Surface mount SWA through the bin cupboard area, then a small(ish) metal box, above, below or to the side of the CU to terminate the swa into, then into the CU?

Switch fuse isolator in the meter box will, usually, satisy the DNO, but it doesnt satisfy 7671, as the cables will need to be RCD protected if buried/hidden. The worst solution, but one that will satisfy the DNO and 7671(just/maybe) is to put an isolator in there (has it already got one?) with a 30mA RCD as the isolator switch. Of course, that could trip if anything else down the line trips, so not a good solution.

I'd be looking at a way to get SWA in there. It isnt the DNOs box, it is yours, and so long as they can get access to their equipment, there should never be a problem.

Downrate the fuse. (1) I am surprised that the DNO has not done that already. (2) Just how much power are you going to draw? At most we have an 80 A fuse, but it may be 60 A - I forget. In any event, if I ever finish the new supply, it will be on a 63 A MCB.

Strictly, 4 m tails are a bit long, but I don't quite see the problem. Would you cut off the first metre or the last?

Any bends if you use conduit?

Thanks alanblaby 

I'll admit to having not thought about the RCD option. The person who fitted the new meter (a third party contractor) threw me a bone and fitted a switch in there so that I didn't need to pull the master fuse to make the changes. So an RCD could go in there but as you say it's not a nice option and you couldn't uses a selective type to prevent duplicate trips. Thus meaning it isn't a 7671 compliant option because it doesn't provide isolation of faults from adjacent or downstream circuits.

I considered the box option to terminate SWA next to the board, but concluded it didn't help: As the problem remains the same the SWA is entering the room through the wall the box will be mounted to. Thus making the termination problematic. I suppose one advantage, upon reconsidering the situation, is that at least in the future the board can be removed without disturbing the SWA meaning I don't need to leave slack.

A final thing that I should have mentioned but didn't is that I'd like to leave the space for current clamps in the future as I'll almost certainly be fitting Solar PV + storage which will need them as do some EV chargers. Again the second box option makes these a lot easier.

--Edit--

I believe you're half right on the putting things in the meter box. Yes it's my property but as part of the supply contract you have to guarantee not only access by the DNO but space for any equipment they deem necessary and those boxes are an agreed size, and should be left to them by all accounts I've ever seen. Hence I'm twitchy. But I could, I suppose, loose / replace the switch and call it quits.

Hi Chris Pearson 

Thanks

Like you I was surprised i wasn't just given a 60A fuse. But it was a third party did the work and I suspect he didn't have one on the van / wasn't authorised to make changes like that. But I am glad they didn't. Why...

Because over the next couple of years I'm going to ditch the gas (for multiple practical and personal reasons) and I'll be fitting EV charging. The combination means that 60+ amps will be perfectly possible. Having just done the paperwork for a mates EV charger I can vouch DNO's want to know if you're fitting them to a property with a 60A main fuse.

I've never seen a supply with its own dedicated MCB before but that's probably just my lack of knowledge / experience. what are you hoping to achieve that the master fuse doesn't dare I ask?

Yes there would be a single right angle bend. My plan would have been to put an inspection box in at that point and use that to make the earth connection. That said I suspect the bend would have been tight.

So one thing that's been going through my head.

Is there any reason I couldn't use BSP pipe as opposed to steel conduit? it's made to a BS standard after all....

I ask as the BS standard for conduit appears to have specifications for 38 and 50mm but nobody stocks them. However, 1 1/4 BSP is easy to get hold of and is thicker walled due to the courser thread pitch. So I don't see why it couldn't be used. I'll have a single bend so putting in a draw string will be easy, and a long radius bend will be well above the minimum radius I'll need to make the corner at the top of the vertical.

I can vouch DNO's want to know if you're fitting them to a property with a 60A main fuse.

I've a feeling they want to know even if you had a 100A fuse - as the increase in demand adds to the transformer load and the demand on the street mains.

1 that I have no way of terminating the SWA in the meter box without invading the DNO's space

Official answer to that is to install a separate enclosure next to the meter box - ordinary & slimline meter boxes are readily available. That gives you plenty of room for termination and a switchfuse (and exposed tails before the switchfuse for any current clamps).

