How much kVA do I need?

[sam851]

I'm hoping somebody can help me.

Im converting a 4bedroom flat to 3 x 1bedroom flats.

I am having a new 3 phase supply installed for 3 the flats. UK Power Networks have asked me how much kVA will I be needing in total.

Each flat will have its own gas supply with the heating & hot water supplied from the boiler. The cookers will be all/mostly gas.

I understand the capacity for a 3 phase is about 70kVA, however the DNO has said that there is limited amount of space available on the network and if the full 70kVA is required they may need to pass my application to another department to price and install, which is considerably more expensive.

My question is how much kVA would I actually need for the 3 1 bedrooms flats?

 

[pc1966]

More a case of just being realistic to avoid an overcharge, I can't see them actually putting in under 80A to be fair. But operating at 60A just makes everything so much easier - 16mm tails etc etc

True, also you would get selectivity between a 100A DNO fuse and your 60A local one.

 

[sam851]

Thanks for replies. So i'm looking at saying somewhere 30-40kva to the UKPN.

Its actually my idea for the new 3 phase supply to the flats. I just want the ground floor shop and the flats to be as independent as possible to minimise future management of tenants of the shops and the flats.

Also would about a 3-4kva allowance be a reasonable amount for the communal entrance for the flats? There would be lighting (internal and external), a Grade A fire alarm system with control panel, some emergency lighting and a single socket.

The idea would be to fit a 4 way Ryefield board over the new 3 phase supply head so that I can split the power and connect 4 meters. From what I've found out this is he most correct way to do the split.

I may sell the units individually in the future, so I just want the flats to be correctly split.

 

[timhoward]

Just a comment that the form is horrendous and I have to think carefully and hard filling it out - get a sparks to look over the form before you hit send!

 

[Rockingit]

Thanks for replies. So i'm looking at saying somewhere 30-40kva to the UKPN.

Its actually my idea for the new 3 phase supply to the flats. I just want the ground floor shop and the flats to be as independent as possible to minimise future management of tenants of the shops and the flats.

Also would about a 3-4kva allowance be a reasonable amount for the communal entrance for the flats? There would be lighting (internal and external), a Grade A fire alarm system with control panel, some emergency lighting and a single socket.

The idea would be to fit a 4 way Ryefield board over the new 3 phase supply head so that I can split the power and connect 4 meters. From what I've found out this is he most correct way to do the split.

I may sell the units individually in the future, so I just want the flats to be correctly split.

You DEFINITELY need an experienced contractor to look after this for you, this is significantly beyond DIY research.

 

[sam851]

The work will definitely be done by a qualified electrician. But as I am in the planning stages I just want to get my head around how the major parts works. The entire conversion will be given to a building contractor to do, who will probably sub contract out the electrical work. I will be responsible for getting the new supply installed to save on costs, so as of now I don't have an electrician yet who I can call to get the answers.

The plan is to tell UKPN I need 40kVA on the new 3 phase supply. They install the new 3 phase supply with the cut out head. The fuses will either be 3 x 60A , 3 x 80A or 3 x 100A depending what UKPN decide to install. The electrician would then install a 3 phase 4 way Ryefield board straight above the cut out head. This will feed into the 4 meters, with an Isolator switch after each meter. The communal consumer unit will be in the same location. The consumer units for the flats will be inside each flat.

Can the cable thickness of the incoming 3 phase supply vary ? or is it a standard thickness?

Am I missing something in the above set up?