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120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

(OP)
Almost a trivial question, but if I felt completely comfortable with my instinctive answer, I would not ask the question in public.

If a "standard" US UIL-rated commercial lamp socket (overhead fan, overhead light, or desktop lamp) is rated for a "classic" 60 watt bulb - assumed that is the stamped "maximum light bulb" that should be installed in that fixture, then what rated LED bulb can be safely used in the same socket.

Obviously, the current limits for the original rating are based on a classic incandescent light bulb, which emits 5-15% maximum energy as visible and useful light. Some of the remainder is I^2R losses caused by the electric current. The rest is heat energy that MUST also be dissipated. And, clearly a 60-watt equivalent LED bulb can be used in a 60 watt incandescent socket.

But the newer LED bulbs are much more efficient than the old ones, and emit more lumens that an old LED bulb with much less current, and many times the light output for a much smaller current than the original incandescent bulbs the UIL was using for their heat standard.

So, given the current and I^2R losses are much lower with a newer LED bulb, and the heat losses are much, much less with a newer LED bulb, is it prudent to use a larger 75 watt equal or 100 watt equal LED in the old 60 watt socket?

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

That "equivalent" is about light output. The socket 60W rating is based on 60W of thermal/electrical load. As long as you don't exceed 60W of load you're fine. That rating has nothing to do with whether or not you'll blind yourself, just that you won't ignite the socket.

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

Don't look at the "equivalent" wattage (the wattage of an incandescent with equivalent lumen rating), look at the actual wattage of the bulb in question.

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

An "equivalent" 60W might only be 10W, give or take. Assuming you could get them cheaply, you could put a 500W+ "equivalent" LED bulb in that same socket and be safe (at least from the socket's point of view).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

Look at the heat radiated by the light source.
60 true Watts of LEDs, not equivalent Watts, will probably be cooler than a 60 Watt incandescent bulb.
Enough LEDs to come close to the heat loss of a 60 Watt incandescent bulb will be very bright.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

(OP)
Your comments reflect what I thought were the circumstances.
An "over-equivalent" wattage LED bulb can be used in a UIL incandescent socket, if prudently evaluated for the actual heat load of the new bulb.

My thank you's to all who read, who responded.

RE: 120 VAC Light Sockets: Proper Heat Load/Current Rating for LED bulbs vice Incandescent?

The fundamental problem with LEDs is that while they put out considerably less heat they must operate at greatly lower temperatures than incandescents.

They can not get very hot without quickly failing. The working delta of LED heat rejection systems is pretty darn low so a big material and design effort is needed to remove the heat. But, small wrongs in fixtures results in breaking the cooling designs and subsequent over-heating.

Always look at a LEDs cooling design and try to asses how it will perform in the fixture you want to use it in. If the fixture will prevent clearly needed convection or alternatively, blocks radiant cooling paths don't proceed or you'll just be wasting money and creating inconvenience and annoyance.

Remember too that salable lamps only need to not cause fires (UL) not actually last more than five minutes.

Keith Cress
kcress - http://www.flaminsystems.com

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