wozza Posted February 24, 2019 Share Posted February 24, 2019 Hi All, Our current consumer unit (also the solar inverter) is in the garage , which will soon be converted to a bedroom, so SWMBO has asked if the consumer unit and the solar inverter can be moved into the utility. No problems with the inverter as its just a couple of cables, but the CU would be around 8 meters from its current location. I have not spoken to the electrician yet but wanted to try and understand what it involves / requires before I do so that I am better armed when I do. I have a few questions, and as I have only a basic knowledge that I have gained from reading threads here and the tinternet, so please feel free to correct me. 1, If moving the CU more than 3 meters from the meter then I need protection for the cable, which would be better, a fused switch or a RCD? (it will be housed in the external meter cupboard) or is either fine? 2, Some of the existing cables will probably not reach the new location and they cant be replaced, what would be the best way to join them (Wagos in a box, Junction boxes? something else?) 3, I was thinking of getting a High Integrity CU so that "Mission Critical" (not my term) appliances such as the alarm, smoke alarm, freezer etc would go on their own RCBOs with everything else split across dual RCDs. (I have read that some people put smoke alarms etc on the same circuit as lights so you would easily find out if the rcd has tripped, but I have had bulbs blow before that have tripped the RCD) - Any thoughts on this and what mission critical items to have on the RCBOs 4, Any recommendations or brands to avoid for the consumer unit etc (currently liking a Wylex NMX High Integrity Unit) 5, Apart from the height, does the CU need any considerations, for where it is mounted? Please feel free to add anything that I have missed, Thanks, Wozza. Link to comment Share on other sites More sharing options...
dpmiller Posted February 24, 2019 Share Posted February 24, 2019 what kind of supply/ earthing do you have? 1 Link to comment Share on other sites More sharing options...
wozza Posted February 24, 2019 Author Share Posted February 24, 2019 Standard 240v mains supply. Earthing I believe is 6mm, it was replaced a few years ago. Link to comment Share on other sites More sharing options...
Onoff Posted February 24, 2019 Share Posted February 24, 2019 He means TT, TN-S or TN-C-S earthing. 1 Link to comment Share on other sites More sharing options...
wozza Posted February 24, 2019 Author Share Posted February 24, 2019 Sorry its a TN CS (Marked up as P.M.E) Link to comment Share on other sites More sharing options...
ProDave Posted February 25, 2019 Share Posted February 25, 2019 There are 2 parts to this. Firstly you need an electrician to move the consumer unit, which almost certainly means replace it with a new one in the process. There will usually be a lot of cables to re route so don't underestimate the amount of work and disruption to the building., Then you need to get the DNO to move the supply head to the new location. The cost for that will not be cheap, and again there is the disruption to the building to get the new supply cable in to the new location. A half way house is leave the supply head where it is and feed via a switch fuse to the new consumer unit, but if the object is to get all the stuff out of the garage then that does not really achieve that. 1 Link to comment Share on other sites More sharing options...
wozza Posted February 25, 2019 Author Share Posted February 25, 2019 2 hours ago, ProDave said: There are 2 parts to this. Firstly you need an electrician to move the consumer unit, which almost certainly means replace it with a new one in the process. There will usually be a lot of cables to re route so don't underestimate the amount of work and disruption to the building., Then you need to get the DNO to move the supply head to the new location. The cost for that will not be cheap, and again there is the disruption to the building to get the new supply cable in to the new location. A half way house is leave the supply head where it is and feed via a switch fuse to the new consumer unit, but if the object is to get all the stuff out of the garage then that does not really achieve that. Thanks Dave. just to clarify, It will definitely be an electrician who does the work, and the disruption is inevitable as we are extending upwards and converting the garage to a bedroom. The supply / meter box is on the outside wall, it feeds through a hole into the garage and up to the CU in the garage - the cables then go off inside the garage roof space in various directions to feed the house. The extension is going above the garage and also converting the garage to a ground floor bedroom, so the plan is to move the CU along the wall by about 8 meters, the cables to supply the house from it will then be in between the floors. Link to comment Share on other sites More sharing options...
