I have two pairs of identical MR16 and GU10 lamps, ie same lamp internals with different fittings and power electronics, and they are good lamps.

Rgds

Damon

I think the material difference is that GU10 LEDs run off 240V where as MR16 run off 12V - they're both typically physically the same sized unit with generally the same LEDs and optics inside, but with one major difference:

In the top of the GU10 unit is a tiny individual 240v to 12v transformer - and from other's experiences it's the transformers that fail in these units - packing such a heat-producing and vital electronics at minimal cost in a tiny enclosed space is not a good idea.

My understanding is that this is the only tangible difference - however what MAY be relevant is that you get a better choice of unit available in GU10 because they are designed for retro-fit installs - so manufacturers make more choice as they have a bigger potential market of everyone who has existign 240v halogen downlighters.

The MR16s seem to be more aimed at new-build and people already converted to 12V, so a currently smaller target audience and hence they make less choice to keep costs down.

Hopefully the balance will change over time.

Posted By: WillInAberdeenI' m regretting downlighters, they let loads of drafts through the holes in the ceiling. Next time would choose dangling light fittings.

What I have decided on is to use track lighting rather than recessed fittings, hopefully addresses a number of issues. Only one electrical connection so reduced fitting costs, no cut outs in the ceiling and better cooling of the light fitting hopefully.

Ikea do an affordable system with a decent number of options.

I haven't decided what type of bulb to use yet but it should leave our options fairly open.

Any flaws in my thinking?

Posted By: DamonHDWe are using this sort of thing which allows lots of ventilation for the lamps:
http://www.argos.co.uk/static/Product/partNumber/4324397/Trail/searchtext%3EGU10.htm

"•Bulbs required 6 x 50W GU10 halogen (included)."

Gosh! I'm sure that DamonHD isnt running 300W of halogens in each room, but I wonder how many other punters just fit all the supplied halogens and blaze away?

Even when fitted with £50 of LEDs/CFLs it will draw about 50W.

Better than recessed downlighters though. I find that downlighters light 'down' (duh) so the floor is lit but the ceiling is dark, this gives quite an oppressive feel and makes the room feel 'smaller' somehow. My family solve this by turning on loads of table lamps.

I should clarify that we have the 'eyeball' type adjustable downlighters. These have a gap between the 'eyeball' and the fixed bit, through which the wind blows. I was thinking of going back to traditional dangling pendant fittings with 'ordinary' bulb-shaped CFLs, the supermarket "100W replacement" ones. Is this wise?

> These have a gap between the 'eyeball' and the fixed bit, through which the wind blows

I'm sure I'm not the only one here that wonders if that could be a bit of a bigger problem, especially in a new build.
:-)

Posted By: SprocketI'm sure I'm not the only one here that wonders if that could be a bit of a bigger problem, especially in a new build.

Depends where your air tight layer is. Part of my reason for going for a warm roof design as these holes do not matter (edit - except for sound transmission).

http://www.tenmat.com/Content/FF109 Downlighter Covers

These will save you the trouble of rolling your own!

> fire rated fitting

Need to be careful about this. Many folks misunderstand it.
The regs are not about heat from lamps causing fire as many people think (tho that sounds like a good idea). They are about retaining the integrity of the floor (to the level above) if there is a fire. The idea is that the floor, which might be an exit path for people upstairs, retaining it's integrity (both to contain the fire and support people exitting the property).

I believe the BRE has studies showing that multiple 80mm holes for lamps do not seriously compromise the integrity of the floor timbers in a fire situation but this is recent and not common knowledge (ie. wrt building inspectors) so there is still often an expectation that firehoods be fitted. ie. As we know bulding regs inspectors, it's not worth arguing, if it comes up or might come up, just do it.

You are a bungalow. There is no exit path upstairs.
There could still be a minor argument about integrity of roof (ie. not falling on fleeing people below... this has been applied to PV installs recently too I think).

