Lighting wiring.

[oldgit72]

A simple question I hope. I am planning my lighting runs and propose to do the following - from each run, lay a spur from a junction box to each light via a switch. Is this allowed or is there a better/different way. I have a 2009 copy of L'installation Electrique but the diagrams on p257 do not seem to show what I am planning.

[Punch]

You could do it that way, but it would use more wire and that would mean passing through the switch each time, to get to each light and having twice as many wires, and an earth wire ( which is not required) at the switch.

Normally I would have a local boite de derivation ( junction box) and then take conduits to switches and lights seperately from this boite. With the advent of DCL boxes which are a requirement on all new electrical installations, you do not really want to have too many wires in your DCL box!

Installation design is an important factor in electrical wiring and every job is different in the planning of wiring runs. Neutrals are not needed at switches but is is strongly recommended to have a neutral available at switches to allow for future expansion and changes such as PIRs, dimmers etc.

Hope this helps!

 

www.punchardrenovation.com

 

[oldgit72]

Thanks for the reply. Looking again at l'installation electronique, there seems to be an option to take the lighting run via the interrupteurs themseves. My understanding of this is that you finish up with a lighting run connected via switches with each switch then having an independent light controlled from it. This seems reasonably simple and would avoid the need for junction boxes and inspection points for them which could get messy. Have I got this right?

[powerdesal]

Of course that is quite feasible but, as Punch pointed out, you have much more wiring involved. LNE in and out of the switch plus L + N (poss E as well) to the light. In effect you would be using the switch as a junction box anyway and contact size / back box size could be a major issue.

[Chancer]

[quote user="oldgit72"]Thanks for the reply. Looking again at l'installation electronique, there seems to be an option to take the lighting run via the interrupteurs themseves. My understanding of this is that you finish up with a lighting run connected via switches with each switch then having an independent light controlled from it. This seems reasonably simple and would avoid the need for junction boxes and inspection points for them which could get messy. Have I got this right?[/quote]

Yes that is what I did and it was accepted for consuel, you will have to join the neutrals in each switch back box with a small domino that can be tricky but it is doable and accepted by Consuel.

I have highlighted the bit above as you can run more light fittings in parallel by daisy chaining from each DCL fitting, the ones I used had push fit wire terminals that would accept two 1;5mm cores in each hole at a pinch but no more.

[Punch]

[quote user="oldgit72"]Thanks for the reply. Looking again at l'installation electronique, there seems to be an option to take the lighting run via the interrupteurs themseves. My understanding of this is that you finish up with a lighting run connected via switches with each switch then having an independent light controlled from it. This seems reasonably simple and would avoid the need for junction boxes and inspection points for them which could get messy. Have I got this right?[/quote]

If I have understood you correctly, I can't see the point in wiring this way as you would need two conduits arriving at each switch. Normal practice in the majority of cases, is to have just one. It seems excessively wasteful and time consuming!

 Normal practice "in the field" is to daisy chain socket outlets and have accesible junction boxes for lighting circuits, with just one conduit to each switch /light/appliance. As I said earlier there are exceptions depending on the design, but having been in the game here in France for many years now, that method is quite unusual. Most installations require a boitier de derivation somewhere to make wiring simpler.

You can daisy chain lighting through a DCL box, but you may struggle connecting up as space is very limited. You can use switch boxes as junction boxes ( deeper versions are available for this), and sometimes it is practicable to do so, but not in all cases.

www.punchardrenovation.com

 

[Chancer]

Mr Punch is quite right, what I did is not at all common and has resulted in a few raised eyebrows and questions being asked.

It was wastefull of cable and yes I have two gains entering each light switch backbox which was difficult (I was advised that the outer gaine must physically enter the backbox, dont know if it is true in practice but I didnt risk it) my reason for doing this is that I cannot access the ceiling space above to locate the junction boxes and personally I hate to see them mounted at the top of the wall spoiling the decor.

None of my French friends share my view, because that is where they are traditionally put they just accept it and would never dream of asking the tradesman to do it any differently to suit their wishes.

[oldgit72]

[quote user="Punch"]

[quote user="oldgit72"]Thanks for the reply. Looking again at l'installation electronique, there seems to be an option to take the lighting run via the interrupteurs themseves. My understanding of this is that you finish up with a lighting run connected via switches with each switch then having an independent light controlled from it. This seems reasonably simple and would avoid the need for junction boxes and inspection points for them which could get messy. Have I got this right?[/quote]

If I have understood you correctly, I can't see the point in wiring this way as you would need two conduits arriving at each switch. Normal practice in the majority of cases, is to have just one. It seems excessively wasteful and time consuming!

 Normal practice "in the field" is to daisy chain socket outlets and have accesible junction boxes for lighting circuits, with just one conduit to each switch /light/appliance. As I said earlier there are exceptions depending on the design, but having been in the game here in France for many years now, that method is quite unusual. Most installations require a boitier de derivation somewhere to make wiring simpler.

You can daisy chain lighting through a DCL box, but you may struggle connecting up as space is very limited. You can use switch boxes as junction boxes ( deeper versions are available for this), and sometimes it is practicable to do so, but not in all cases.

www.punchardrenovation.com

 

[/quote]

Thanks for the advice, much appreciated. Just 1 more question re j/b's. I have seen in brico catalogues some Boites de derivation with several holes for conduits. Presumably these are for several spurs leading off .As I do not want too many j/b's, do you know what is the largest size j/b it is possible to buy in terms of the numer of conduits leading from it?

thanks

[Punch]

Largish one's that I have used are around 20cm x 20cm but I try to avoid having a large one unless it can be discreetly placed, and they can get difficult to install due to the number of conduits, when installed in a placo wall.

There is another couple of alternatives; Use a "boitier de combles". These are loft mounted junction boxes, some are square, some are round but they are much more solid and can take more conduits. Or if you have a cupboard or suitable location, use a surface mounted box ( the type used for exterior connections) mounted tight to the ceiling.

 

 

 

[oldgit72]

Thanks again - I've now got a much better picture of what I need.