downlight advice please

[leighprice23]

hi all
couple of questions for you
im putting some downlights in the frontroom and bedroom shortly as im building a new ceiling on the existing and we will be putting downlights in
6 in the livingroom and 4 in the bedroom ,but thats here nor there
i want to use some lutron dimmers so im making sure i get the right lights
the gu10 seem popular and there are fire rated versions as is here Fire Rated Mains Downlights GU10 Halogen
will these do the job?
as its going in the ceiling which will be packed out with insulation of some sort will these type be ok ? ,or which will?
and will they work with the lutron dimmers?
as you can see im pretty confused so any advice is more than welcome

many thanks
leigh

[dalethecaptain]

Which type/family of Lutron dimmer do you wish to use? I'm going to make an assumption it's a Rania type, in which case it should be OK.

These lamp fittings are OK, but can be had from Screwfix in a ten pack for maybe a bit less. However, if you are doing a new installation you should think about adding transformers and using low voltage light fittings, they will use less energy and the lamps last longer. Also, I'm pretty sure that Part P regulations come into play when installing new lighting, so I think you need to get your local building control officer or qualified electrician involved.

[leighprice23]

hi thanks for the reply
your right regarding the lutron ie the rania
happy to go with the low voltage/transformer option
so i take it they would be compatible with the rania? as that was my only worry
and i know plenty of sparkies so thats no problem

cheers
leigh

[dalethecaptain]

I use a Rania dimmer unit with a Halolite HS60 60va prewired transformer, they are about £9 each but they do the job. I used one 60va transformer for each lamp, as when I first put them in my wife was concerned certain areas were not bright enough, and I did not want to be upgrading transformers buried in the ceiling.

If you want something a bit more robust, Lutron make their own transformers which are compatible with all their products, these are around £12 + vat each.

Its a little more outlay to begin with, but they pay for themselves pretty quickly in reduced electricity bills.

[leighprice23]

thanks again i shall have a look online
one more thing though
i take it the low voltage ones stay pretty cool?
ie they will be ok in a ceiling padded out with insulation etc or do they need breathing space ?
cheers

leigh

[dalethecaptain]

All the units on sale in the EU are supposedly rated to be used in ceiling voids and on top of insulation, some can even be used on sensitive surfaces, so you can place on or near to surfaces with risk of overheating or fire. The LV transformers in my house are just placed on top of the insulation material.

The lamps get hot (as do mains voltage units) so you need to place a hood around the fitting to comply with fire ratings or use a fire rated light unit.

[MitsiTurbo]

I used these loftcaps on all my downlighters on the top floor (i.e. the ones that are mounted into the ceiling below the loft). They allow you to re-lay the insulation over the top of the light without risk of overheating. You shouldnt lay insulation over the top of lights even if fire rated as they have holes in the back to allow heat out. I used the loftcaps with fire rated lights aswell but this isnt essential.

Fire Vapour & Thermal Seal Loft Cap

Hope this helps

[habrown]

I would recommend Low Voltage everytime over GU10's. The quality of light is much greater than GU10's, therefore much more energy effiecient. a lot of the GU10 energy is consumed into heat. you can really notice the heat off of a GU10, and heat is just a loss of energy!

The best transformer on the market are Mode Liighting ET-C's. They are silent and can be controlled by trailing or leading edge, and really are fit and forget. they are more expensive at £13.00 each, but were the recommended transformer from Lutron, before they decided to make their own!

[MarkP80]

I would recommend Low Voltage everytime over GU10's. The quality of light is much greater than GU10's, therefore much more energy effiecient. a lot of the GU10 energy is consumed into heat. you can really notice the heat off of a GU10, and heat is just a loss of energy!

- you still get a lot of heat passing back from a low voltage halogen though, that's for sure.

I used these loftcaps on all my downlighters on the top floor (i.e. the ones that are mounted into the ceiling below the loft).
Fire Vapour & Thermal Seal Loft Cap

- Do you use these with LV downlights? If so, where did you put the transformer? In the past, I have fitted individual transformers to each downlight, slimline units through the same hole, so they can be slid back out if they need to be changed. What did you do here? Can the transformer go under tha cap too? - Would it not get too hot? - Or have you put the trasnfromer outside the cap, and assumed access from above (in the loftspace). I ask because I've been pondering this issue for some time, as I will be doing some work in upstairs rooms before too long, and want to get the insulation right, without the fire risk!

Regards,
MarkP

[silver12]

The best thing to use is a fire rated downlighter - do not purchase from Screwfix or the like, go to a proper electrical wholesaler. Companies such as City Electrical Factors and Edmunson's are nationwide.

I prefer the Click brand, but many do get on with the JCC ones.

Ensure that you buy decent quality lamps and do not use the rubbish ones they supply with them - GE are a good example, as are Sylvania.

There is no energy saving in using ELV (12V) lamps over mains voltage ones, anyone who assumes as such is sadly misinformed. There is something to be said for a slightly longer life expectancy when ELV lamps and fittings are used, but for me the difference isn't worth the extra cost of decent transformers.

