sunken ceiling lights and fibreglass problem/question

[happyhero]

Hi, I am a retired building services man, which means I am a qualified electrician, and no I don't have part P because I am retired. Despite being a qualified electrician I have never done a job like this at work as the work was more industrial than this sort of domestic type here, hence the question.

I am fitting some recessed mains voltage fire rated fittings in my extension. The void in the ceiling is approximately 6" to 8" deep with a plasterboarded ceiling and fibreglass wool insulation of about 4" thick. The hole I am cutting for the fittings is 62mm, ie not big enough to get my hand in.

I don't know what to do about the fibreglass, the whole is very small to successfully cut a hole in the fibreglass to allow the lamp to slot into or even have a gap round it and I am not sure if it is ok to just push the lamp in and allow the wool to rest on top of the fitting. These fitting are fire rated and so don't need a hood and I know that mains halogen get very hot but not sure how hot this will make the back of the fitting and if it will be ok touching. They are about 5" deep, so my guess is they wont be very hot at the back, and I don't think the wool would easily catch fire but I don't want to test the theory.

Can anyone advise me, as to what is supposed to be done in this situation and what would an electrician actually do, ie sometimes there is a method you should use and sometimes electricians do it a different way because it makes more sense. I am not after bodging it but I don't want to go to any unnecessary work.

Any advice appreciated.

 

[RF Lighting]

If we are presented with this problem then the norm is to try and push the fiberglass away from the fitting to try and achive at least a 6" clearance round the fittling. We use something like a cable fishing rod to move the fiberglass.

Your fittings are fire rated. This prevents fire from penetrating the fitting, it does not prevent the fitting from setting fire to something which it is mounted too close to.

You do not need fire rated fittings unless there is a seperate dwelling above where you have installed the fitings such as in a flat, but there is nothing to stop you using these fittings if you have already bought them.

Make sure you install aluminium reflector lamps which project heat downwards, away from the ceiling void (these must be used in fire downlights). Do not use lamps with dichroic reflectors which send heat up into the void.

IMO the best option would be to install mains DLs and fit CFL lamps instead of halogen lamps, which will have no problems regarding heat, and based on 6 downlighter lamps you would enjoy a SAVING of £156 before you have to buy replacement compact fluorescent lamps.

Lamp savings calculator

CFL lamps

 

[happyhero]

Thanks RF Lighting, a very helpful reply but got a couple of questions.

Noticed you use TLC by the way, same place I use most of the time.

CFL lamps are interesting but what sort of light do they give off? I find a Halogen whether mains or LV gives off a really nice light and I have noticed that many energy saving lamps don't give off that nice a light even compared to an ordinary GLS light bulb which also looks better than a energy saving bulb. Also I notice that some energy saving bulbs take a while to come up to full brightness. I do see the saving with these being quite an advantage though.

Can you tell that these CFL's are not Halogens, and do they take a while to get to full brightness?

Also I am interested in this cable fishing rod type thing you mention, can you explain more, so that I can see if it is something I can rig up or do to remove the fibreglass?

 

[RF Lighting]

The CFLs that TLC are selling are made by megaman, which is one of the better manufacturers of CFLs

If you have a branch of TLC near to you, why not call in and see if they have a lamp on display.

We dont have TLC oop north, but the two different local wholesalers I use have them on display. (lit up)

IMO the light is better than traditional halogen DL lamps as it is more evenly distrubuted as opposed to the traditional pools of light from standard halogen lamps.

Also modern CFLs (well the good quality ones anyway) have moved on a long way in recent times and now have electronic control gear to acive instant switch on, and almost instant full brightness. They also have got rid of the harshness of the old fluorescent type light. Some of the megaman range can be dimmed with a conventional switch too.

No I don't work for megaman!




Cable rods are fibreglass rods which are thin and rigid enough to fit through the DL hole and push the fibreglass out the way