sid Posted February 12, 2013 Share Posted February 12, 2013 I've consulted my "Installation Electrique" and Googled a bit but can't find a definite answer; is it permissable (normes and any other regulations) to drill a hole (16mm) through several ceiling joists in order to pass a gaine through for a lighting circuit?Background: Our kitchen ceiling is very dark, the joists are exposed and you can see the floorboards of the room above. I would like to install plasterboard between the joists, leaving only about 8cms of the joist visible, and at the same time install LED downlighters (mentioned on another thread). The joists run across the width of the room, so in order to get an electrical supply to the other end of the room I am limited in where I can go as the walls are pierre apparentes. I would need to pass through 5 of the 9 joists. The joists are 19x7.5 cms (which doesn't seem to be a standard size?).Apparently the gaine mustn't lie on top of the plasterboard, but must be fixed to the solives. That's the only bit of useful information I managed to find!Secondary question on insulation: I envisaged a layer of fibreglass insulation (12cm), do I need a vapour barrier backing to the insulation? Link to comment Share on other sites More sharing options...
NickP Posted February 12, 2013 Share Posted February 12, 2013 Sid drill the holes pass the gaine through; put the plaster board in place, what gaine what holes? [Www] When I fitted down lighters in a ceiling I made up small boxes that sat above the plasterboard so the lamps had an air space around them. I'm sure some self appointed "norms" lawyer will come along and say different, where's 3P when you need one? [:D] Link to comment Share on other sites More sharing options...
sid Posted February 12, 2013 Author Share Posted February 12, 2013 Nick, I've made it a rule to do things properly, and although I could just drill the joists and hide every trace I'd like to know what the pro would do (assuming that he wouldn't just hide it !). For example, I've replaced a lot of wiring during various stages of renovation and found (and replaced) some pretty bodged DIY jobs, so I'd prefer carry on like that. DIY doesn't need to look amateurish.It would only be a 16mm hole, so I'm probably OK, but I seem to recollect reading that the hole should be near the top of the joist because this is the least stressed part?? Link to comment Share on other sites More sharing options...
Quillan Posted February 12, 2013 Share Posted February 12, 2013 For downlights I did much the same as Nick. I ran gange round and where I wanted the lights I put a box and the downlight has a short length of three core 'flex' from the fitting to box, just enough that the light mount would hang about 6" below the ceiling just in case I needed to change them at some stage.If your worried about drilling the holes then you could put wooden 'plates' either side to give back any strengh you have have lost through drilling the hole. Link to comment Share on other sites More sharing options...
sid Posted February 12, 2013 Author Share Posted February 12, 2013 Q, I'm OK about the actual wiring, although any connection boxes are supposed to be accessible. I suppose you could argue that the box is accessible through the ceiling hole of the light fitting although you'd need small hands.I'm more worried about the drilling. Maybe when I've fitted the placo it'll be out of sight, out of mind! If I used cable instead of gaine the hole would be smaller but I don't know if cable would be correct for this application. I prefer the gaine system. Link to comment Share on other sites More sharing options...
Chancer Posted February 12, 2013 Share Posted February 12, 2013 Dont worry about the drilling, what you are going to do is inconsequential, the fibres above the neutral axis are in compression and thats where you want to drill anyway, as high as possible above the insulation.Pare vapeur between floors serves no purpose, personally outside of climates like Canada I dont believe it has a purpose anywhere in a building other than theoretical and to make the French pay more for an alleged superior conforming product, its actually quite hard to find insulation here in France without a pare vapeur, it exists but never in the size you want and often costs more [:-))] In your case it will make the handling and temporary fixing of the insulation easier with a pare vapeur. Link to comment Share on other sites More sharing options...
Quillan Posted February 12, 2013 Share Posted February 12, 2013 [quote user="sid"]Q, I'm OK about the actual wiring, although any connection boxes are supposed to be accessible. I suppose you could argue that the box is accessible through the ceiling hole of the light fitting although you'd need small hands.I'm more worried about the drilling. Maybe when I've fitted the placo it'll be out of sight, out of mind! If I used cable instead of gaine the hole would be smaller but I don't know if cable would be correct for this application. I prefer the gaine system. [/quote]I found the small round boxes in BricoDepot just happened to be the same size as the hole for the lights, more by luck I have to admit. I put my cable in gange but my electrician said there was no need and just to run three (solid) core cable. They are run in a star formation from a box above the wall unit mounted in to the wall. I am not an electrician and don't know the regulations. He is a qualified French electrician, or so it says on his documents, he tells me where to lay the cables. I connect the sockets, switches and lights he then checks and makes them live. The other difference to you is that I dropped my ceiling by about 4" to get the downlights in because the original ceiling is concrete. Link to comment Share on other sites More sharing options...
