New Supply 3 Phase to 3 x Single Phase

[scoobybacon]

Hi

I have a site currently without power, had the distribution company visit and they can run in either a single phase or 3 phase supply. if I went with the 3 phase supply, then to a 3 phase meter and then to a board that would split the 3 phase to 3 separate single phases, one for each building - would that all be viable?

just not clear on splitting the 3 phase - is it easy to do? what sort of board would you need?

I would put everything in an external cabinet by building one, supply building one from that cabinet, and then run two single phase supplies to building 2 and 3 with their own distribution board

I understand single phase but 3 phase has me a bit stumped on how easy it would be to do

how big a cabinet would I need - the guy couldn't really inform me how much space for the feed, meter I would need - I can then factor in anything I add

I will be using a pro - just need to get my head round it - been searching but not clear

TIA

 

[Murdochcat]

This is seriously not a diy job …. One slip and you’ll very brown bread

 

[scoobybacon]

This is seriously not a diy job …. One slip and you’ll very brown bread

100% but I am just trying to understand it and be more informed

 

[Murdochcat]

The best advice I can give you is find a local spark.

Just bear in mind that the metering is best kept separate

 

[JohnW2]

Just bear in mind that the metering is best kept separate

Do you mean a separate meter for each phase?

If so, that's obviously what one wants/needs if the phases are supplying buildings or parts of building which under separate occupancy, but if all are being used by the same person/family, three separate meters will usually mean three Standing Charges.

 

[Jurassicspark]

but if all are being used by the same person/family, three separate meters will usually mean three Standing Charges.

Not always...

 

[JohnW2]

Not always...

Maybe "not always" but, as I wrote, "usually".

 

[Murdochcat]

Do you mean a separate meter for each phase?

If so, that's obviously what one wants/needs if the phases are supplying buildings or parts of building which under separate occupancy, but if all are being used by the same person/family, three separate meters will usually mean three Standing Charges.

Might be. The OP hasn’t given enough information as an over view as to what they are trying to achieve …….

 

[flameport]

how big a cabinet would I need

This or the equivalent from other manufacturers: https://www.meterboxes.co.uk/products/mitras-3-phase-recessed-electricity-meter-box
It's substantially larger than the single phase versions.

You MUST confirm the specification required and the location before ordering the new supply.
It you get it wrong, then no electricity for you.

I would put everything in an external cabinet by building one, supply building one from that cabinet, and then run two single phase supplies to building 2 and 3 with their own distribution board

Meter boxes are for the supply and meter only.
Anything else will need it's own enclosure, or normally would be located inside the building.

 

[scoobybacon]

I would be happy with 1 meter - main thing is suppling the 3 buildings with a suitable 240v single phase supply suitable for say a small domestic house size - I expect the load to be a lot less in each building but just as a rough indication - and whether that can be achieved sensibly and if the best option is 3 phase in, to 3 single phase supplies - and if there is a smart solution in terms of a distribution board or similar that can go in the main cabinet

 

[JohnW2]

Might be. The OP hasn’t given enough information as an over view as to what they are trying to achieve …….

Agreed. I was just outlining the pros and cons dependent whether the three buildings were under separate or the same ownership.

Although my experience is limited, I can't say I've ever come across a '3-phase supply' with three separate meters. If separate phases are taken to different building, or different parts of a building, then I think that virtually all supplies would regard that as "3 (single-phase) supplies", each with their own account, Standing Charge and bill

 

[JohnW2]

I would be happy with 1 meter - main thing is suppling the 3 buildings with a suitable 240v single phase supply suitable for say a small domestic house size - I expect the load to be a lot less in each building but just as a rough indication - and whether that can be achieved sensibly and if the best option is 3 phase in, to 3 single phase supplies - and if there is a smart solution in terms of a distribution board or similar that can go in the main cabinet

As far as DNOs and suppliers are concerned, there really is little, if any, difference between "a 3-phase supply" and three separate single-phase ones, other than the metering, charging and billing.

What you are proposing is not all that unusual. In my house, I have a '3-phase supply' (just one 'account') with a 3-phase meter (and a single Standing Charge, which is the same as it would be for a single-phase supply), but use the three phases separately, as 'single-phase supplies' , roughly one for each floor of the house.

Kind Regards, John

 

[scoobybacon]

As far as DNOs and suppliers are concerned, there really is little, if any, difference between "a 3-phase supply" and three separate single-phase ones, other than the metering, charging and billing.

What you are proposing is not all that unusual. In my house, I have a '3-phase supply' (just one 'account') with a 3-phase meter (and a single Standing Charge, which is the same as it would be for a single-phase supply), but use the three phases separately, as 'single-phase supplies' , roughly one for each floor of the house.

Kind Regards, John

awesome - thank you - and do you just split that using one distribution board near the meter ? that's the bit I can not get my head round , 4 wires from the meter into what giving me 3 single phase outputs ?

 

[Adam_151]

You'll need some sort of switchgear, but as always there is more than one way to skin a cat. Cheapest way would probably be a bog standard type B TPN Board, however you'll be limited to 63A per supply and you'll have to cope with the lack of discrimination between MCBs. Or you could upgrade to an MCCB panelboard, but costs go up as well, you could have three single phase switchfuses and a load of henley blocks, but that may not be the neatest solution for a new install, very few would go down the switchfuses and busbar chamber route these days, too expensive and time consuming compared to other solutions. One slightly old skool solution would be a three phase switchfuse with ample room on the neutral block (Often see it done with EXELs or whatever the Bill equivelent was) and just take your three outgoing feeds off that, you don't get the ability to isolate them individually very easily/without disruption to the others, but often thats tollerable (best stick with ones with individal removeable carriers, rather than have to unbolt them from a carriage to take out individualy - Exels rather than glasgows etc)

 

[JohnW2]

awesome - thank you - and do you just split that using one distribution board near the meter ? that's the bit I can not get my head round , 4 wires from the meter into what giving me 3 single phase outputs ?

No. The ground floor DB is fed directly by one of the phases. The other two phases go via switch-fuses and 'distribution circuits' to other DBs on the upper two floors. If there is a significant distance from meter to any of the buildings you would have to do the same - but, like me, may be able to feed one DB directly (if its close to the meter).

Kind Regards, John