Three phase in a new house?

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F Flinstone
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Three phase in a new house?

Post by F Flinstone » Sat Nov 03, 2018 12:12 pm

Is it possible? When the house is finished I want a nice workshop, some of the better quality machines are three phase, I dont want to go into changing motors or using converters, so I thought about having the house connected to three phase just for the workshop, the supply is at a new box on the corner of the land, so apart from two extra wires what difference is there in the house and is there a large cost to pay for meters, and standing charge, price of the electricity etc. Thanks Ff

lindal1000
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Re: Three phase in a new house?

Post by lindal1000 » Sat Nov 03, 2018 1:36 pm

Our house is 3 phase and it's a new build.. 12kva and 9kva 3 phase costs the same as single phase and the electricity is the same price.

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Mike
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Re: Three phase in a new house?

Post by Mike » Sat Nov 03, 2018 1:55 pm

The only problem you may have in the house is balancing the load over the three phase's, you will probably only have 20amps/phase which can be a problem with a double oven or induction hob, but most of them have the facility to have two of the phase's connected to them, use the third phase for the oven, but ensure its below 20amp.

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RobertArthur
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Re: Three phase in a new house?

Post by RobertArthur » Sat Nov 03, 2018 9:37 pm

Is it possible? Yes.

Conversion charges: see the ENEDIS pricelist, page 23, case #5, changing meter and disjoncteur de branchement + conversion from monophasé to triphasé = 156.25 € TTC

Supply on the corner of the land: if it is a so called branchement long you'll have to pay the new wiring from there to your tableau électrique.

Work to do: inside your distribution box. Distributing the L1, L2 and L3 between existing single phase circuits and trying to balance the loading of these three phases. To prevent tripping of the disjoncteur de branchement. Because your once generous overload limit of 45 amps in single phase (9 kVA supply) changes to 15 amps per phase in three-phase (9 kVA). To be on the safe side upgrade to a puissance souscrite of 15 kVA in three-phase, each phase with a nominal overload threshold of 25 amps. Or try 12 kVA, 20 amps overload per phase.

Work to do: add a triphasé RCD + disjoncteurs in your distribution box to feed the three-phase machines. Example. Or a three-phase tableau secondaire / divisionnaire in the workshop. This one is probably an overkill, but gives you an idea how the wiring has to be installed. From 2008 onwards such a second distribution box is considered to be a member of the circuit specialisé family, so feeding only from the tableau électrique principal.

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Re: Three phase in a new house?

Post by crakpot » Sat Nov 03, 2018 11:10 pm

I think you are mad 3 phase is old hat and the suppliers are trying to get rid of it in domestic homes

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Re: Three phase in a new house?

Post by lindal1000 » Sun Nov 04, 2018 9:20 am

crakpot wrote:
Sat Nov 03, 2018 11:10 pm
I think you are mad 3 phase is old hat and the suppliers are trying to get rid of it in domestic homes
Not round our way..especially when you consider that the maximum supply you can have on single phase is 12 kw..whereas on 3 phase you can have 18+. We run an air source heat pump, oven, induction hob, water heater, swimming pool plus usual appliances and all of OH's workshop tools off 12kw 3 phase. The only piece of equipment that doesn't like it is the very old welder, which when used on the highest setting, tripped out the phase. But as we have only needed to use it once in 7 years it isn't so much of a problem. I tripped out a phase once when we had the aircon, hob, washing machine, microwave / convection oven all on, and then I tried to boil the kettle! Other than that, no problems.

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Re: Three phase in a new house?

Post by F Flinstone » Sun Nov 04, 2018 9:33 am

crakpot wrote:
Sat Nov 03, 2018 11:10 pm
I think you are mad 3 phase is old hat and the suppliers are trying to get rid of it in domestic homes
If you care to re-read my opening you will see that Iam most certainly not mad :mrgreen: yet! The cost wise between single and three dosn't seem too bad, considering its a new house it should only be a small amount for the option of buying better machines, will get the architect involved and see what extra it is. Thanks RA as said there is nothing there yet, so nothing to change. Thanks. Ff

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Re: Three phase in a new house?

Post by RobertArthur » Sun Nov 04, 2018 10:18 am

Ff, a minor detail for the architect/electrician involved in the design: if the connection to the local grid is a so called "branchement long" it might be useful to wire in a separate switch cable (only 1.5 mm² or 2.5 mm²) from the EDF box outside to the house. To have the option of a day/night tariff (option heures pleines/creuses). To be used or not. Cable pulling afterwards (second thoughts) is not easy, pre-planning saves costs in this case. About a thing called GTL: many introductions available, this one follows the regs almost step by step, pages 28-39 in this Hager document. To conclude some thoughts on single and three-phase design. Caveat: this article has been published before the Amendement 5 changes (November 27th 2015).

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