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Electricity - how many kw?


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I'm having my supply changed from 3 to single phase.  I have a really old meter.

Question is... how do I know how many kw I have (not enough to run the washing machine and dishwasher at the same time, that I know!!!) .... there's no mention of it on my bills and I can't see anything except a 10.3a (amps?) stamp on my meter.

Any ideas where to look?  I need to work out how much, if any, I need to get it upgraded to?  I understand that once it's not three phase, I'll get more use of my current power and less tripping out.


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OK, here is what my electricity bills say (on the back, under "montant à régler")

Characteristiques de votre tariff:

Electricité; tarif domestique, option heures creuses; puissance 6kw

The puissance 6kw is the giveaway...

By the way 6kw is enough for us - it has only cut out one time when we had nearly all of our big appliances going. Got to make use of cheap time!


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I don't know exactly what EDF equpment you have installed, but apart from the meter you might have a black box which acts as the main disconnect.  It has a small red button to act a trip test and a larger black button to reset.  Mine has a small grey cover (sealed by the EDF) through which you can see the current rating of the main fuse, 45 amps in my case.  I believe the alternatives are 30 and 60 amps.

Alternatively, if you look on the back of your last EDF bill, down at the bottom, it might say something like "Electricite, tarif domestique ..... puissance 9 kW" or whatever your own rating is.

Hope this helps.

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I think there are a few things to consider here and you may find you are better off sticking with 3ph so I wouldn't jump until you fully understand all the implications.

In the simplest of terms the main reason 3ph is used in domestic environments is to improve the distances which can be achieved without having to install transformers everywhere. The load is shared over 3 smaller circuits instead of one big one allowing for the use of smaller, and therefore cheaper and lighter, cables.

If you are at the end of a long line then you could find that by going 1ph you could have an unacceptable voltage drop. In theory I see no reason why it would not be possible for EDF to aggregate the 3 cables into one to negate this problem but I don't know if they would do this or not.

Don't forget also that you will have to rewire your house so it would be something of a "no going back" change !

As for tripping, before just blaming the 3ph and comitting to the change you should find out exactly why this is happening. It may be a simple case of having too many items plugged into one of the 3 phases. Remember when your house was first electrified power gobbling appliances such as washing machines and electric cookers etc. weren't in common use so whilst those sockets in your kitchen or utility room might seem nice and convenient it might be that a huge proportion of your overall load is on one phase and it's that imbalance which is causing it.

If you have got an imbalace it could be hitting youy in the pocket too because the meter may be clocking up at the highest load of the 3 phases.

You really need to do your homework and even perhaps get a professional in to advise you. 


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The house is about to be rewired fully anyway (currently everything is going through two plugs and extension leads!... enough I know to trip things out).

However, I've heard that it's very difficult to get 3 phase properly balanced and one can often have a lot of problems with this.

I also understand that it can be incredibly dangerous.  Electiricity is always potentially dangerous of course, but my understanding is that one false move with 3 phase and it can all be over, rather than just a nasty shock.

We will evenutally have three buildings (a year or two down the line) so in theory/practice is it possible to have a phase for each building and would this be the best option.  Equally, I don't want to end up paying three sets of standing orders if I can possibly avoid it.

Does anybody else have 3 phase, and have found it useful for domestic use?

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If you're having a rewire then probably a good idea to go for it. I guess EDF will tell you if your lines are insufficient to support 1ph and what your options are.

3ph can indeed be difficult to balance because, apart from anything else, loads are not constant.

It can be very dangerous too as you have 440v between phases which is obviously potentially far more lethal then 220v or 240v.

Good luck in getting away with NOT having 3x standing orders for 3 separate buildings with 1ph supplies [:-))]

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I guess EDF will tell you if your lines are insufficient to support 1ph


I have just helped out a friend who wanted to do the same thing, simply by acting as translator between him and EDF. The cost that they quoted for the change of  3 phase to single phase was 140-00 euros.  This is the EDF cost if they own the lines to the house. However, before you can do that you need to get them to survey the 3 phase lines because in many instance the lines are owned by the commune and if you wish to change then you will have to pay the commune.  Needless to say he chose not to have the 4000 euro addition for the change of wires that the commune wanted. Instead he chose to get a electrician to balance the system by ensuring that each phase shared the major loading items and that each phase had its own differential circuit breaker for safety. Hope that helps

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I think there seems to be some confusion about three phase supplies..............

Unless you have three phase motors or specialist equipment that needs three phase , there is absolutely NO BENEFIT to the end user( ie; you the customer) of having a three supply supply into your house. In fact you are at an immediate disadvantage.

Three phase supplies are usually to benefit the EDF so that their distribution network stays balanced . This is especially important in rural areas where the end user may ne quite some distance from the nearest pole mouted or roadside transformer, and the voltage drops for the EDF would result in problems for them.

Let me explain why you are disadvantaged by having three phase; Here are two main reasons .

If you have a 9KW single phase supply, you can draw a little over 9KW from this supply before the EDF disj will trip. Whereby if you have a 9KW three phase supply your electrical installation has to be wired and balanced over the three phases and this means that if you draw a little more then 3KW over any one of the three phases your EDF disj will trip. Believe me this is one of the major disadvantages and it is quite difficult to manage this balancing effectively, without clever use of circuitry and controls.

Reason two is quite simple - The voltage levels are much higher 380/400 volts between any two phases and this can be very dangerous to have in a domestic situation. Many DIY installers simply do not realise how much danger they are placing their loved ones in when attempting to work on such installations.

The EDF will often dictate whether this is possible to convert to single phase - usual maximum on single phase is 12KW.

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