All that said, it is a good idea to put a little (it doesn't need much) space in the insulation around your LEDs to help them run cooler. And it is a good idea to keep it reasonably airtight so draughts in your roof void don't take heat away. I think the small enclosure route you are looking at is sound but only you can balance what trouble that is costing you against the potential heat loss (vs eg. just peeling the insulation back a bit). We all love to save a few extra watt/hours but it's probably rarely actually worth the trouble we take - we're just a bit obsessive. If you work out the heat loss from lack of insulation over 22 small holes it might be surprisingly small (I only said might - I haven't worked it out).

My name is Andy and I'm an ecoholic.
I've been eco-free for two weeks now and I'm still having difficulty coping.
I come here for help and support.

Sprocket wrote: They are probably something like this:-
http://uk.rs-online.com/web/p/visible-led/6935167

That data sheet says the warm white makes 47L/W typically.

I was also sceptical that a bulb made from multiple 5050 LEDS would perform but I figured the price had fallen low enough to risk trying them. So in late 2011 I replaced an array of 230V 50W Halogen GU10s with LEDs based on 20-24 of the 5050 LED die (two different makes). I reckon that overall the light level in the room went up slightly compared to the halogen (Remember 230V halogen are not as bright as 12V halogen). I've not had one fail yet. I paid around £7-£11 each. Very happy and the price has fallen since I got them.

I've also put one in a totally sealed IP67 downlight fitting in the main bathroom as a torture test. Obviously the bathroom lights aren't used as much as the kitchen but this fitting provides virtually no ventilation for it.

Posted By: Sprocket>Would it be cheaper+easier just to buy a lot of baked beans and put the cans over the back of the fitting and then pile the insulation back on top?
Mind you I do understand the usefulness of a good excuse to potter with steel and tools for a few hours.

I've also heard of biscuit tins and terracotta flower pots being used for the purpose.

I think venting is a bad idea from the heat-loss pov: it would be terrible for us since we have lots of air leakage between floors.

Is there any lateral approach that could be used where ceiling bars (etc) could not be used, such as wall uplighters or floor-standing standard lamps, or a tank full of (EST-approved) sharks with laser beams, etc?

Rgds

Damon

Posted By: chuckeyP.S. any one up for rolling 21, 45mm diam tubes

cut a bit off a scaffold pole?

Posted By: Sprocket> Remember 230V halogen are not as bright as 12V halogen

I don't get this. Why not?
Isn't it jut a matter of however many watts into a piece of hot metal?

A 50W incandscent takes 50W from the mains and turns it into about 1W into light and 49 W of heat. Apparently 12V are slightly more efficient at turning power into light than 230V. No idea why.

Interesting discussion but it has begun to go around in circles!

As DamonHD said on 2 July: "for MR16-style halogens the lower voltage versions had the higher luminous efficacy due to the more compact filament."

Compared with a 12V bulb, a 230V bulb must have a filament which is longer, thinner, or a bit of both, to achieve the necessary resistance. I take your point, Sprocket, that one piece of tungsten at 2700K puts out the same spectrum as another - hence the same proportion of visible light to total radiated power. But heat is also lost through conduction (through the filament supports) and convection (through the gas filling of the bulb). These depend on the physical configuration of the filament and affect the bulb's efficiency. I know that's not a full explanation but perhaps helps to explain the very visible difference in brightness between 12V and mains halogen bulbs.

I think it's no coincidence that halogen bulbs first became popular in car headlamps, which run at 12V and can therefore have nice fat vibration-resistant filaments.

Posted By: fostertomDespite the comments, on reflection I think that http://www.aurora.eu.com/ProductPages/LampProductDetails.aspx?g=7822&c=&b=136&oc=84 are prob a gd deal for now - tho not state-of-art, are affordable, very shallow depth, cool running, IP54, swivleable or fixed, sparkling effect unlike CFL equivalents, and lm/W as good as any CFL. Ours are being installed today I think - will see the effect next week.

Posted By: Sprocket the Aurora LEDs that FosterTom pointed to are _much_ brighter and nicer light quality than the 5050SMD bulbs IMHO. They also are ventilated/heatsinked and run fairly cool - they have been proerly designed.

Seen them installed in the finished rooms - absolutely cracking - sparkling without harshness, dimmable.