LED bulb

[winnie]

I was simply explaining why fixtures may say "60W incandescent" but how a 17W 100w filament equivalent LED may not survive in it.
60W filament lamp gets rid of most of the heat by infrared, which is radiated out, or absorbed in the reflector. The reflector in turn gets blistering hot.

A 17W LED lamp may put out maybe 5W of visible spectrum, but the other 12W has to go somewhere and much of that has to be conducted away the heatsink.

The amount of heat rejected by a fialment bulb as conducted heat is in single digit %.

Your numbers seem plausible.

Consider a 100W incandescent bulb. It might put out 1600 lumen. You are suggesting that somewhere between 1 and 9 W of heat are being conducted from the base of the bulb to through the lampholder. That sounds plausible to me; some small amount of heat will be conducted down the lead wires to the filament, and some small % of radiation will be intercepted by the bulb base and then conducted through the lampholder.

An equivalent LED bulb might require between 14 and 18 W of electricity. Your 5W of visible light photons seems about right; though if you have a poor spectrum the number could be higher. So with the LED you have some 9-13W of heat being carried away, much through the base and lampholder.

-Jonathan

 

[Flicker Index]

Your numbers seem plausible.

Consider a 100W incandescent bulb. It might put out 1600 lumen. You are suggesting that somewhere between 1 and 9 W of heat are being conducted from the base of the bulb to through the lampholder. That sounds plausible to me; some small amount of heat will be conducted down the lead wires to the filament, and some small % of radiation will be intercepted by the bulb base and then conducted through the lampholder.

An equivalent LED bulb might require between 14 and 18 W of electricity. Your 5W of visible light photons seems about right; though if you have a poor spectrum the number could be higher. So with the LED you have some 9-13W of heat being carried away, much through the base and lampholder.

-Jonathan

Some "filament LED" bulbs also use helium, or hydrogen blend gas inside the envelope to improve convection cooling. Perhaps you have heard of synchronous machinery used as an infinitely adjustable capacitor to create MVARs on the grid. Similarly, such machines are sometimes filled with hydrogen gas for better cooling.

Filament bulbs are gas filled for a whole different reason. Absolute vacuum is ideal if it wasn't for controlling filament evaporation, but inert fill gas serves as a packing atmosphere to keep the filament from evaporating while being as least thermally conductive as possible. There is a journal article out there somewhere giving a detailed break down, but I couldn't find it now.

Watts radiant emission per watt input efficiency of an incandescent lamp is considerably higher than LED.

There's also lumens per light watt too, because lumens is a human stimulation value. You could have a 50% LED element that's making half a watt of light for each watt of electrical input and they're 50% efficient regardless of the color of light, but the lumen value varies, because of human eye sensitivity curve.

LEDs can't handle temperatures high enough to radiate away the other 50%, so the heat has to be conducted away into a larger surface area for cooling.

 

[Flicker Index]

It seems you're trying to compare a 25w I can to a 25w LED, and then compare a 60w I can to a 60w LED only on the basis of heat per watt

That's disingenuous, and you know it.

A 60w LED bulb most likely isn't even going to fit inside a fixture meant to enclose a 60w incandescent bulb. And you know that, too.

It's okay to say "my biased opinion is that LEDs suck"

It's not okay to talk in circles, then try to pretend it's a genuine scientific position which sprung from concern for the lighting industry

Actually, it's not uncommon. Suppose your desk task lamp says "40W A19 bulb maximum". Most reasonable people understand that they can't put in a 100W bulb to get more light, however they often believe they can put in a 17W 1600 lm LED lamp. Many lamps, even those specifically rated as non-dimmable will have an internal dimmer controlled by thermostat but it's almost never documented on retail package. If you monitor the input power, it will go up slightly after a few minutes as it nears, then thermostat kicks in to maintain constant heat sink temperature. If you blow a fan at it, the input power will gradually return to normal. Many of LED ballast boards already contain 0-10v dimmable input anyways, so that input is often utilized to control the ballast in a closed loop mode (constant heat sink temperature) and do so smoothly without a noticeable bump. When done in this manner, the lumen drop is very smooth and often go unnoticed, thus avoids unfavorable product reviews and product returns.

Those without LED / ballast fry-out protection will start to give off burnt plastic smell and depending on the ambient temperature and level of ventilation natural to that fixture, it could fry out within a matter of few hours to 100 hours or so.

"open fixture" means something like a traditional table lamp or wall sconce that's open on both ends. Cupped fixture that's closed, or significantly closed with just a few vent holes are considered "semi-enclosed".