LED energy saving bulbs for mains/halogen fittings

Hi All !

I'm having some down lights fitted in the ceiling of a loft area and just realised how expensive to run about 10 of the low voltage (transformer down to 12 volt) halogen bulbs will be - they mostly appear as 50 watts each - that's a lot of power !

Then there are the mains versions of the halogens - but still little in the way of power savings - but why on earth does anyone now bother with the transformer versions of these down light fittings when the mains halogens are available ? Aren't the transformers troublesome?

Enter the world of cheap LED lamps that fit into the mains versions of the down lights fittings - are they called GU10 ? Is this correct? Anyway these LEDs look promising - but what would the light output be like? I am considering the Omicron Energy Saving LED Lamp OMC0025, Colour:6400k, 500 Lumens, 24mA - these apparently use a mere 1.3w each and currently cost only =A31 each.

Can anyone help with all this ? I am utterly confused and out of my depth.

Thanks, Tom

Reply to
Tom
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Where can you get those?

12V halogen lamps are AC, 12V LED lamps are DC.
Reply to
Onetap

LV halogen has all the advantages over mains, other than needing a transformer

6400K is hideous, and the CRI is poor as well.

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Reply to
NT

12V MR16 LEDs are AC (or DC).

The OMC0025 looks like it's a GU10 format, not MR16.

The light output above is obviously a lie - no one has invented an LED that efficient, even in laboratory conditions. Assume the light output will be about the same as a 1.3W halogen, and you probably won't go far wrong.

Reply to
Andrew Gabriel

Use 20 watt ones. You'll hardly notice the difference.

Reply to
Dave Plowman (News)

Well, you could put 20W bulbs in instead and get a 60% reduction in power dissipation.

Don't forget that in the winter that's 10 x 50W = 500W of space heating you don't have to provide by other means.

In fact, it's the other way around. The mains version (GU10) has a very thin filament and consequently in many cases a *very* short life. Decent transformers are not a problem if you can get 'em (often pot-luck). Usually even when you buy a low-voltage fitting from a shed, half the bulbs they supply don't last 5 minutes. Put decent branded bulbs in and it's all good.

What Andy Gabriel says.

Reply to
Dave Osborne

They sell them at Robert Dyas.

Reply to
Tom

The packaging claims 500 Lumens - the bulbs have 20 LEDs in them - is this not possible? I did think the low wattage looked too good to be true (1.3W) !

Thanks for the replies.

Tom

Reply to
Tom

Whats the use, office, bedroom, home theatre, gym...?

Sun delivers a bit under 2kW/m^2 in summer, lighting like heating is anenergy intensive activity.

Covered by other posters and repeated rants by myself in archives, LV halogen is much better and pennies more expensive at install. Mode transformers are gold standard some cheapies almost as good some terrible.

Cannae change the laws of physics, a 100% efficient lamp would attain

236 lumens out for 1Watt of energy in. These Omnicrons have beat the limit of Stokes Efficiency and are hitting over 386 l/W for a quid each the worlds energy crisis is solved.

Confusion is very deliberate on behalf f the marketeers.

Depends on use of space , perhaps concealed fluro might be appropriate for general lighting with additional task and/or mood lighting.

Heat load in loft space may be significant in summer.

Bit more info on intended use might get better suggestions on solutions, just stay away from GU10s ;-)

Cheers Adam

Reply to
Adam Aglionby

The key parameter is "lumens per watt".

Cheap non-quartz halogen is likely to be under 20 lumens per watt. Well under in some cases.

Latest LED technology can comfortably exceed 100 lumens per watt.

Do some Googling because there's a lot of information out there.

You need to be looking at a 3 or 4 watt LED to have a chance of delivering a useful amount of light.

You then need to consider the structure of the light as well. I can tell you empirically that the 3 Watt 48SMD designs readily available on eBay are pretty good. NO WAY do they meet their claims to be as brigt as 50 Watts Halogen, but they certainly compare with 20W.

Reply to
Vortex4

But why one would put 500W heating in downlighter holes in a loft ceiling ? Most sensible people would put it where the heat was needed.

This "lightbulbs as a useful heat source" argument is often trotted out, but has never struck me as sensible. Is it efficient to place space heaters at the highest point in the room?

