Connecting HC appliance to auto contactor with Linky meter

I am in a quandary and do not know if it needs to bring in a professional or not, so hope I can get some help here first. From past reading, I understand there to be some well clued up folk on the subject and hope I can scrounge an answer please!

I have two hot water tanks, each wired with an auto HP/HC set up for the pre Linky meters, with a switched 2A supply going to the EDF contactor , then with EDF allowing the power to pass to A1 on my auto switch during HC hours and A2 of the switch going to return.

We only received the Linky last year, and on the advice from someone I was chatting to, I disconnected the circuit to the EDF contactor and taped the 2A MCB switch off. I cannot remember the actual reason for doing this, but it sounded good at the time…

I have been a bit lazy this last year and not re-connected the HC. So I thought I would give it a go this afternoon)

But rather than connect it all up as it was before, I thought I would test it out and make sure that the two wires going down the pipes originally to the EDF contactor, still functioned as before by checking them for continuity during the day and again tonight and then assume all was working well and re-hook the 2A supply.

I am glad I did, as I got a surprise this afternoon, as one set of the contactor wires showed 239V AC and the other set 100V but decreasing.

  1. I was surprised to see 239V on two wires that are - or at least were connected to a dumb contactor.
  2. I was puzzled as to why there was voltage though at 16:00 in the afternoon - but maybe the network decided this a good time for a short freebie…(?)
  3. The second set of wires to the same original contactor, I surmised are disconnected and the 100V is residual.

This triggered me remembering the reason for being advised to disconnect my pre-Linky HC wires, he said was something about Linky supplying the power for my auto contactor rather than I supplying it - ie that Linky has done away with the old EDF contactor and has its own switch that powers the auto, and that the Linky installer will have changed the wires from the old EDF contactor. Is this the case? And if so, can I strip out my existing 2A supply and have the two original contactor wires go straight to A1 and A2 of the auto contactor switch in the tableau?

Help appreciated and thanks,


No. There is no difference in the way that a Linky controls an HC/HP contactor - it is exactly the same as all previous meters. All the Linky does is close a dry contact during HC periods.

The live output of your 2A supply goes to C1 in the Linky. Once switched it returns via C2 to A1 on your contactor. A2 is connected to the neutral side of the 2A disjoncteur.

Without more info I can’t comment on the voltages you are reading, but they could be ghost readings, especially as the control wires will run parallel to the mains run.


Thanks Badger - really kind and useful!

Yes, the voltage readings are ghost (apologies my last post using ‘residual’ - it was meant to read ‘induced’) and looking in detail, the Linky installer has it exactly as you describe. I still cannot remember the detail of the advice I was given to disconnect prior to installation - but he was Canadian so maybe it is different over there… :smiling_face:

I am looking at my new contract from Engie, trying to work out if I am better off with HP/HC or moving onto a single price. Impossible to calculate! At 20c and 16c, maybe just as well continue (be thankful I am not in UK is what I say… :stuck_out_tongue:) and use the facility to the full and start by moving the pool pump to HC for a start.

I have in the past incorrectly used the EDF contactor for two different appliances using the traditional method. I have a warning note on the fuse box that this is the case, so will take the opportunity now to put the other tank and now the pump onto HC, but use a time clock so that there is no rogue power running around the fusebox without control - may I impose on your knowledge again? What are good bomb-proof single DIN 24h timers - there are many - cheap Chinese up to Hager at 95€! Are mechanical ones better than electronic? LeGrand have a mechanical one at 57€, but is it just a cheaper Chinesse one re-badged…?

Again, thanks

Whilst this is sensible there’s no need to involve additional timers as I imagine that your pool setup already has it’s own timer(s) in place.

Don’t forget that many appliances here in France have a delayed start feature so you can set them to operate during the 8 hour HP period. You may need to box clever & stagger the timings to avoid the whole load being on at once & taking your supply out.

Regarding your second water heater; I’ve often run two tanks via one 2A control circuit. Ideally the tanks & control circuit should share the same overall différentiel, but that is not obligatory, which is handy when you need to split water heaters across different phases in a triphasé installation.

Time switches: mechanical are cheaper but usually lose track of the real time in the event of a power cut, although some have a reserve battery to keep them on track. I’ve no particular favourite but tned to buy Legrand.

the whole of our new house (new electric installation) is fitted with LeGrand - excellent quality and reliability :+1:

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D’ugh to the pool pump - of course it has its own clock! Just changed it now, so tonight I shall start saving 36c per day… :slightly_smiling_face:

I should have mentioned that the second water tank is in a granny flat that has its own fuse box teed off the house from the hot side of its main switch. Yes I am not happy about it, but will put the remote one on a timer. Probably will use a Legrand one to match the rest of the fuse ‘tableau’


When we moved back to EDF we changed to the flat fee, I think eeve saved a few Euros / month however we are going over to Tempo in a week and hope to make dome good savings.

