# Electricity meters

36 kw? Shower, electric under floor heating, electric water heaters, welder, fridge, freezer, tv, washing machine… lights, ??? Will a 36 kw supply do? What do others out there have? Tell me your experiences.

You don’t have much choice - 36kVA is pretty much all you can get short of having 3 phase installed.

Electric showers aren’t as popular here - yes you can buy them but they’re not going to be a UK 10kW job.

The simple answer is you work to what you have - 36kV is fine/plenty until you start adding showers/boilers into the mix. Most people manage to have electric water heaters so… but

the experience of folk I know who have done either new-builds or revamp…

the electrician tots up what you intend to use by way of equipment… then tells you what you need by way of Supply.

I think 36kva (30kw ish) is only available as 3 phase, and maximum single phase is 15, or maybe 18kw.

I think that there may be a confusion of terminology here between Kilowatts (Kw) and kVA.
Perhaps this table will help;

Meter Power Rating 3 kVA 6 kVA 9 kVA 12 kVA
Intensity (A) 15 30 45 60

Many people in France manage adequately with the 30 amp (6kVA) supply compared to the standard 100 amp supply found in the UK.
The maximum power rating available in France on Monophase is 90 amps (18kVA) which will give a maximum power usage at any one time of roughly 19,800 watts (220 volts x 90 amps).

So all one needs to do is to add up the rated wattage of all the appliances that you may wish to use at the same time, and then divide that number by the volts (normally around 220) and you have the number of Amps that you need.
So if you want to be able to use say 16,500 watts (16.5 kilowatts) at the same time, then you will need a 75 Amp supply which to use the French term would be 15kVA.

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Maybe there is regional variation but we had a huge battle to get 18kVA supply as single phase. We were told quite clearly that the max was now 12kVA and 18kVA single phase was no longer allowed. Which wouldn’t work for us as we have air source heat pump in gîte and thermodynamique hot water in house plus all the other normal bits and bobs needed for both households. We got there in the end, but it was stressful!

So the lesson we learnt from that was to check what could be supplied to the house before buying a single phase air source heat pump and assuming that we could get the single phase supply we needed!

It is quite possible there is house-to-house variation depending on the details of your supply cable.

Robert’s table is correct, though the nominal voltage in France is 230v (ref.) - in fact the EU specification is 230 volts +10% - 6% (i.e. 216.2V - 253V). The “harmonisation” of mains voltages was chosen so that nations who’s distribution network was nominally 220V or 240V did not have to change anything to be “in spec”. Actually the range quoted has little to do with supply per se - it is the voltage range over which any electrical item has to work to fit in with EU Normes.

Why only max 12/15kVA monophase in France? (the following has a good bit of guesswork).

All electrical cable has resistance and pulling current through a cable will cause a voltage drop to be generated (per Ohms law).

This is a problem for the supplier for a number of reasons- for one thing it wastes energy for which they can’t charge the customer (a cable with 0.3Ω resistance carrying 60A is dropping 18V and wasting just over a kW of power), it heats the cable (and if the cable is in a confined space this risks fire) and the voltage drop might mean that a supply which starts out fine at 230V at the transformer will be out of spec by the time it gets to the consumer.

In the UK supply is normally on 25mm2 cable - looking at the limits generally in force in France (as well as the cable to our house) I suspect that (especially rural) France mostly uses 16mm2 cable for the overhead drop wire.

16mm2 cable has a resistance of 2.8 milli Ω per metre - so a 100m run will have a resistance of 2 x 100 x .0028 or 0.56ohms - pull 60A through that and it will drop 33.6V so, if your voltage starts out at the transformer as 230V, it will be out of spec by the time it reaches your house.

This can be compensated for by having a slightly higher voltage at the transformer but you can’t go too high otherwise the off-load voltage will go up and might go out of spec at the upper end of the permissible voltage range.

So, 16mm2 cable is good for 12kVA up to maybe 75m from the (usually pole mounted) transformer - after that they might go to 25mm2 which has a lower resistance (about 1.9 milli Ω per metre) and so is probably good to 120m, 35mm2 out to 150m and so on.

I haven’t worked in the electrical supply industry so I’m guessing a lot based on things like the permissible voltage drops and cable resistance - if anyone does have the details or a reference I’d be interested to get the details.

However i can quite see that EDF would say “oui” to one house for 15kVA, or even 18kVA monophase but “non” to a house a few doors down and further from the transformer (or require the cabling to be changed at the consumer’s expense) or “non” to a particular property but “oui” to one a little further away, but with heavier cable supplying it.

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That was a very clear and easy to understand explanation, thanks Paul. My house manages perfectly well on a 6 kVA supply but that is my only concern about the Linky meter that I am supposed to be having fitted sometime soon, I have a feeling that I might have to increase the supply to 9 kVA as they are less ‘flexible’ to surges above the limit than the traditional systems.

I think you have it right. Overall the maximum single phases supply is now 12kVA I believe. We got an EDF person out to discuss our situation, and the fact that we are just metres from big transformer box managed to change his mind (perhaps helped by a large application of flattery and charm over a cup of coffee and biscuits). So we have 18kVA and just have fingers crossed that they won’t one day rule this as no longer acceptable.

I think you sums are for copper cable, whereas all of ENEDIS’s local supply cables are now aluminium, with the exception of the final link in a Type 1 installation which is carried out with a special hybride coax; 25mm² aluminium core, with copper outer sheath, equivalent to 16mm².
Local overhead low voltage lines are all carried out in 4 x single 35mm² aluminium conductors as a twisted bundle.
As already stated; 12kVA (60A) is now the maximum monophasé supply allowed, but those who have old 18kVA (90A) supplies cannot have them taken away.
36kVA (3 x 60A triphasé) is the maximum supply available under “tarif bleu”/puissance limitée i.e. a supply that is physically limited by the supplier’s main breaker.

Yes the resistance figures are for copper from the linked reference (though looking again I think that already takes account of 2-conducters per cable so I might be out by a factor of two - the principle holds though) - I had a feeling aluminium would figure somewhere - it’s quite attractive for distribution networks being much lighter and cheaper than copper.

The design tolerence of your new Linky should be the same as the old disjoncteur de branchement i.e. you should have no fear about losing your supply due to the new Linky being somehow different. There are stories from the earlier phase of Linky deployment of supplies tripping too easily. This may have been true in some cases but was generally caused by people who had lived with tired old breakers that were bit too generous in their behaviour.
Once you have the Linky & can consult the app you will be able to see your maximum demand in any 24 hour period, & at what time it occurred. This will give you a clue as to how close you are to your limit & could allow you to plan to mitigate it.

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