So I can see this option needing me to bring the SWA in from above or below the board which would be ugly as sin in my hallway,

Can t be re-routed so be straight up/down where visible and then covered using maxi trunking? Or re-position the CU?

- Andy.

1 Gas pipe

Someone will pop up and say that black or galvenised  iron gas pipe is made to the wrong BS. of course.
(This stuff.. )

That is true but not  really relevant, there  is plenty of imperial conduits about and no one asks about that. The hard part may be  getting a good earth contact to a malleble iron pipe of non-standard diameter, but it should be possible to mis-use a plumbing fitting or to drill a hole for a nut and bolt  (or even tapped hole )  in a way that does not obstruct the cables.

https://www.bes.co.uk/flanged-hexagon-backnut-brass-11-2-6549/  going into a box perhaps

The exact impedance of  gas pipe may be unclear so you may want an additioinal CPC to assuage the doubters.
The other thing you will need are the right pipe threading dies and a decent pipe bender, but those could be  hire items unless you know a tame gas fitter type. And bending a 1.1/2 iron pipe will test your muscles  and may benfit from hydraulic assistance.

2 SWA - ideas

Or if it helps with SWA, remember one can terminate the armour in a gland on a metal box or plate in the ceiling and carry the inner as a rather wilful multi core "flex" into a further enclousure.
Arguable the inner 'bedding' that holds the cores together is not really insulation, and so the "peeled" SWA should be inside something like plastic trunking, rather than run any distance exposed to touch,  but it is a lot tougher than broken out into singles straight away. Leaving very  long tails allows them to be led into the CU in a less ugly way for termination.

M

Thanks Andy

1: Absolutely agree that DNOs and to know in every case. there's an ENA form for that exact purpose, but the route through the form is different if you've got a 60A master fuse and the EV point has to be limited to no more than 30% of the maximum demand.

2 Yes I could add another box on the front of my house to house all of this but would you want to do so to yours? I suppose I could loose it on the inside of the wall where the meter box is located but the bin store has been lined with SuperLux (i suspect because the tails ran through it) and is thus not exactly structural. It's quite hard to explain and I realise I'm throwing back curve balls to every suggestion thus for so sorry. 

3 Yes I could bring it in from above or below but as I've said the SWA will enter the room via the wall the board is mounted to and thus it'll need to bend through 90 deg. As it'll likely be 25 - 30mm in diameter it'll have a bend radius of 150 - 200m would you really want a large black cable poking that far out from the wall just inside your front door? Hence the only option I really see is to enter from the rear of the enclosure and loose the termination in the wall itself.

Relocating the board has to remain an option, and as it's been washed a couple of times by a leaking hot water tank I'm not too precious about the hall ceiling but it does feel A bit extreme at this point.

If you can get into the bin cupboard from the meter box run standard 25mm tails (and a 16mm earth as the existing on is probably 10mm) into the bin cupboard and fit a switch fuse in there. Then carry on in standard 25mm tails through the wall to the CU.  Presuming i am reading your description properly.  Use a bit of galv or plastic 2x2 or 3x3 trunking to tidy the cables up.  No rcd required on the tails. 

35mm tails is  OTT

Gary

I could bring it in from above or below but as I've said the SWA will enter the room via the wall the board is mounted to and thus it'll need to bend through 90 deg. As it'll likely be 25 - 30mm in diameter it'll have a bend radius of 150 - 200m would you really want a large black cable poking that far out from the wall just inside your front door?

I'm not sure of your exact geometry, but the cable doesn't necessarily need to go through the wall at 90 degrees (i.e. horizontal) - say it was a 45 degrees to vertical you'd only then need a 45 degree bend inside which protrudes a lot less (possibly enough to stay within say 50x50 trunking) - angles closer to vertical improve the situation further (if needing a longer SDS bit...). Or if you've got a bit more patience and a bit of skill with a cold chisel, you could curve the inside of the hole to match your chosen bend radius so the cable arrives neatly vertical on the inside.

   - Andy.