Scoobyrex Posted May 25, 2021 Share Posted May 25, 2021 Obviously this will be done by an electrician but would like to have a good idea on an approach so I do not get over engineered or over charged by Electricians doing the work. I have a bunch of questions. We hit a bit of a curve ball on the service plot we have bought with that the 125mm duct in the new road it seems doesnt exist as per the drawings.... looks like the new road is getting dug up. So assuming that gets sorted we will have a 3 Phase connection to a GRP meter cupboard at the edge of the plot. First is to sort out a temporary supply for the build. Assuming 3 phase supply and a 3 phase meter in the GRP kiosk. The build only needs a single phase. Can a single phase consumer unit be hooked up to a 3 phase meter, or do I need a small 3 phase distribution board right from the off ? the CU/DB will go into a surface mount meterbox on the side of the site office (Shed) along with a couple of double sockets. Once the build is finished a 3phase SWA cable will be used to connect the GRP kiosk to the dedicated plant room in the house, and we have the following needs(big power wise) 3P 16KW 3 Phase ASHP 3 Phase Car Charger. (Maybe two in the future) 10KW 3Phase Solar 1P 32A Hot Tub 3x 16A garden heaters Double Oven Steam Oven Plate Warmer 2 x Dishwashers 2 x MHVR units Tumble Dryer Washing Machine. Large electric fire in living room. My thinking is something like this. A medium size 3 phase distribution board, (12 way ?) for all the 3 phase MCB's 3 x single phase consumer units. and spread the load. unit 1, Washing Machine, 1 oven, 1 dishwasher and upstairs sockets and lights Unit 2, tumble dryer, 2nd oven, 2nd dishwasher and downstairs lights and sockets Unit 3, Hot Tub, Outdoor lights. garden heaters, indoor fire. The reason for doing this I can use 3 pre-populated schneider single phase consumer units, for a much lower cost than a large 3-phase distribution board with extension units considering the cost of the MCB/RCBO (1P or 3P) in the 3P distribution board. Space in the plant room isn't really an issue. am I missing something ? or making this way more complicated than it needs to be ? Link to comment Share on other sites More sharing options...
JFDIY Posted May 25, 2021 Share Posted May 25, 2021 (edited) 1 hour ago, Scoobyrex said: Can a single phase consumer unit be hooked up to a 3 phase meter, or do I need a small 3 phase distribution board right from the off ? Yes, Just get the power provider to install a three phase meter to a cut-out isolator, your electrician can then run normal 'tails' from one phase, neutral and earth into a standard single phase consumer unit to get you running for now. Careful trying to mix phases in the dwelling, you really need something like 6ft separation if memory serves, so putting your appliances across more than one phase in a kitchen could be tricky. I believe the reason for the separation is do that you can't get a 415v shock, but that either needs two concurrent faults, or someone meddling who shouldn't be. Edited May 25, 2021 by JFDIY Link to comment Share on other sites More sharing options...
TonyT Posted May 25, 2021 Share Posted May 25, 2021 There is no regulation about proximity of different phases in close proximity to each other. personally I would go for a 3 phase board it’s what is done in the industry. Link to comment Share on other sites More sharing options...
Scoobyrex Posted May 25, 2021 Author Share Posted May 25, 2021 Just seems somewhat overkill as I would need a large 3 phase distribution board and probably an extender, filled mostly with single phase MCBO's The single phase MCBO.s RCD's ect for 3P units are significantly more expensive than compared to their 1P brethren. Link to comment Share on other sites More sharing options...
TonyT Posted May 25, 2021 Share Posted May 25, 2021 (edited) The single phase mcb/rcbos that fit a single phase board fit a 3 phase board manufacturers don’t mix them about... you wouldn’t need an extender you get large 3 phase boards. it’s a more elegant designed solution in my opinion. Edited May 25, 2021 by TonyT Link to comment Share on other sites More sharing options...
Scoobyrex Posted May 26, 2021 Author Share Posted May 26, 2021 16 hours ago, TonyT said: The single phase mcb/rcbos that fit a single phase board fit a 3 phase board manufacturers don’t mix them about... you wouldn’t need an extender you get large 3 phase boards. it’s a more elegant designed solution in my opinion. ahh ok, I was looking at the schneider range, I didn't realize the single phase MCB's/rcbo's would be interchangeable between easy 9 single phase CU and KQ 3 phase boards. Is it straight forward to assign what phase the each mcb/rcbo is connected to ? Link to comment Share on other sites More sharing options...
JFDIY Posted May 26, 2021 Share Posted May 26, 2021 Don't think they are, I've got a KQ board in my garage and should you be brave enough you can live swap breakers in and out. The easy 9 doesn't have the extra lugs/contacts to allow this Link to comment Share on other sites More sharing options...
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