Reply to
OG

Nor me. Yes there will be a bit of extra heat in the room but more or less negligible in the scheme of things. Lets keep it simple an ignore really lossy things like windows and doors and have a 4 x 5 x

2m room so total surface area of:

= 2 * (4*5 + 5*2 + 4*2) = 2 * (20 + 10 + 8) = 2 * 38 = 76m^2

Say 100W/m^2 heat loss = 7,600W is a hundred watts from a lamp really significant? Open the door and more that that disappears through it...

Reply to
Dave Liquorice

Until its summer, the Sun requires pulling the blinds and have a couple computers running, another 1/2K of heat is really not whats needed...

Cheers Adam

Reply to
Adam Aglionby

How much? ? ? That might be reasonable for a greenhouse, but not for a room

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Reply to
OG

Actually, it was tongue-in-cheek on my part. Should've done a ;-)

Reply to
Dave Osborne

I did pull the figure from the air but

9" solid brick wall with 23C across it (-3 outside 20C inside) is 23 x 2.2W/m^2 = 50W/m^2 so with air changes as well 100W/m^2 total heat loss is not that far from the mark.

A modern hermetically sealed rabbit hutch with 11" brick/block cavity insulated with the same temp difference is 13W/m^2 or just over 1kW, The 100W lamp is still only 1/10th of the required energy input and do people really use 100W lamps? I find them far to harsh, 60W perl is much kinder on the eye.

Reply to
Dave Liquorice

I'm having some down lights fitted in the ceiling of a loft area and just realised how expensive to run about 10 of the low voltage (transformer down to 12 volt) halogen bulbs will be - they mostly appear as 50 watts each - that's a lot of power !

Then there are the mains versions of the halogens - but still little in the way of power savings - but why on earth does anyone now bother with the transformer versions of these down light fittings when the mains halogens are available ? Aren't the transformers troublesome?

Enter the world of cheap LED lamps that fit into the mains versions of the down lights fittings - are they called GU10 ? Is this correct? Anyway these LEDs look promising - but what would the light output be like? I am considering the Omicron Energy Saving LED Lamp OMC0025, Colour:6400k, 500 Lumens, 24mA - these apparently use a mere 1.3w each and currently cost only £1 each.

Can anyone help with all this ? I am utterly confused and out of my depth.

Thanks, Tom

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Hi Tom, Whilst I've not got experience of GU10 LEDs, both types of low voltage MR16s that I've had have exhibited varying degress of interference with FM and DAB radios in the house i.e the lights work but the radio signal degrades to a level that is unlistenable to. Turn the lights off and 'Hey Presto' the radios work again. GU10 may not be a problem but I thought I should mention it. That said, the 4 Exergi 4W MR16 bulbs I've got in the bathroom are great - but don't install them near a radio.

Cheers, Keith

Reply to
KD

Are you talking about some form of 'CFL' MR16? Proper MR16 are tungsten and won't cause interference. Nor should the power supplies for them.

Reply to
Dave Plowman (News)

They're LED lamps. About 20 quid a pop.

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may be interference from the internal regulator gubbins. I'm more inclined to think the external (probably switched mode) PSU does not like having such a low load. I'd try powering one of these lamps from a car battery and see if there is interference then.

These

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work fine for me with LED.

Reply to
Vortex4

Thanks Vortex4, I'll give those a go. To add some confusion (I'm not a great DIYer) here is the sequence of events for previous LEDs....

a) Bought some Deltech MR16 LEDs off ebay. I took the chance of not replacing the original transformers. Interference from the bulbs caused ALL radios in the house to lose reception. b) Replaced all of the appropriate transformers with 12V DC LED drivers. This did not solve the problem. c) Contacted Deltech who have said that there may be a problem with their MR16 (but not GU10) LEDs. They're working on it and will give me replacements when fixed. d) Took the plunge and bought some Exergi LEDs. Fitted those and the interference went away. e) Bought 4 more for the kitchen ... installed these without changing the original transformers and there is interference on the kitchen radio.

I have requested to return them but since you've been so kind as to post a link to more affordable transformers than I've previously seen, I've just ordered 4 LTYT70s (the others were out of stock) and I'll give that a go first.

Cheers, Keith

Reply to
KD

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