What size earth rod do i need?

So, at last I have a working electrical system in the property.

New circuits, new dis board.

I now need to tackle the problem of installing an earth rod to complete the work

How do I calculate the size of the rod? L x D

What material should it be?

What size earth cable should I use?

Is there an english translation of the NF document covering this?



None of my heavy-duty earth wiring is in a gaine, but the regulations could have changed in the meantime. Mine runs inside a plasterboard riser (where the main panel is located) to the barrette de coupure, which is mounted on the outside of the plasterboard. It then runs inside the plasterboard directly to the vide sanitaire, which is where the earth rod is located.

None of the wiring, whether live, neutral or earth, should be readily accessible by anybody, so I'd put it in a tube if it could otherwise be seen; e.g. running down a wall, inside or outside.

Do I need to use gaine?


A little error slipped into my message. (It was over 20 years ago that I was involved in doing this.) Where I mentioned the official Conseil inspector, I meant, of course the Consuel inspector. This is the geezer who will give you the chit necessary, by law, to connect your new installation to the public supply. We had to have it for a new house, or EDF wouldn't connect us (before ERDF existed). Apparently, you're supposed to have it for a major electrical renovation as well.

FYI, if you haven't heard of it, Consuel stands for Comité National pour la Sécurité des Usagers de l'Électricité. We had to wait nearly 3 months for them to turn up, although at the time they had a commitment to turn up within, I think, 3 weeks of applying. How was this done? You were only allowed to apply on their official form & they simply delayed sending that out!

Hoping I'm not teaching granny to suck eggs, but others reading this might find it helpful if you're already on top of it. More info about the Consuel is on here, which happens to be a French equivalent of Meerkat comparison sites.

Perfect! Thanks for that

Ahh I wondered what that thing was outside our Kitchen, it's been sprayed in cement and was something on the list to get around to looking at sometime.

I see that barrette de coupure are 10€ - 15€ in Brico Depot, so well worth fitting.

Don't forget to add the little device known as a barrette de coupure between the main distribution box and the earth rod. This allows for testing the system with the earth disconnected and is something that any electrical inspector (official Conseil or diagnostique, when selling the property) will be looking for. Between that and the distribution box, the section can be 10 sq mm if the main supply is 10 sq mm or less. If the main supply is more than 10, it must be at least 16 sq mm. Between the barrette de coupure and the earth rod, the section must be at least 16 sq mm if the cable is copper & insulated (green/yellow, of course), 25 sq mm if uninsulated copper and 50 sq mm in the case of uninsulated galvanized steel.

This site http://www.schema-electrique.net/mise-a-la-terre-installation-electrique-norme-NF-C-15-100.html is pretty comprehensive & probably easier to understand than the norme itself. (Put the link address into translate.google.com if your French isn't up to it.)

I did most of mine myself with help from Alastair Wiseman I would recommend at least 1 metre rod and copper if you can find one then get it deep into the soil somewhere it will not get to dry better resistance if damp. Bond all your water pipes and gas if you have

Technically (not that I'm at all qualified) I understand that you are supposed to use an Earth rod that gives you a minimum value of resistance (?) when measured. What that value is, and what you use to measure it, is probably Country dependant with France no doubt being different to everyone else.

What the Earth rod goes into and its length, is also proportional to the measured value with (I'm told) gravel soil being the worse (needing a much longer rod). Currently I am also fitting an extra Earth rod to my Barn and am simply using a standard 1.2M UK rod and 16mm csa cable.