They are so on and off! I bought a ceiling light for my daughter's bedroom with around 6 halogen (20w) in it. When you switch it on, you are lucky if 4 of them come on. If you fiddle with the rest they usually come on eventually, but once switched off, you are back to the same scenario with at least two not working when you flick the switch. In the bathroom I have 2 over the wash basin. One is fine, rock solid, the other comes on if it feels like it. Can anyone explain why this is to me? is there an answer? Sooooooo tedious. I think I'll go back to a single 150 w bulb till they are impossible to find.
There's a really bad batch of Chinese 20W bulbs doing the rounds (assuming 12V?). It's not a problem with the bulb pins or fitting holder contacts (although some fiddling can get it lit again), it's a fault in the bulb itself, where the filament is badly spot welded to the connection wire inside the glass enveleope. Heating and cooling exacerbates the problem until failure. Aldi are doing packs of 20W spares at the moment.
OK, six times the likelihood of a problem then. My MIL has them in her kitchen and she has the same experience. I have never been keen on these sort of fittings - seem more like "style" than beneficial. Time to replace with a good CFL.
There's a really bad batch of Chinese 20W bulbs doing the rounds
No it is nothing recent - I've had these lights for about 3 years now, and daughter has been at uni in this time which is why I maybe haven't raised it before. Not down to chinese bulbs.
I'll assume 12v, as these seem to give most trouble....
At 12v the current is close to 2amps and the contacts of the lamps socket can overheat and become poor/intermitant. Nudging the lamps in the holders often overcomes the poor contact for the duration that they are still turned on, but as they cool the contact goes bad again. In which case replace the sockets and affected lamps with new.
2nd possibility...
If the filament burns out, you can often tap the lamp and get the filament to make contact again for the time they remain on, the fix is new lamps.
3rd possibility...
If the 240 to 12v transformers (SMPSU) see no load at switch on, they can shut themselves down. This might apply to both of the above scenarios.
Lampholders is always first place to look , they run very hot indeed, misalignment of lamp pins, arcing on the pins or thermal expansion can often lead to problems.
12V MR16 is only troublesome with things like misaligned lamps in their holders, if you spend more than a packet of 10 cigarettes on the trafos they tend to be very reliable. GU10 , so often changing lamps that age related problems never have time to surface ;-)
Consider not using Halogen all together. They have a short lifespan and use too much energy. LED lights can work as a straight replacement using 1/9 the power. Compact Fluorescent Lights exist the the same size using 1/5 the power. References:
Matthew creditable and nicely presented web site and calculator but like your above figures , missing a vital piece of information, actual useable light output.
"LED lights can work as a straight replacement using 1/9 the power."
Unfortunately not even close, LED is currently almost never a `straight replacement` for halogen lamps, there getting better on an almost weekly basis but having worked with LED sources for more than
10 years, they still are not a straight drop in replacement for a 50W
12V MR16 or even a GU10 MR16.
LEDs used in the right way , with an understanding of their advantages and limitations are great and offer possibilities not possible with any other light source.
What they don`t offer is a universal drop in replacement fo all other forms of lighting, have to deal with people who have been oversold LED lighting , at not inconsiderable expense, that dosen`t do what they were sold on it would do.
"Compact Fluorescent Lights exist the the same size using 1/5 the power."
Closer but again missing out quantity of light delivered on task, original poster has problems with MR16, 50mm diameter, reflector lamps. Compact fuorescent, some of them are actually compact cold cathode which isnt as efficient as compact fluro, lamps in this style have awful real world efficiency, the lamp is folded so much to fit in the space that it obscures a large amount of its own output, they really aren`t very good.
Lies , damned lies and statistics is still as true as it ever was.
Also, LEDs 9 times as efficient as halogen lamps sounds like a tall claim to me. Halogen lamps used for lighting mostly achieve 15-21 lumens/watt. 9 times 15 is 135, and I have yet to hear of an LED on the market that efficient, except for extreme of high end white ones when they are seriously underpowered (like 50 mA for ones with 1 mm square ballpark chips, rated 350-1500 mA). 80-100 lumens/watt sounds to me high side high end for LED lighting products. Last time I checked out results of D.O.E.'s "Caliper" program (November 2008 or so), high end was 60's lumens/watt and few products got past the 40's.
Most CFLs achieve close to 60 lumens/watt. Highest I have heard for one consuming less than 45 watts (including ballast losses) is 70 lumens/watt for Philips 25 watt "triple arch" SLS model.
CFLs in reflectors also have wider beam spread and often lower percentage of light within the beam than incandescent/halogen reflector lamps have. The larger light source size makes the light harder to control unless a similarly larger reflector/optic is used.
I agree and maybe a little and-then-some!
CFLs and most white LEDs are more efficient than incandescents and halogens, but exaggerated and/or excessively-optimistic claims of degree of improvement appear to me to be common. Such excessively optimistic and/or exaggerated claims lead to disappointment, and to skepticism and distrust of new lightuing technologies, especially if marketed or manufactured by anyone not having had a solid reputation in lighting for at least something like a decade or two.
One reason why there are no "real" drop-in replacements for
50-watt MR16 lamps is that the MR16 form factor does not provide enough heat sink area for any current-generation LED that creates as much light as a 12-volt, 50-watt halogen lamp.
There are LED-based MR16 lamps that replace 20-watt halogen MR16's because they have lower power dissipation requirements. These are indeed more efficient than the equivalent halogen, but certainly not by nine times! About twice last time I checked.
Same problem with bigger lights, lot of cheap LED PAR 56/64 cans,type of stage light for uninitiated, use the 56/64 shells because it is a convenient low cost housing for what is really a completely different type of light, light output from a 30W LED PAR64 really isnt the same as 1KW tungsten one ;-)
MR16 is big target for all sorts of retrofit hokum,CFL GU10s being prime example, LEDs not being immune, but there are some great MR16 format LED lamps just not realistic to market them as `drop in replacements`.
Going down to MR8 LED actually makes a lot of sense, halogen MR8s look pretty but aren`t very efficient, format fits single big LED and heatsink very well though.
People get sold on lighting being completely retrofittable even with the most inappropriate original schemes, sometimes its kindest to tell clients that proper refurbishment is what they need, not a pile of dubious `drop in replacements`
There is another angle to get folks confused. Stage lights are intended to be used with filters. Some of the deepest colors run about
5% transmition, and many of the paler shades are only 70%.
I'm now seeing marketing claims based on the filtered output of PARs.
*IF* all you want to use is the narrow range of deep blues,. greens and reds then LEDs are perfect.
(Side issue ETC a major theatrical lighting company just bought Selador, an LED fixture maker that specializes in useing 7 colors of LEDs to widen the pallet. If you're in theater this is major news.)
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