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Power supply rating
by dissid32 • Mon 02 Aug 2010 11:28

Thank you, Dave, for all the information on electrics. After reading your info and various posts, I still have a question, which perhaps you or someone else can answer.
My supply is 12kVa three phase. Making a quick calculation, I think I only need 6kVa. However, is it the case that if the demand isn't properly balanced across the three phases, or maybe just because it's spread across three phases, one needs a higher power rating than if it was single phase?
I think the reason I opted to remain on three phase was was in case I ever wanted to install an electric kiln, but I think that's probably unlikely to happen now. Would you advise getting it changed to single phase, and does that also entail getting the wiring changed at all?
I'm sorry if these are rather silly questions, but I'm very ignorant about electricity.
A final question: does anyone know if the phone number for english speaking help at edf is still 0562164908, and the email address still

Many thanks,

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Feb 2006
Re: Power supply rating
by Dave • Mon 02 Aug 2010 16:03

If you have a 12kW 440volt triphase supply, then you actually have three times 4kW 240 volt monophase supplies. Depending on how your house is wired, it can be that all the 240 volt circuits are wired into only one supply - thus it will trip at 4kW, which is pretty low.

EdF will change the triphase to a monophase supply if you ask them (the normal choice being 9kW) - this used to be free, but I expect that there is a standard 60€ charge now so you have to decided if it is worth it. Unless you need triphase then I would recommend that you ditch it. This shouldn't require a change to your wiring and will allow you access to cheaper tariffs.

If you think that you might use it later, then you can wire some circuits into each of the three supplies, say putting the cooker on one, water heater on another and lights and sockets on the third (or balance the loads as you need too). You should really consult an electrician about this because combining two live wires instead of one live and the neutral, will give you 440volts instead. Not something that you want to make a mistake about and also you will need separate protection for each supply so it makes the wiring a little more complex than it might be.

The all the English speaking numbers are listed here.

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Aug 2004
Re: Power supply rating
by dissid32 • Mon 02 Aug 2010 20:18

Thanks very much for the info, Dave. It's definitely not anything I'd dream of tackling myself.


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Feb 2006
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