Théière Posted February 12, 2013 Share Posted February 12, 2013 In a kitchen I would rather use rock wool for fire reasons, glass fibre melts at too lower temperature so affording no delay in the event of a fire.Q, I am not sure that the french electrician is correct as there needs to be two insulations between conductors and just using solid core would not comply?Anyone else? Link to comment Share on other sites More sharing options...
sid Posted February 12, 2013 Author Share Posted February 12, 2013 That's interesting about the rockwool v fibreglass! It makes me wonder about the placo that you see with polystyrene on the back, surely that's not a great fire-retardant either?For the wiring, use of 3-core (or more) cable is OK where it's accessible I believe, and you often see it in outbuildings (sometimes running in supporting lengths of IRL tubing), but otherwise wiring should go in gaine. I'm not sure that I understood this bit properly, but two insulators between conductors is satisifed though, isn't it, if each core is insulated? Not that I like the idea.So, if I understand correctly Chancer, I can drill through the joist but it needs to be at the top rather than low down. That'll do, thanks. Link to comment Share on other sites More sharing options...
Théière Posted February 12, 2013 Share Posted February 12, 2013 [quote user="sid"]I'm not sure that I understood this bit properly, but two insulators between conductors is satisifed though, isn't it, if each core is insulated? [/quote]I am not sure I wrote it properly [;-)] I should have said between customer and conductor there should be two layers of insulation, hence lengths of flex would comply but singles without the gaine wouldn't.The poly insulation shouldn't burn and should be low smoke and self extinguishing once the flame is removed but that's another story. Rock wool is still the best for sound insulation, thermal insulation and fire retarding, in short a tough act to follow in the right place. Link to comment Share on other sites More sharing options...
BIG MAC Posted February 12, 2013 Share Posted February 12, 2013 Speaking from what we are doing ..holes should be about 3/4 the way up the joist and aligned as best you can, going higher opens the risk of a nail strike from above. I would run in pre wired gaine and JBs but I believe (please check) that 'flex' is permitted as the PVC sheathing is an insulator as is the sleeve for the individual conductors / wires.Its simple enought to 'strap' the sides of joists then insert placo to hide the cable runs and create a void for downlighter pots. Link to comment Share on other sites More sharing options...
sid Posted February 12, 2013 Author Share Posted February 12, 2013 Thanks, I think I'm sorted now, just the downlighters to source... aren't they dear here! Heard that before! [:D] Link to comment Share on other sites More sharing options...
BIG MAC Posted February 14, 2013 Share Posted February 14, 2013 Keep an eye on Lidls who get them in from time to time ...I was paying €5 for a pack of 6 when I got them a couple of years ago. Link to comment Share on other sites More sharing options...
Théière Posted February 15, 2013 Share Posted February 15, 2013 To my knowledge Lidl's don't yet supply fire rated down lighters and certainly not at that price. The cost and fiddly nature of trying to fit the fire hoods to these cheap fittings makes it not worth it. Link to comment Share on other sites More sharing options...
BIG MAC Posted February 17, 2013 Share Posted February 17, 2013 a) I didn't say mine were fire rated.b)The price was why I bought about 30 sets.Fire hoods are easier to fix to the boards before putting them up. Presumably if one was using insulation one would need the hoods in any case. Link to comment Share on other sites More sharing options...
Araucaria Posted February 18, 2013 Share Posted February 18, 2013 The electrician who put it on our downlighters is a qualified man, French, and does contract work for a number of the businesses round here. I think he knows what he is doing.Instead of using fancy boxes above the downlighters to keep them away from the insulation, he simply used large tin cans (somewhere between the ordinary size and catering size of haricots verts) with both ends taken off. They sit on the plasterboard above the light and protect the light and fitting from touching the insulation, and provide a bit of ventilation too - downlighters can get hot. However to do this ideally you need access above the plasterboard, which the OP might find more difficult. Link to comment Share on other sites More sharing options...
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