rewiring 1970's electricals

[RickTizzy]

Hi all,

Just to be clear, I'm not looking for advice on upgrading but rather just clarification of our existing setup.

We need to upgrade the electrical panels on our recently purchased property in France, but before we get somebody in who's native tongue is not our own I was hoping to gain a better understanding of what it is we currently have at the moment. Thanks in advance to all the helpers here willing to spend their time on us.

According to the reports we had made when we purchased the house, we need to add residual current circuit breakers to replace the old earth breakers.

I'm obviously no professional but I do have quite a few years experience with general electrics and renovating and have done quite some research on my own over the years so I do believe I have a general though perhaps still superficial understanding of the concepts. I am aware of the difference between the two and the purpose behind the upgrade though. But perhaps someone here can help properly clarify our current setup (without country code specifics because we're in France) before we get the professionals in.

I've included some pictures of the current panels and will describe them as I currently think to understand them. Please correct me if I'm wrong or query me if I need to complete anything. As follows:

• We have a main incoming switch panel (A) connected to a meter (B) connected to the main breaker panel box safeguarding the house (C), which connects to an old fuse panel for our electrical heating [Chauffage] units (D).
• The breaker box panel (C) splits off to the old fuse panel (D) in a seemingly 3 phase star configuration judging by the 40A breakers.
• The C panel also apparently supplies a 3 phase delta config (again judging by the breakers) 16A circuit for a pump [Pompier] of some sort (E).
• C has a general earth circuit breaker but that excludes the 32A breaker for the oven [Cuisiniere] for some reason.
• C also covers the hot water boiler [Chaufeau] which runs on a separate 25A high and 2A low tarif circuit.
• C includes single pole breakers for 3 lighting circuits [Lampe] and 6 wall sockets [Prise]

D has apparently not been upgraded since the 70's (except for the relatively minor addition of a air circulator unit) and handles the circuits for the 7 electrical heaters.

This panel D is rather unclear to me because what I'm seeing is split fuses (which I think I understand) but with red (Live) and blue (Neutral) wires apparently not needed for all circuits. How do these fuses relate to the incoming 3 phases + neutral I also wonder, and how then and are the 3 (red line) fuses in the centre of the box the fuses for subcircuits? I'd really like to understand how they are using the 3 phase star config to power the heaters as each one is 220V and powered through it's own ancient thermostat using just one wire from the 3phase fuse box but there are 7 electrical heaters throught the house. If I'm not mistaken, each phase in the star config only carries about 90V so I'm rather confused as to what's going on.

Anyways, I hope I'm not blowing anybody's mind with these old designs. Merry christmas and best wishes to all!

 

[timhoward]

Welcome. There are some people who linger here that specialise in French electrics. @Mike Johnson may be able to help.

In general earth leakage circuit breakers are significantly inferior to RCD technology and cannot be guaranteed to actually work. I don’t know how prevalent they are in France but in the UK we replace them if we find them.

The only other general comment is that being clear in your mind what are single phase circuits (using a neutral) and what are 3 phase circuits (using the potential difference between phases and needing 3 phase wires) is a pre-requisite to making headway understanding it.

Even though 3 phase supplies are common in France my understanding was that it is usually mainly single phase appliances, making use of any phase to neutral.

I’d be surprised if the electric heaters are 3 phase but happy to be proved wrong!

Hopefully a French expert will appear soon.
All the best with your voyage of discovery!

 

[RickTizzy]

Thanks Tim. I realise it's a lot to analyse but hopefully someone can make head or tails from what I've described in combination with the foto's. It's obvious that some of the breaker panel wiring has been redone and that person apparently wasn't willing or allowed to touch the 1970's wooden fuse box, so I'd really like to understand what it is we're dealing with before getting somebody in.
All the heaters show 220v connected, so definitely not 3 phase at the end points, but the breaker supplying the wooden fuse box from the main panel says 400V in a star config (red in the picture here) if I'm not mistaken....

How could they be doing that is what I wonder.

 

[pc1966]

It is common to use a 3P breaker for a 3P+N circuit, or to feed a small 3P sub-board that may have a mix of SP and 3P loads, as in many cases you do not need the neutral isolated, and that might be more desirable to avoid a very brief time when N is open but some P are closed and your single phase devices can see above 230V (France is technically 230V now, just as UK, but in practice you will see closer to 220V in France and 240V in UK due to historical practice).

It is very likely the pump would be 3-phase and delta connected load (i.e no N).

Other things like heating might be on a 3P contactor even if individual heaters are SP. The blue thing looks like a radio switch for cheap electricity, related perhaps to heating?

The other cases domestically of 3P (in UK) are big water heaters (much above 10kW), and in recent times fast EV chargers. In France, due to the generally smaller supply settings (they your tariff sets), you may well see smaller water heaters being 3P to balance current over the phases.

However, you really are looking at replacing the whole lot post-meter. Those Merlin-Gerin boards are very good, but past useful their life and upgrading to RCBO, etc, would be as expensive as complete replacement, if not more, and you have the ancient stuff to deal with. Also now I expect you should be fitting a SPD and you might need to consider the location and nature of supply cable to decide if they bigger (and much more expensive) type 1+2 sort are merited.

I would suggest you take stock of what is already installed, and think carefully about what need changing such as more sockets in rooms for today's electronics, stuff like EV charger looking forward, and any change to room usage that might need special care (e.g. bathrooms). Also if you have sheds or other out building, do you need power there? If so, how much?

Build up a plan for getting a couple of quotes from local sparkys. Also try and get to know locals to find out who they would recommend (assuming not in the middle on nowhere and only one choice!).

