a switch fuse and a 100a isolator as different things. Is the switch in a switch fuse not a 100a isolator? Are you saying I need two switches and one fuse in the circuit between my meter and my cu that is ten metres away?

For clarity, when I say meter tails, I mean the bits of wire that come out of the meter. They cease being meter tails at the first thing they come to after the meter. A 9.5 metre length of SWA between CU and (some kind of switch) is not a meter tail in my dictionary

 

[riveralt]

If I read your comments right you intend to run the cable meter tails in a cavity wall? Don't think that is allowed.

Some misreading going on here I think.. I can't see myself having said that anywhere in my post above.

This is the part I read....

The cable from switch fuse leaves the meter board area, goes into a buried 100mm duct running alongside the foundations, and then pops up inside the house party wall. It must then run a further few meters in the cavity at the base of the party wall (a 50mm cavity between two 100mm block dwarf walls) to reach the understairs cupboard, at which point it leaves the cavity ....

I cannot immediately quote you the regulation but it is frowned upon for any cable to run in the cavity wall. IMHO any cable that crosses a cavity wall should have some form of protection anyway - SWA may fit this.

[You seem to refer to a switch fuse and a 100a isolator as different things. Is the switch in a switch fuse not a 100a isolator? Are you saying I need two switches and one fuse in the circuit between my meter and my cu that is ten metres away?

They are different things. One has a fuse and seems to be a requirement by the DNO when the CU is more than 3 metres from the main fuse - whereas the isolator does not have a fuse but is often fitted by the DNO so that electricians can connect directly to the CU from the isolator without the need either (illegally) connecting directly to the meter or having to call the DNO out again when the connection to the main fuse is needed.
You have a picture already of the 100Amp fuse here is a 100A isolator that they use: http://www.fastlec.co.uk/wylex-100a...LonPGgAUua14jDeIXZ2XdyPVi-OR4wZOh0aAlxe8P8HAQ
I was raising the option for you to discuss with the DNO of you providing the fuse isolator and asking if that was okay for them to use rather than having to have both the isolator and the fuse isolator.

[For clarity, when I say meter tails, I mean the bits of wire that come out of the meter. They cease being meter tails at the first thing they come to after the meter. A 9.5 metre length of SWA between CU and (some kind of switch) is not a meter tail in my dictionary

They will still require some form of fuse protection if the distance between the meter and the CU is more than 3 metres.

 

[JohnW2]

You seem to refer to a switch fuse and a 100a isolator as different things. Is the switch in a switch fuse not a 100a isolator? Are you saying I need two switches and one fuse in the circuit between my meter and my cu that is ten metres away?

If I understand correctly Riveralt was indeed referring to two separate things - but I think probably mainly because of issues of practicality/convenience. Whilst the DNO (or meter operator) may well be prepared to connect the meter tails to an isolator switch, they may well not be prepared to connect them to a switch fuse. If that were the case, and you were going to have just a switch-fuse, then your electrician would have to be there at the same time as the DNO/MOP, or else the DNO would have to be called back when your electrician was there in order to disable the supply whilst the electrician connected the switch fuse.

Kind Regards, John

 

[cjard]

Hokay, so my next steps:

I thought the energy supplier (e.g. EON) installed the meter? Or will they tell my local DNO rep (XYZ company, working on behalf of ENWL) to install it?

I should call the energy supplier and arrange to have meters installed

I should call the DNO rep and ask him if he would be prepared to install to a 100A DP switch fuse (like this) only, or does it have to be a 100A isolator going into a 100A switch fuse

I should get whatever he wants, and leave them on site/screw them to the board ready for when the meter fitter turns up

I should ask the meter fitter if he would also kindly install the cables into the switch fuse/isolator that has already been screwed to the board, otherwise I should arrange for my spark to be there to do that part while the meter guy is there (or before, even - surely my spark could connect up whatever the DNO wants in terms of screwing an isolator/switchfuse to the board, and leaving dangling tails ready for the meter fitter to fit to the meter when he brings the meter)

 

[cjard]

If I read your comments right you intend to run the cable meter tails in a cavity wall? Don't think that is allowed.

Some misreading going on here I think.. I can't see myself having said that anywhere in my post above.

This is the part I read....

The cable from switch fuse leaves the meter board area, goes into a buried 100mm duct running alongside the foundations, and then pops up inside the house party wall. It must then run a further few meters in the cavity at the base of the party wall (a 50mm cavity between two 100mm block dwarf walls) to reach the understairs cupboard, at which point it leaves the cavity ....

I cannot immediately quote you the regulation but it is frowned upon for any cable to run in the cavity wall. IMHO any cable that crosses a cavity wall should have some form of protection anyway - SWA may fit this.

That part of the circuit wasn't what I was thinking of when I was referring to meter tails (which I think of as separate, single core copper wires leaving a meter and going somewhere, not in any armour), sorry for leaving it open to misinterpretation

Suffice to say, I have a timber framed party wall that at its base is 1 concrete block high. The buried duct from the meter pops up central to this and from there, sure I could either run the SWA in the cavity between the blocks, or at the base of the blocks on the inside of the house. My reason for not preferring the latter was that the floor has deep insulation and underfloor heating in it and this derates the cable to an excessive amount; the party wall cavity should be cooler, is well away from any potential source of damage and goes all the way to where I'd like the CU