Can I take it that where a lamp or shade states a maximum wattage, this is for incandescent bulbs and any LED will be okay (on the basis that LEDs use so much less power), or is the light intensity likely to be an issue liable to cause fading?
Remember that LEDs don't like the bases containing the electronics to get too warm (this will shorten the life). The devil is in the detail.
To a first approximation, if it's rated 100W filament lamp, it will be suitable for 100W equivalent CFL or LED, even though these actual wattages are very different. However, it depands entirely on the ventilatiom, and if you are happy for a shortened lamp life, which is a comprise I'll often take.
Scott explained :
An LED is very susceptible to damage from its own heat build up, much less of an issue is likely heat damage to the shade it is in. If the shade allows good airflow and cooling of the LED, likely it will not be a problem.
yes
no. LEDs are not heat tolerant.
you jest
Any LED is fine if the fitting is open & well vented. In a closed fitting, LEDs of same light output have a greatly reduced life due to overheating.
NT
That nicely sums up the issue. The incandescent lamp wattage rating for any given lamp shade or luminaire is based on how much heat it can safely handle. Incandescent lamps run at much higher temperatures than any LED can survive (150 to 200 deg C ).
The problem with LEDs is that the LEDs themselves and any fancy electronic ballasts have a maximum junction temperature rating of 125 deg C meaning the whole lamp must be kept a good 30 to 50 deg cooler to establish the required temperature gradient between ambient and the solid state device junction temperatures within (LEDS and switching transistors and diodes) to dissipate the heat generated by these devices.
The older, less efficient 81 LPW LED lamps were limited to the equivalent American based 806 Lm 60W rating and even these only met their claimed 25,000 hours life rating in open reasonably ventilated shades/ luminaires.
Now, it is possible to upgrade those 810 Lumens lamps with the 100W
1500Lm LED equivalent 12W 125 LPW lamps in those very same luminaires because they produce slightly less *waste* heat than the earlier 810 Lumens 10W LED lamps did, meaning they will run just as cool, if not slightly cooler, despite consuming an extra 2 watts for almost double the light output.The main benefit of yet higher efficiency LED lamps is not the power savings they offer but the fact that they can be fitted into almost every standard luminaire or lamp shade with almost no regard to the issue of overheating that afflicted the early low efficiency LED lamps.
Most of the energy savings to be made with lighting were achieved with the CFL generation of energy efficient lamps. Upgrading a houseful of CFLs to today's modern 125LPW LED lamps will offer a vanishingly small reduction in the overall domestic electricity bill.
I'd imagine that depends on the quality of the shade. Don't you think shades are the most pointless things every invented? After all you go for more efficient lighting solutions yet try to block some of the light with a shade.
I propose nice to look at sockets and lamps instead. Brian
One issue I've found a lot of lately, particularly when a BC holder has previously had a filament lamp in it, is plastic break-up. I've had one low energy lamp fall out and smash on the floor as the tiny little bit of metal that is left when the plastic gives up on the bayonet pin holding notch just cannot support a heavier low energy bulb, bends and it falls to the ground. This seems particularly likely if the socket is on its side. In the cases thus far these have been cfls, so a bit of a hazard and lots of broken glass to clear up. Brian
Trouble there is that they aren't very nice to look at, and if you can look at them then they aren't bright enough to illuminate a large area very well. I thought the idea of a shade was so that yuo couldn;t see a really bright bulb and that the light got diffucused by the shade which could also add a bit of colour.
Very helpful. Mind is in a globe (bathroom light) but it is quite a big globe. I won't go overboard with output..
Very good points. I shall buy Philips and not one from the pound shop.
And instant start and arguably better colour rendition.
They diffuse the light. I don't want to look at a bulb, much too bright.
I have a Philips Hue bulb in the light beside my bed: a bare fitting in a table lamp, with no shade.
The light part of the bulb gets barely warm. The base gets fairly hot: it's bareable for 10 seconds but after that it starts to become a bit too hot to tolerate.
And that's with no shade around it, so best-case cooling. It's rated 10 W /
70 mA / 810 lumen. And that's for maximum brightness at a fairly neutral white.
Some shades help cooling by creating convection like chimneys do.
Exactly. The purpose of a (translucent) shade is to increase the effective size of the illuminated area (and maybe to direct the light a bit more from being omnidirectional) so it's more diffuse and less of a point source. That's why in the days of tungsten bulbs, they started frosting the inside of the glass so the whole bulb was a uniform brightness and you didn't get a thin filament of brightness which tended to leave more of an after-image on the retina if you happened to look at the bulb.
And this is where LEDs are really bad in spotlights you end up with a bright spot on the wall, OK if that's what yuo want but most want even illumination throught the room.
Short engineering dissertaion on heat dissipation.
What kills incandescent lamps is "hours on".
What kills lampshades is peak temperature. That why they have lamp wattage ratings. 90% of an inmcandescent is heat so to a first approximation a '60W lampshade' can take 60W of heat in its middle without going brown or catching fire..
What kills LEDs is the product of life and of temperature. The hotter they run the shorter they run.
However most LED *CHIPS* will stand to run at 100C or more.
What this means is that *NO* LED is going to scorch that lampshade. To get 60W of heat you probably need 80W of LED, and that probably will not fit in the lampshade. And would blind you!
I've just grabbed a candle LED that is about 40W equivalent, and its about 40C. That is par for the envelope of a LED bulb.
Ergo the only critical factor is whether the lampshade will overheat the LED.
Frankly if it's designed for an incandescent the answer is hell no!.
I've even put LEDS in enclosed cooker hoods and fully enclosed luminaires and they have been FINE. For several YEARS.
As usual tabbypurr is pontificating from limited armchair theory and zero real understanding.
so far so good
yes, with limited use. You've got 15k or 25k hour life lamps, a year on 24/7 is only 8760rs. If you're willing to live with much reduced life, great, go for it.
whoosh.
NT
I look cool in shades :-D
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