The heat output from any standard downlight is extreme, hence the need for a fire rated fitting (there are also acoustic considerations, as per part E of the building regs). You need to leave a 50mm gap around all of the fitting, in every direction.

You may wish to consider buying compact fluorescent lamps (these do come in a GU10 form factor), as these will save you a fair old whack on the electric bill. They run at about 8W as opposed to 50W and have a similar light output.

As someone has mentioned, there are the Part P regs to consider, but these are only relevant if you are installing a complete new circuit. You still need to test anything you install (and I'm assuming a DIYer doesn't own the kit), so have a word with a friend electrician and he'll quickly do it and you can buy him a drink.

[MarkP80]

Been doing a bit more research on this. It seems your normal dichroic LV halogen bulbs aren't suitable for fire resistant fittings. These allow a lot of heat through the bulb back into the fitting. For fire resistant fittings you should use bulbs with an aluminium reflector according to this

I was wondering earlier about using the loftcap, and which side of it the transformer would go. Well, perhaps an alternative solution is to use a fire resistant fitting like this, then use something like this cover - this solves a couple of issues. It allows the air space to be maintained around the fitting while letting you put your loft insulation over the top, and also provides the space for you to poke that slimline transformer and JB through the hole when you install them. OK, not necessarily the cheapest solution, but certainly makes the installation simple and straightforward, does it not?

Cheers,
MarkP

[silver12]

For clarification matters, LV is anything below 1000V AC and 1500V DC, so the lamps you're referring to are ELV.

Almost all lamps supplied by anywhere decent (not B&Q et al) have reflective inners, however the heat output through the rear is almost identical, so fire rated fittings are still required.

There is the option to fit fire hoods, or a fire blanket, but standard downlight fittings do not comply with Part E of the building regulations, therefore a fire rated fitting solves this issue.

When installing any electrical items the install must comply with Parts B, E, L, M and P of the building regulations (by law) and it is also strongly advised to comply with the BS7671 wiring regulations, although these are not mandatory.

[neilball]

Originally Posted by silver12

For clarification matters, LV is anything below 1000V AC and 1500V DC, so the lamps you're referring to are ELV.

Almost all lamps supplied by anywhere decent (not B&Q et al) have reflective inners, however the heat output through the rear is almost identical, so fire rated fittings are still required.

There is the option to fit fire hoods, or a fire blanket, but standard downlight fittings do not comply with Part E of the building regulations, therefore a fire rated fitting solves this issue.

When installing any electrical items the install must comply with Parts B, E, L, M and P of the building regulations (by law) and it is also strongly advised to comply with the BS7671 wiring regulations, although these are not mandatory.

Your comment about all lamps passing the same amount of heat back through their reflector and into the fitting/ceiling void is not correct. As MarkP80 has stated there are MR16 lamps with aluminium coatings which reflect most of the heat produced forward into the room and many (if not all) fire rated lv fittings require the use of this type of lamp. This is very different to standard MR16 lamps (sometimes called cool beam) which allow most of their heat (and a reasonable amount of light) to pass through the reflector and therefore not into the room. If the OP is in any doubt then they could look at the lighting packs sold by the likes of Aurora which have the fitting, transformer and correct lamp supplied together, this will ensure they are all compatible.

[silver12]

I said that anywhere decent selling lamps (either MR16 or GU10) provide reflective inners, these are almost identical to any supplied through TLC which claim any greater degree of reflectiveness or heat protection. If you measure the heat output through the rear of a lamp fitted with a reflective inner using a thermal imager you'll discover the difference is nowhere near enough to consider not using fire rated fittings (not that you suggested not to).

Aurora are a fairly decent brand of light fittings, and their fire rated fittings I personally think are one of the best.

If money is no object for the OP then LED fittings would be the best option, however cost is considerably higher.

[MarkP80]

For clarification matters, LV is anything below 1000V AC and 1500V DC, so the lamps you're referring to are ELV.

- You're correct of course, but for most DIY'ers 230v is the maximum voltage we deal with.

When installing any electrical items the install must comply with Parts B, E, L, M and P of the building regulations (by law) and it is also strongly advised to comply with the BS7671 wiring regulations, although these are not mandatory.

- but only if those regs apply. Part P doesn't necessarily, for example.

If you measure the heat output through the rear of a lamp fitted with a reflective inner using a thermal imager you'll discover the difference is nowhere near enough to consider not using fire rated fittings (not that you suggested not to).

- Just to clarify, I certainly wasn't suggesting the use of non-fire resistant fittings, (as silver12 acknowledged), just noting that a fully enclosed fire resistant fitting is enclosed at the rear and so heat build up is retained, whereas a conventional fitting doesn't suffer from this. Clearly, it doesn't form a fire barrier either though....

As for the quality of the bulbs, I don't profess to be an expert, but it was my understanding that conventional dichroic halogen bulbs only reflect visible light frequencies, but allow non-visisible radiant heat to pass through, whereas bulbs with aluminium reflectors do not. Different types as opposed to different qualities?

Edit - quickly Googled - Glossary - gives a definition for aluminium reflector and dichroic.

MarkP