So I have light bulbs that say “60 watt equivalent (in terms of light emitted, I’m assuming,) but 40 watt actual usage (of energy consumed?)” What does this mean?
Is it safe to use such light bulbs in a 40-watt lamp, since they only actually USE 40 watts?
Or does the fact that they emit the more powerful light of a 60-watt bulb make them still just as much of a fire hazard as plain sticking a 60-watt bulb into a 40-watt lamp?
What kind of bulb is that? CFL typically use about one fourth as many watts as the brightness-equivalent incandescent bulb. (I.e., a 60-watt-equivalent CFL would use about 15 watts or so.) LED bulbs are in the same ballpark, or maybe use even less.
What kind of 60-watt-equivalent bulb actually uses 40 watts?
The OP was having the trouble of whether that meant 60 Watts of melting power, or 40 watts of melting power…
Its 39 watts of melting power… basically the 60 watt standard incandescent bulb produces about one watt of light, and 59 watts of HEAT …The light is not signficant, its the heat that does the damage to the light fitting, also the wattage of course correlates to a current limit … so obey the wattage even if you think you have dealt with the heat problem. (eg you didn’t put the lid on so the heat is escaping ? well maybe the device has a current limit ! ) but no matter, lets measure it in watts…
So the 40 watt halogen incandescent, or the 10 watt CFL or 8 watt LED makes about one watt of light… the rest of the power is wasted as heat… that means LED is still very wasteful, just far less wasteful than incandescent.
While it is true that LEDs and CFLs put out less waste heat than old fashioned incandescents, LED and CFL bulbs also have their heat concentrated more towards the base of the bulb than an incandescent. Sometimes the wattage rating is due to heating the lampshade or glass in the fixture around the bulb or something, but other times the rating comes from potentially overheating and damaging the base. Depending on how the base is oriented and the airflow around it, etc. you can sometimes overheat the base with a bulb that puts out less overall heat just because the CFL and LED bulbs concentrate their heat more towards the base. An incandescent that puts out more heat may not overheat in the same situation as the heat may be spread out more away from the base where the airflow and heat dissipation may be better.
In such cases, you are much more likely to ruin the lamp than to damage the fixture. LEDs and CFLs put out much, much less waste heat - even in the base - than do incandescents. But, they have electronics in their bases, and will be damaged by poor ariflow.
With incandescents, at least (which includes halogens), it isn’t a matter of some of the energy being light, and some being heat. It’s all heat, and some of that heat happens to be light. The light portion is insignificant for heating the fixture because it’s light, but just because there’s so little of it compared to the nonvisible portion.