Thread drift alert.

Presumably you mean the main isolator in the main tableau? It would not be possible to connect to the live (hot) side of ENEDIS’s main breaker as that is sealed.

As you probably already know a “tableau divisionnaire” must have it’s own isolation in the board that it departs from i.e. you having it wired to the the live side of of another isolator is not on.

If the remote board contains it’s own 30mA différentiel(s) then the supply from the main board should not be run via any upstream 30mA device, nor one that is instantaneous.

Yes - the main isolator in the house fuse board and not the main 50A switch!

I am glad you intervened - so you are saying that an incoming live from the Linky cannot have a tee on it before it joins the isolator in the fuse box? ie there must be an uninterrupted run between Linky and fue board?

In which case, if so, implies that the desire to create a separate fuse box at the other end of a house for a granny flat, requires that the main feed comes from the [what I call] the cold side of the isolator?

I have not done this, but I can easily rectify it. My thinking of taking the flat feed from the live side of the isolator is that if work had to be done on the main fuseboard, the flat would not be cut off - not that it matters in this case as there is nowt critical in the flat fuse box and it is off most of the year anyway…

Thanks for pointing it out!

Spending an hour with a coffee looking at the vast array of prices for a LeGrand digital timer - mainstream cheapest is 70€ and expensive 122€ with a host in between! Then on Leboncoin, one for 50€ :grinning: :grinning:


Badger, may I impose on you a little more please?

Since posting, I have been looking at tariffs in general and my use of electricity and think that I have been missing out on things the past years by not using HC to its full…

For heating, we have a Daikin air pump and underfloor (heating under limestone tiles that are 20mm thick). The house is well insulated and double glazed. All this backed up with a wood fire.

There are two hot water tanks and the pool pump, all of which could go onto HC with the UFH and Daikin. Maybe even the dishwasher (we are a bit lax in it is often used during the day)

Is it acceptable to have multiple HC arrays (ie the 2A MCB, 20A MCB and day/night contactor combination) in one fuseboard? I guess if it is, that they should all be in a dedicated ID protected group, yes?

Is there a ‘soft start’ device one can add to this new group that will soften the sudden demand of these items?

Your comments appreciated!

Yes, but you probably don’t need it if individual devices can be programmed to do their own thing. There’s no reason that they should all share the same ID.

I’m not aware of anything but, again, individual programming will create the same effect as well spreading the load across the HC period, which may avoid a black out.

Thanks for this Badger!

Since writing, I have obtained four Legrand timer switches with batteries and a Schneider RT2012! Allegedly surplus to a job that the boss gave to her for ‘some pocket money’. I am a trusting sort of chap and went along with the bargain… :roll_eyes:

I am giving up on the UFH. 80A for the whole house for not a huge amount of heating.

I have been manually experimenting with the air heat pump coming on between midnight and 5am ahead of installing the timers that is surprisingly good - it keeps things inside warm, decreasing to 15 degress in the evening. But we have not had a really cold spell yet so it might change. Washing machines are on a strict do not touch until after 9 regime. I am annoyed that all this was not thought of years ago :laughing:

Two days with the RT2012 meter temporarily installed, is showing all this doing quite well with the HC use noticeably shooting up at the expense of the HP, so think I will definitely go to Tempo…

BTW, how accurate are meters such as then RT 2012 that use ‘tores’ (what are they called in english?) - it is the same technology as multi-meters with a clamp attachment, yes?

Thanks, Adam

Very accurate - yes, same idea as clamps meters.

English name would be “current sensor” or “current clamp sensor”.

By “9” you mean 21.00? I’m not aware of any HC starting that early - 22.00 seems to be the earliest.

Thanks - I was not sure! Before I hook up in earnest, I shall of course check out the correct times…

I am though really taken with my RT2012 and having great fun with it sniffing the various circuits being used! Another question please - if I clamp several circuits together, eg the lights and power for one room, will I I get a reading of the combined amperage of the two circuits?

Actually, one more if I may - how are Watts calculated by EDF - is it 230xA or 220xA or even 240xA - indeed what is the nominal voltage supplied to domestic users? Mine hovers around 226 and 229.


I don’t know the answer to that, You could easily find out by measuring each one then doing them together.

European harmonised mains voltage is 230V. Supplies in France must deliver 230V +/- 10% at the PDL - it’s in their contract.

Ah! Good logic :wink: I will do this and post back…

It depends. Current clamps are generally directional. If they are, they should have an arrow on them showing which way to mount them, from source to sink. If all your clamped cables go in the same direction, then they should add up. If not, then they won’t.