Hi, I'm converting a house into 2x2bed flats and have to split the electrics (upgrading from a phase 1 to phase 3). The EDF form asks for my KVA requirement and research I've done suggests 23kva 100a. Can anyone suggest what would be a suitbale value. This is for standard domestic use. Thanks alot for your help.
23,000 Watts? For two flats? Are you really sure about your calculations?
When you say upgrade from phase 1 to phase 3, do you mean you want a 3 Phase supply to both flats because you are installing large workshop machinery and things?
On Tue, 6 Jan 2009 05:53:47 -0800 (PST) someone who may be sun snipped-for-privacy@hotmail.co.uk wrote this:-
"Upgrading" from single phase to three phase? If so, why?
Without having seen the house, or being given details of it, any answer you get here is worth what you pay for it. However, for most of the two bedroomed flats I have seen 100A each would have been excessive.
My guess is that you could simply have them split the existing supply to provide two meters. There is probably no need to change the existing supply arrangements other than to split at the building, though as you didn't mention what they supply arrangements are this cannot be stated firmly.
Unless the building is being totally rewired, segregating the internal circuits may be a rather more interesting task.
Do you mean you currently have a single phase supply, and you have been told you need three phases for two dwellings (I'm /sure/ that is wrong)?
Or do you mean that you currently have a supply from one of the phases, and you have been told you need to use a different phase for the other dwelling?
The reason I ask is that "phase 3" is not a commonly used term (whereas "three phase" is).
A 100A supply (which is what 23kVA means) sounds generous for a flat, but not impossibly so.
Ah, I meant 3 phase, and EDF say they provide "up to 3 phase 100 amp (70kva). and 4 domestic properties no more than 43 meters from a passing main" EDF want to know what the curret KVA is (surely they would know already) and my required KVA for new dwelling.
Isn't the 23kVA the total rating of the 3phase supply? i.e. 7.66kVA or
33.3A on each phase. That's not a lot and would easily fit onto a single domestic supply nowadays. How about keeping the original supply & metering and splitting it via two new meters, one for each flat. They are cheap enough now. It would be way cheaper than having a 3phase supply installed.
No, they wouldn't necessarily, it's why they're asking.
The first question to ask yourself is what type of heating you're installing, as electric heating - and particularly storage radiators - get switched on all at the same time, thus allowing for no "diversity" i.e. if you have 3 radiators in each flat, each pulling
3kW, and for the sake of easy maths 1kW=4A then you need to have a cable coming in that's big enough to take all that load at once.
So... 3 * 3 * 4 = 36A for the storage rads alone, then factor in if you're going to use off-peak water heating etc.
Alternatively, and it's getting to be common, consider panel heaters - they're effectively a simple electric element / convector heater, but the load will switch in and out as the rooms get to temperature, therefore you can apply diversity to the total "possible" load. This means you don't need to add the full rated load of the heaters to be used at any one time, you apply a scaling factor.
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