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Blog Archive

Thursday, February 17, 2011

GU10 halogen bulbs revisited

Things have moved on since my previous blog regarding GU10 halogen bulbs. To recap, 10 years ago we had our house extended and rewired. We had 40 recessed halogen light fittings installed, the type which runs from 240V main voltage (GU10) not the 12v system (MR16).

While the light is good, and the reliability of the bulbs has improved, they still use a lot of electricity (50 or 35 watt types) and get very hot. In my previous blog I explored the options which were available including first generation LED bulbs and Compact Fluorescent Lights (CFL) in the GU10 size.

That was two years ago , and at that time LED bulbs were not up to the job and CFL's , typically Megaman variety seemed the best alternative. These consumed only 11 watts and give pretty good light from a few minutes after turn on.

I posted a few follow-ups as I tried a few next generation LED bulbs and this post picks up at that point.

In my utility room I had 4 of the Megaman brand CFL GU10 bulbs and these seemed to be taking longer and longer to get achieve full brightness, though initially this had not been a problem. One failed and when I removed it, the bulb was discoloured , with brown marks around the edge and indications of heat stress cracks in the plastic. It also had developed a rattle if I shook it. I took out the three remaining Megaman bulbs, and though they still worked, they too all had the same characteristics of discolouration and cracks. they even all had rattles, though they still worked ! this prompted me to revisit LED bulbs. It also makes me think that the initial promise of CFL long life no longer carries much weight.

I have replaced CFL conventional bulbs increasingly frequently, and I'm guessing that as the prices have fallen , so too has the promised longevity. There is something of a backlash against CFL bulbs , partly due to the high cost of disposal. These bulbs when they fail, should not be thrown away with household rubbish, but recycled at your local tip with other fluorescent bulbs and tubes as they contain small amounts of toxic substances such as mercury.

So I purchased a number of the newer LED alternatives, which still promise long life and low power consumption, and this blog is my findings.

Here is my police line-up of the usual suspects, from left to right we have :

1) a conventional 50 watt halogen bulb, included for reference to size

2) A Megaman CFL GU10 equivalent

3) An LED bulb, purchased at Maplins for around £5. A very early example using a cluster of 24 conventional blue-white bulbs. As per my previous blog, this was very poor in terms of light quality, brightness and reliability. After a year a number of the individual led bulbs had failed.

4) A3 Watt alpha LED GU10 from B&Q, cost around £13. These were mentioned in the previous blog as the first LED alternatives that showed real promise. This uses an array of surface mount LED's behind a semi opaque diffuser. Great light colour though unsuitable as spotlights. immediate full brightness from switch on.

5) A
4 Watt GU10 High Power LED (20 piece SMD 5050, 320 Lumens, 50 watts equiv.) ( QB-1050) (Warm White) @ 11.99 each from SIMPLYLED on the web. These use surface mount LED's which are clearly visible in the picture as yellow blocks. The light is bright and well spread, though a little yellow. I have three of these in a guest bathroom and the light is good, though not quite as good as a halogen.

6) A
3 Watt Interlux™ GU10 Warm White at £10.99 from LEDLIGHTS4LESS on Amazon. these use 3 super bright LED bulbs through a diffuser. the construction is similar to 5) in that the body of the bulb is metal with cooling slots. These are closer to a spot light with good colour and come very close to a 35 watt Halogen. I have 17 of these in bathrooms and kids bedroom. These , while not quite as good as a halogen, give a nice bright instant light source and are my favourite LED GU10 bulb replacement.

I do have a couple of the 12v bulbs (MR16) in shower extract fan fittings with integral lights. While I tried MR16 LED bulbs from both SIMPLYLED and LEDLIGHTS4LESS, they flickered very noticeably. I believe this is due the the 'ballast' i.e the transformer that drops 240v down to 12v. These expect to drive a certain load , typically 20-50 watts. Unfortunately the 12v MR16 LED bulb is 3 watts, and so always check first to see if your MR16 lighting uses ballast power supplies capable of driving a few watts. I will add at this point that both SIMPLYLED and LEDLIGHTS4LESS replaced the MR16 bulbs with extra GU10's with no fuss and both gave exceptional service over the internet.

My conclusion is that while LED bulbs are still quite expensive (circa £10 per bulb) , they are capable of providing good light quality, with instant full brightness, while only using a few watts and staying cooler than a 50 watt Halogen. They are not quite as good as Halogen and I retain some in my kitchen work areas and above some cupboards in my bedroom where the premium light quality of Halogen is preferred,.


Anonymous said...

Nice review. I have just bought the interlux led bulb and this is by far the best of all of the bulbs that I have tried.

valuethinker said...

With £24 Philips 2700K, 40 degree angle, 7 watt LED bulbs I replaced all my 50watt halogens (GU10 fittings).

Light colour is fine (2700k).

Intensity is good, not noticeably less. Angle (40 degree) is a bit tighter.

I calculated my payback, at 13p/ kwhr for electricity (Southern Electric) at about 3000 hours.

For a kitchen lightbulb, we hit payback in less than 18 months. For other lightbulbs, longer than that.

On an NPV basis, against a halogen costing £4 and ignoring the winter heating effect (the waste heat heats the ceiling of the kitchen ;-)), then NPV is c. £80 assuming the bulb lasts more than 12,000 hours.


Anonymous said...

Worth trying Exergi too

Their previous 4.4 W GU10 lamp has a nice warm white colour (fine if you like warm white; I'm seeking a more neutral white which is difficult with LEDs, most of which are too blue or too yellow.)

Exergi are now making a similar but 3.6 W lamp. I haven't tried it yet.

Crystal Clear Headlights said...

Great information. I think I'm gonna try one, too.