Supply in converted house

[b33k34]

Again, just looking for views here.

Converted Victorian house. 2 flats. Main supply comes in to two meters and switches in the shared hallway. From those (fused) switches the supply runs to CU's within the individual flats

Electrician is suggesting that need to:
- replace the switched fuse box (will check but could be wire wound fuse as C 20year old)
- replace the run from that box to the CU with 16mm armoured cable.

Is the armoured cable really necessary? The cable run is up from the meter into the ceiling then along for 4m in a 4" gap between the last joist and the solid wall, then up in a trunking in a cupboard to the CU.

 

[ricicle]

The electrician is the one who will have to sign the certificate for design, so what is said on here won't make any difference as we won't be.

 

[b33k34]

Fair enough. I'd still like a view on it. If the answer was along the lines of "that's very unusual and over the top" for a job that's probably going to add a few £100 to the bill then I'll think about finding another sparks.

 

[seasickstevie]

Not unusual at all to use SWA in that situation. In fact perfectly standard practice.

Having said that, nothing to stop you asking another spark's opinion anyway.

You haven't told us what the existing supply to the flat is like. And a photo would help.

 

[b33k34]

Current cable is a big fat white insulated multi-core cable. I've not had anything open to judge the cable size but it's probably from a 20 year old installation where the electrics generally seem to have been done to a fairly high standard.

I know that's not a lot of help. I'm fine to let him go with this one.

Thanks

 

[SimonH2]

I'm not an electrician, but I have a flat with a supply arrangement similar to what you describe.

Fuses at the supply end of the submain is (AFAICT) normal. Apart form anything else, they don't suffer from nuisance tripping when there's a fault which can trip multiple upstream MCBs.

In my flat, it's only T&E, which is perfectly fine if installed to have sufficient protection. From the description you give, that seems OK as well.

One thing is not clear, I take it the cables from switch/fuses to CUs are separate cables ?

As I read it, I find myself asking "why does your electrician say it needs changing ?" That would probably be the best place to start. He may be right, he may be mistaken, he may be making work for himself - hard to tell without knowing what his reasons are.

 

[SimonH2]

Oh yes, my flat is about 16 to 18 year old. I find it hard to imagine that something indoors has deteriorated so much that it needs replacing, and I don't think the regs in that area have changed half as much as they have inside the flat.

 

[b33k34]

Oh yes, my flat is about 16 to 18 year old. I find it hard to imagine that something indoors has deteriorated so much that it needs replacing, and I don't think the regs in that area have changed half as much as they have inside the flat.

Effectively it's inside the flat (upstairs flat and it's running along the edge of the living room wall). Hard to see how anything done in the house could ever damage it.

 

[OwainDIYer]

If the cable isn't armoured, it would now probably need RCD protection. That would be, in effect, one RCD for the whole installation, which is now non-compliant. And it may need replacing anyway if it's an inadequate size so has to be replaced to current regulations.

If it's adequately sized however there may be no call for replacing it.

4m of armoured ins't really that expensive though. 3 core 25mm is £8.60 per metre plus VAT at TLC.

 

[SimonH2]

If the cable isn't armoured, it would now probably need RCD protection.

Doesn't sound like it as I read the description of how it's installed.

In any case, if that part of the installation is not being altered, I didn't think the regs were retrospective.