Day Night Electric Switches breakers

I am at home in Netherlands but plotting the next 4 weeks of renovation to our old farmhouse in The Chartreuse. But I have left my Everything about French Electrics book in France.

I was wondering how the jour/nuit disjoncteurs work for the hot water and heating system?
Seems you need a special breaker for the fuse box but do I need anything else in the fuse box e.g a timer and do ErDF have to give me a special account or dual meter.

Many thanks in advance for any advice


To operate a water heater via the HP/HC switching signal provided at the meter you require the following:
A maximum 20A disjoncteur for the actual water heater load circuit (which must be in 2,5mm² conductors).
A 2A disjoncteur to protect the switch circuit that runs from the main tableau to the meter & back (uses 1,5mm² conductors)
A “contacteur jour/nuit” to respond to the switch circuit & to do the actual power on/off of the water heater.

There’s a diagram here.

There is no need for a timer as the grid/meter does all that for you.

If you are using a heating programmer (such as a Delta Dlore Calybox) then the 1,5mm line to the meter is not used & instead you use the “téléinfo” contacts on the meter to run the programmer digitally via a screened cable. The water heater hardware works the same though.

More info about that here.

All the above only works if you have the right electricity account (heures creuses/heures pleines) & a “double tarif” meter, which used to be a different item in the days of mechanical meters but nowadays is just a question of having the digital meter reprogrammed. Your bills will say what you are subscribed to if you can’t work it out from your meter display.

Thanks Jonathon

Jonathan… :roll_eyes:

Oops apologies

Guys I read your posts with interest. We have this system with a Hagar contacteur which has three positions O - Auto - I.
Am I correct in assuming that the ‘Auto’ position is the one which switches on when the cheaper night rate becomes available? (I know it’s dangerous to assume anything with regard to anything French!)
Trouble is,I don’t have any instructions as to its use. We have a Tariff Bleu account with EDF.

Any assistance you can give would be great.


Yes that is the one we have for the hot water

see satached a screen dump from my excellent Electricite Par Soi Meme book

Thanks Andy. Since posting I’ve found that a wire linked to A2 on the contacteur has come loose. Now fixed… We’ll try tonight on Auto and see what happens. Fingers crossed. Cheers.

We have just bought our new house and I was wondering if anyone could explain how this day / night switch works - I have never seen one like this and also cannot find anything on it through a google search:


Hmm. Mine has a digital clock. It looks like you’re seeing the mechanical clock side on. Depending on the position things will go on and off. I only have the cumulus on it. Seems to be called an interrupteur horaire. At least I thought the arrow points to the current time but as they are different I’m probably wrong. Then depending on the blue buttons each circuit goes on and off.

why not ask the folk from whom you bought the property… ???

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Something like this?

I’ve a bunch of those on the power boards. Upstairs and downstairs water heaters, ditto bathrooms ufloor heating, ditto towel rails, etc. Originally they were digital programmable things with daily and weekly programmes which you needed a manual to program and reprogram every time there was a power outage. The Legrand ones are simple, tough and easy to programme. I didn’t realise they were that expensive though. I just thought the electrician who put them in for me was applying the taxe étranger :slightly_smiling_face:

We installed these for a couple of towel radiators:

Available elsewhere for less (got ours from Italy)

Taxe étranger :joy:

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