Ferdinand Posted February 25, 2019 Share Posted February 25, 2019 The only points I would make are 1 - Have a master off switch inserted on the supply side of your CU, such that it can be worked on more safely and you can switch everything off should you need. 2 - Think carefully about future expansion possibilities. The extra cost will not be that much. Though you are perhaps doing both anyway. F 1 Link to comment Share on other sites More sharing options...
ProDave Posted February 25, 2019 Share Posted February 25, 2019 Okay if you are happy to keep the meter in it's box on the outside wall, you do not have to move it, You can keep it there, and your electrician can run a new submain via a switch fuse to the new consumer unit location. My previous comment was made on the assumption the meter was on the wall inside the garage. That new submain will have to be something like steel wire armoured cable to avoid the need for having to rcd protect that run. 1 Link to comment Share on other sites More sharing options...
Carrerahill Posted February 25, 2019 Share Posted February 25, 2019 (edited) 1 hour ago, wozza said: Thanks Dave. just to clarify, It will definitely be an electrician who does the work, and the disruption is inevitable as we are extending upwards and converting the garage to a bedroom. The supply / meter box is on the outside wall, it feeds through a hole into the garage and up to the CU in the garage - the cables then go off inside the garage roof space in various directions to feed the house. The extension is going above the garage and also converting the garage to a ground floor bedroom, so the plan is to move the CU along the wall by about 8 meters, the cables to supply the house from it will then be in between the floors. OK - this is not difficult in terms of what needs to be done, but may prove difficult in execution depending on age of your house and the way it is wired. If it was me, and I was doing this in my property or indeed specifying how these works were to be done, I would first create a new sub-main, so from meter tails, into a 100A switchfuse at the meter end, then out on a new cable to another isolator (so you can isolate whole CU locally) before your CU. The sub-main cable would ideally be a appropriately sized split concentric cable (LSZH - low smoke zero halogen is best for internal use like this), probably a 16mm² or 25mm² (depends on your supply rating) or SWA (they end up bigger overall diameter) - however, you could use T&E or even meter tails in conduit - with all cable options except split you really need to have a separate 16mm earth cable - check your split concentric spec, it should have 16mm² on 25mm². You cannot rely on steel armouring for your earth. Depending on route and protection you would really need to protect the whole sub-main with an RCD which is not ideal so I would look into a suitable route and almost certainly use split concentric - that is what the DNO would run. Then to the final circuits, ideally I would want to pull in new cables from the first and last socket on each ring and new feeds to the lighting, cooker, shower radials, this way you do not end up with a junction box to extend all the cables back to your new CU - that is just messy and can impact circuit suitability. Edited February 25, 2019 by Carrerahill 1 Link to comment Share on other sites More sharing options...
wozza Posted February 25, 2019 Author Share Posted February 25, 2019 Thanks to everyone for your great replies and advice Could anyone advise on suitable master switches? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted February 25, 2019 Share Posted February 25, 2019 I fitted one of these: https://www.tlc-direct.co.uk/Products/CGMSF100.html with an 80 A fuse, so if there is a major fault that fuse will (hopefully) blow before the 100 A DNO fuse (I hope it never does!). 1 Link to comment Share on other sites More sharing options...
wozza Posted February 25, 2019 Author Share Posted February 25, 2019 So, just looked at the Main Fuse at the meter and its marked up as 100A and also as 80Amp by a sticker (See the Pic) We did have a new meter a few years back so I am assuming that they changed the 100A fuse for an 80A fuse. So should I ask the electrician to fit a 80A fuse or 60A fuse in the new switch? Link to comment Share on other sites More sharing options...
ProDave Posted February 25, 2019 Share Posted February 25, 2019 Get him to asses your likely total load. 60A will probably be quite adequate unless you have some seriously big loads. 1 Link to comment Share on other sites More sharing options...
Markblox Posted February 25, 2019 Share Posted February 25, 2019 I don't think it's been mentioned but if installing a new CU all the existing circuits will have to be tested, therefore you can expect the electrician to be all over the house taking reading as well as a lot of testing of the circuits at the new CU location. A new cert will have to be issued and the work is under part P regs. 1 Link to comment Share on other sites More sharing options...
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