 

[Mike Johnson]

The second photo in your first post shows the EDF incoming RCD, the widow beside the test button will show your power allowed per phase, if you go above this the RCD will trip and the whole house supply will go off, this is designed to protect the EDF cable and not you or anyone in the household, and ensure you can't get more power than you pay for on your standing charge, my main concern is where is the Earth, normally for a rural property this will be a TT system, i.e. an earth rod driven into the ground and run to the main board, before you do anything ensure this is present. Once you have verified that I will try to help further.

Get a copy of this book: L'installation électrique - David Fedullo , Thierry Gallauziaux -... - Librairie Eyrolles - https://www.eyrolles.com/Loisirs/Livre/l-installation-electrique-9782416000058/

 

[RickTizzy]

Thanks guys, very much appreciated you sharing your expertise and spending time on us.

I'll have a look to see if I can locate the earth connection as we do have earth in various locations in the house such as the heaters and oven, just not the regular wall sockets.

At the moment I have removed a few of the heaters and as they're all 230V I've used the supply for regular earthed sockets. Hopefully we dont blow a fuse before we're finished replacing everything because finding those old replacement fuses will not be an option I suspect. Eventually all house heaters will be removed including the whole subsytem. I'll be installing hydronic floor heating, heated partially by wood stove with an electric boiler as a buffer. It will be a while before that's concluded though.

We will indeed definitely have everything replaced as well as extended for outside use in an annex I'm building for woordworking and mechanical equipment which will need 3phase as well. Making a plan layout is definitely crucial and a good idea.

We are almost quite literally in the middle of nowhere in Reigny, Cher. But so far we've had some luck finding tradesmen willing to commute the 25km's from the nearest larger cities. Thankfully I have quite some years experience with most things renovation and can do most things myself, but whole house electricals are not worth the risk or even DIY insurable.

About the EDF RCD you mention Mike, it's maxed out at 30A currently (no pun intended). We have increased our Linky supply from 9KW to 12KW but now you've clarified things I suspect 12KW is pointless if this thing is still connected and we are indeed still getting occasional brownouts. Will they just remove it entirely with the Linky (which is actually located out on the street) as the failsafe, or replace it with something in the house that can handle more power?

 

[pc1966]

As @Mike Johnson has pointed put you are almost certainly on a TT earth so you must:

• Find your earth rod, and;
• Check it is in serviceable condition (cable good, not sign of excess corrosion), and;
• Verify the rod Ra is below (probably) 100 ohms to ensure safe tripping of the supply RCD in the worst case

You need to ask the supply company about the max the can offer, it is determined in France often by the tariff you pay but in rural areas you might find it is limited by the supply cable voltage drop so it might be 30A is the max they will provide.

Also if rural you might find lightning surges are a real risk and probably having a type 1+2 SPD, at significant cost, along with a short direct earth cable to the rod is needed for it to last, and to protect your electronic equipment. Which these days is practically everything (LED lights, white goods with computer controls, TV/internet/PC, etc)

 

[Mike Johnson]

As above your priority is verifying that you have an earth rod, everything else takes a back position it's imperative that your verify this as it could kill you, none of the safe guards will work without it, you even state that the earth is not present in some critical areas, do not do anything else concentrate on the EARTH into your property.

Can not emphasise this enough.

 

[Mike Johnson]

just not the regular wall sockets.
Dangerous situation should be rectified as a matter of urgency.

About the EDF RCD you mention Mike, it's maxed out at 30A currently (no pun intended). We have increased our Linky supply from 9KW to 12KW but now you've clarified things I suspect 12KW is pointless if this thing is still connected and we are indeed still getting occasional brownouts. Will they just remove it entirely with the Linky (which is actually located out on the street) as the failsafe, or replace it with something in the house that can handle more power?

The EDF RCD is adjustable by EDF and yours is set at 30A per phase (maximum) so 90A available as a balanced load, I ran my woodworking shop on 20A per phase quite possible if only working by yourself on one machine at a time, splitting the phases between machines and extracts. The Linky is only a metering system and nothing to do with the maximum power supply, also they have proved to be problematic in some installations.

I cured most Brownout situations by putting overnight timers on the water heater, the occasional switch on during the day was causing an overload on one phase, so the whole thing tripped out.

 

[Mike Johnson]

As @pc1966 says some kind of lightning protection is a good idea in a rural setting, our own place was in Dordogne the lighting capitol of France, we where constantly hit and had to replace the surge protector at regular intervals, this works out very expensive on a three phase installations, eventually we just switched everything off when a thunderstorm was near before we where hit, I don't know if resettable surge protectors are now available as its over ten years since we sold up and moved back to the UK.

 

[Mike Johnson]

See here: https://www.schema-electrique.net/mise-a-la-terre-installation-electrique-norme-NF-C-15-100.html

Earth connection is mandatory under French Regulations, open the above in Google, go to settings and use translate button if your French is anything like mine was.

 

[RickTizzy]

I very much doubt my french is better than yours was, thankfully I did pay some attention in school even tho it was a hundred years ago. Reading it is happily a lot easier than listening to it tho

The electrical report we got from when we bought the house did mention a number issues of course including the ancient box and wallsockets, as well as the earthing and the RCD's, but it didnt specify the connection rods or some such. I'll verify it before doing anything else, thanks for your concern. It'll have to wait a few weeks but I'll get back here asap.

In the meatime I wish everyone all the best for the near and far future and thanks again for all the time and effort!

 

[pc1966]

It'll have to wait a few weeks but I'll get back here asap.

How did it go?