Do the maximum wattage warnings on (oldish) light fittings only apply to incandescent bulbs? I assume it's because of the heat melting the fitting?
So I can put a 100W equivalent LED in a light fitting marked "60W max"?
Yup, its actual watts that count... so a 13W LED counts as 13W regardless of what its incandescent equivalence is.
Maybe, maybe not.
If its well ventilated then yes as the LED will run cooler and everything will be fine.
If its not well ventilated the LEDS while not getting hot enough to damage the fitting may well get too hot to be reliable. Incandescent lamps are happy at a few hundred degrees, LEDs are not.
I doubt if huge will read this as he his one of the idiots that killfile people that can help.
And presumably, because of their much greater efficiency, you could put a
200W or 300W LED lamp into a "max 100W" fitting, even though its tungsten equivalent will be much higher, because the amount of heat (as opposed to light) of a 200 or 300W LED lamp may be less than for a 100W tungsten lamp.Mind you, a 300W LED lamp would probably be enormous (because of the finite size of the large number of LEDs that it would comprise) and would sear the eyeballs of anyone who looked directly at it :-)
Good, that's how I've been interpreting it!
no, a 60w max fitting is safe for 60w max, regardless of bulb type. 60w of LEDs would produce quite some light - equivalent to what, 800w tungsten?.
60w of LEDs however would overheat & die in most 60w rated fittings.NT
Kewl, that makes sense. Thanks.
And that's conservative... Incandescent lamps run at ~2% efficiency, so a "max.
60 W" fitting is rated to not overheat when roughly 60 Watts are dissipated inside. LED lamps are more efiicient, so more Watts leave the fitting as light. Sooo, 10-14% (wikipedia)... er, say 70 Watts.Not as much difference as I thought...
Thomas Prufer
The lamp fitting would probably survive but the LED psu has to stay well below 100C to avoid the capacitors drying out prematurely. This generally requires some air movement past the body of the lamp.
This means that putting LED 60W light output aka 12W input power bulbs into sealed glass bowl type fittings shortens their life considerably. A traditional filament bulb would be perfectly happy in there.
I have one 150W equivalent corn on the cob LED bulb which isn't all that much bigger than a pygmy bulb (though about twice as long). It is an ideal compact inspection lamp since it doesn't get mad hot.
High power LED lamps tend to be in E40 fittings eg this 60W
(take light output claims with a pinch of salt)
En el artículo , Huge escribió:
Yes, it's thermal watts, not electrical watts.
If you can find a 60 watt LED let me know! I suppose they might be used in streetlights.
Probably not - while far more efficient, ultimately much of that energy is still going to come out as heat in one way or another. (and as power goes up with LEDs heat becomes ever more of a problem)
Indeed:
and less if some of the light gets reabsorbed by a shade or is reflected back onto the lamp etc
A light fitting designed to cope with the heat of a 60W incandescent lamp may not necessarily provide sufficient ventilation to stop even a
15W rated LED lamp from overheating (the prime cause of premature lamp failure when using LED replacements in fittings designed for incandescent lamps).However, a more modern 10W 810Lm "60W equivalent" to the higher efficiency USA lamp specification (closer to that of a 75W 240v 1000 hour rated lamp) will likely be ok in a 60W rated fitting unless the design lacks ventilation causing the air surrounding the lamp to act like a warming blanket, raising the temperature of the LED's innards to beyond its maximum limit. LED lamps have to be run at considerably cooler temperatures than an incandescent lamp will routinely cope with.
CFLs have similar temperature restrictions so if you've been using a 15W CFL without suffering premature failures in an existing lamp fitting designed for incandescent GLS lamp types, the chances are pretty good that you'll be ok with a similarly watt rated LED lamp.
That's all fine and dandy as far as the light fitting (luminary) requirements are concerned but the replacement LED lamp will have its own considerations regarding maximum operating temperature limits to contend with. Unless the existing luminary is well ventilated, even a 15W rated
1050Lm LED lamp may well fail from overheating despite only using a quarter of the original incandescent lamp's wattage.The real benefit of the promised 250 to 300Lm per watt LEDs over the current crop of 90Lm per watt LEDs available today isn't the reduced electricity costs but the increased flexibility in use of these new higher efficiency 100 and 150W equivalent LED lamps that can be safely run in an indifferently ventilated fitting originally designed to cope with a 60W incandescent lamp.
I've thought that, but I have a 6.3W LED which gets hot and a 5W one that doesn't; the PFs are rather different - but I can't remember what exactly. With CFLs and LEDs I tend to double the wattage to allow for extra heat, so in a 60W-rated holder I'd not go over 30W. As others have said, high wattage LEDs are rather excessive.
Not true. A 60W tungsten lamp is very inefficient (about 2%) so will produce the same amount of heat as a 58.8W resistor.
However a typical LED lamp is about 10% efficient and so a 60W LED will only dissipate the same amount of heat as a 54W resistor.
As quantum efficiency of light sources increase over time then the actual power dissipation will fall further with respect to the actual power consumption of the bulb.
It is dissipation and not consumption that is the guiding factor.
In the limit with 100% conversion efficiency you could plug a 1MW light source into a 60W holder with no problem, the bulb would remain cold to the touch.
I think in the near future bulbs and holders will need a new rating system to define the actual dissipated power that is produced/can be handled.
Andy
And will survive an envelope temperature typically around 175C. It won't fail until the temperature softens the glass envelope seal.
And will be dead very quickly if its PSU capacitors ever get above 100C. They are very good at cooking themselves to death when used in some unsuitable fixtures designed for filament or halogen lamps.
There has been amazing progress. I have as a demo an original 1970s red LED and modern high intensity one in series with the same resistor. The old one is barely visible and the modern one painful to look at!
Not just the dissipation but the temperature tolerance of the respective devices. A lot of premature failures of LED GU10 halogen replacements in ceiling fittings is because the insulation to protect the building from catching fire needed for halogens kills LEDs.
I think the 13A circuit fuse would limit you to ~3kW.
A 1MW lamp at 1m would be around 100kW/m^2 flux you would rapidly get the ceiling to around 900K or about the melting point of brass. Given 1kW/m^2 sunlight ~ 300K ambient.
It is variable. In free air with convection cooling LED bulbs can handle a lot more power than when enclosed inside a glass globe. By comparison a conventional filament lamp won't even notice.
John Rumm used his keyboard to write :
Because LED's are so efficient at producing light rather than heat, I would rate a 13w LED as around the equivalent of a 4w lamp. The thing is, the LED lamp itself needs to be able to run cool. High temperatures in a fitting will rapidly kill one.
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