Fernicarry

Thanks. I suppose it depends on the PFC of the final circuit and the curve of the MCB. Isn't there also the same selectivity problem between the fuse in the cut-out and the one on my side? Or do they have different characteristics and if so what type should I be looking for on my side if I go with the option of fuse carriers in an enclosure?

I can imagine that wasn't cheap, anything for 3P seems to be silly money. But I'd be struggling for space to fit a switch box like that. Its an old house so I don't have a purpose built space for the cut out. Its currently in an upstairs bedroom in a fairly narrow boxed in cupboard and SPEN have agreed that they'll honour the existing dimensions in the new location at the front door. I'm making the new space quite high so that components can be stacked vertically if needed. Cut-out roughly half way up, go up to the meter, back down to the isolator alongside the cut-out and then out the bottom. Since I'm currently wired for single phase I think what I'll do is put a main switch and a single 100A MCB in a small metal enclosure and call that my "consumer unit". That way the 3m rule doesn't kick in. There should be enough space for a 4 or 6 way unit below the cut-out. I can revisit when I'm ready to start using the other 2 phases.

I'm having my cable head moved by SPEN and expect they're going to want an isolator and/or fuse since the consumer unit will be more than 3m away. Its a 3 phase supply but with only one phase metered at the moment. I currently have a fused isolator like one of these https://www.fusebox.shop/products/fusebox-fms080-80a-main-switch-fused. As part of the move I want to get everything ready for 3-phase for the glorious future of EV's and HP's. The new position is quite tight for space so I'm looking for a compact solution. Hoping to frame out the space this weekend if I can get a good idea of how much overall room I will need. I have a Wylex REC4 to provide the isolation part and if that's all they want then, great, job done. For the fused part I'm thinking of these options: - a REC3 with 3x 100A MCB's (as well as the REC4) -- but current breaking capacity of MCB's isn't as great as fuses, on the other hand they probably trip way faster so that gives discrimination with the fuse in the cable head, if there is a fault that an MCB can't clear then the cable head fuse will deal with it - modular fuse carriers like Lawson MS221 -- these are 2 modules wide so I'd need a compact 6 module enclosure for all 3 phases but I could live with only 2 available so potentially another REC4 enclosure would do Any other ideas?

So I've got my quote from SPEN to move my cut-out. They want me to provide ducting meeting ENATS 12-24 standard, 50mm ID, in red. Google is unable to find anything meeting this spec... There is class 3 twin-wall ducting OD63mm/ID50mm to EN 61386 but its not ENATS certified. And its black. Red seems to be more for HV cables. Any ideas?

The gods are smiling on me this week. SPEN called back to say that they will honour the size of the existing board at the new position.

Sorry for the confusion on the word "solum". I've always known it to mean the space below a suspended floor. In connection with land titles it means specifically the soil on which a building rests. Anyway, on to the next question. Part of the guidance is that the cut out can't be on an internal stud wall. Which this will be because its backing onto the front room. This seems to be in case of drilling into the wall from the other side and hitting the back of the equipment. You'd have to be going some to manage that though as it will be a good 5" below the surface from the other side of the wall. You can add a 1mm thick earthed steel plate to mitigate this, but I rather suspect if its all buttoned up and the back of the lath and plaster isn't visible then no one is going to question that it isn't on a masonry wall. Something I should be concerned about? I'm all out of 1mm steel plates at the moment....

I mean the crawl space under the ground floor.

Thanks for the replies. Yeah, even a large meter box has less board space than they want for an internal cut-out. I'll crack on wth my current plan and make a boxed in area at the front door as wide as I can. It will back onto the living room wall so I'll line it with cement board. Just for reference, can the cable duct run through the solum? The path of least resistance would be to route the duct into the solum at the closest point to the service cable.

19th century detached house with a 3ph cable head currently situated in an upstairs bedroom fed by a concentric cable that goes up the side of the house half way across the loft and then down through an internal partition wall into the bedroom. Not the ideal position. I've already moved the CU from there to a position towards the back of the house which puts it close to all the big cooking and washing loads. If anything the loading at the back of the house will only increase if/when we are forced to get a HP and EV. I'd like to move the cable head to the front door between the storm doors and the inner door. My (very long, but fused) meter tails from the current position to my new CU already run past there. Space is a bit limited because of the thickness of the stone wall at the front of the house. I can just about squeak 400mm in width, but there is plenty of height. Obviously this doesn't meet SPEN's requirements of 800 x 600 for the size of the board I need to provide for their equipment but looking at what's currently installed it looks perfectly possibly to fit it into this space. The current cut out is only 200mm wide and the meter can be mounted above it then come back down to an isolator switch and into my meter tails. SPEN called me the other day about the application and when I explained this situation she was quite literally dumbfounded about what to do. It seems like no one has ever been in my situation! I asked for a site visit but she said that the contractors who do the site visit wouldn't be able to advise about this "they only look at the cables".... She's supposed to investigate and call me back at some point. Anyone done something similar and can advise on how to persuade SPEN to be pragmatic about this? They haven't definitely said "no" yet, but I feel it coming. The new position is going to be far better than the existing position even if its not perfect. This house wasn't exactly designed wth 21st century rules in mind. Also is it permitted to run the ducting for the service cable across the solum or does it need to be buried under ground? If I could do that then I could route the service cable fairly directly to the back of the house and put a meter box on the outside wall a short hop away from the fuse box. If it has to go underground then that means excavating half way round the perimeter of the house doing battle with the gas main and the drains in the process. Thanks.