1. ## Lamp "ratings"

Okay, I'll start this out by saying I am not looking for guesses, hypatheticals, or probable answers to my question. I'm looking for an answer from someone who knows. I don't mean to be rude, I just am looking for truth, not conjecture.

If you are still reading...thank you.

When a lamp says "60 watt maximum", what exactly do they mean. Are they saying, by the letter of the statement and just as it reads that the bulb that you put in it can not draw more than 60 watts? Or is this some sort of rating based on the amount of heat that a 60 watt bulb gives off, and the unit is insulated to that degree? Likewise, is it more a matter of the load that the wiring can handle?

The reason I'm asking is directly related to replacing incandescent bulbs with LEDs. If a fixture is rated at 60 watts, and you replace it with an LED, if you are going staight by wattage, you could have ONE HECK OF A BRIGHT BULB IN THERE!!!!!!!!!!! But I would imagine that an LED that consumed 60 watts (besides being a budget buster and a blinding light source) would run hotter than a 60 watt incandescent bulb...though I could be wrong about that.

Bottom line, if a fixture is rated at 40 watts do you need to stay with the LEDs that are 40 watt equivelants, or can you go to the 60 watt equivelants? Granted, I know that lumens might play into this. But there might be a very simple watt to watt yes or no answer, or it might be more complicated...

Thanks to anyone that has the answer to this simple, but drawn out question...

2. Hypothetically, I would guess that it probably means…

…never mind.

I have always acted upon the assumption that it has to do with the capacity of the wiring and heat dispersion. So that sets me free to put in a flourescent bulb that has lower wattage but higher output. I have not yet used any LED's.
Last edited by Brian Kent; 02-03-2013 at 9:59 AM.

3. 60 watt maximum? This seems obvious - watts is watts, doesn't matter the bulb. Also, make sure you use it correctly (dry location, wet location, etc).

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It's a simple, but drawn out answer.

The max wattage label on a luminaire (light fixture) is there to advise you of how much heat the fixture can safely withstand. As you know, incandescent bulbs put out a LOT of heat - that's why my daughter could bake a cake in her Easy Bake oven which is heated by a single light bulb.

The labels are typically found on luminaires where the bulb, and hence the heat, are enclosed. Unfortunately, there is no easy way for the consumer to compare the heat output between incandescent, LED and CFL bulbs. However, you really don't need to. A 60 watt bulb puts out about 85 BTU's per hour, an equivalent 13 to 15 watt CFL about 30 BTU's per hour and the equivalent 6 to 8 watt LED only about 3.4 BTU's per hour. Focus on lumens instead, since light is what you're looking for.

There are other considerations besides heat. Incandescent luminaires were designed around bulbs which emit light in all directions. For ceiling lights a properly designed LED luminaire will be much more efficient than an LED bulb in an incandescent luminaire. I plan on replacing all my ceiling luminaires as the selection of new ones designed around LEDs becomes larger and less expensive.
Last edited by Mike Cogswell; 02-03-2013 at 10:23 AM.

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The rating is there for the size of the wires and the heat from an incandescent bulb. Since LED and CFL are more efficient at converting electricity to light then for the same power (eg. 60W) you'll get less heat from CFL or LED. Since CFL and LED are so much more efficient neither of these is much of a concern, but do follow the actual wattage consumed for safety reasons and equivalent wattage for desired light output.

6. Thanks for those answers. So, and this is where I'm kinda going with this... I could, effectively put in a 60 watt LED (which would be about the equivelant of a 270 watt incandescent bulb) and I would be fine...right? That is a LOT of light!!!!!!!!!!!!!!!!!!

7. Originally Posted by Brian Kent
Hypothetically, I would guess that it probably means…

…never mind.
Beautiful, Brian, juuuuust beautiful!

8. Originally Posted by Mike Cruz
Thanks for those answers. So, and this is where I'm kinda going with this... I could, effectively put in a 60 watt LED (which would be about the equivelant of a 270 watt incandescent bulb) and I would be fine...right? That is a LOT of light!!!!!!!!!!!!!!!!!!

Yes.

The watt rating is almost entirely a product of the fixture's ability to withstand heat. An incandescent bulb only turns 1% of the supplied energy into light (the other 99% is heat). Worst-case, an LED replacement bulb might be turning "only" ~70% of the energy into light. Ergo, if you have fixture rated for "60W", you could probably safely install a 200W (or a "900W incandescent equivalent") bulb in the same fixture. Good luck finding one of those

There is a secondary consideration of the current handling capacity of the fixture, but given that we're in the single-digit amperage range, it's likely not a concern.

9. I think this ratio is off, or the lumen output of LED bulbs would be a lot higher.

Incandescent bulbs are about 16 lumens per watt, and the best rated LED replacement bulb is around 64 lumens per watt.

The next round of LED bulbs is supposedly going to be a little better, but the current round is in the CFL range or a little lower in a lot of cases.

On a separate note, in terms of whether or not those max ratings matter, our neighbors had put cans in their finished basement 7 years ago and went above the wattage rating and burned their house. I'd follow the ratings (on a wattage basis).

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The ratings have to do with heat generated by regular light bulbs. I put 100 watt equiv CFLs in fixtures rated for 60 watts all the time.

LED light bulbs still generate heat. Ever notice they all have large heat sinks on them? In my motorhome I replaced some halogen light bulbs with LED light bulbs that have 28 individual LEDs. The new LED bulbs get pretty warm. A lot warmer than I thought they would get. I should have used the version that only has 6 LEDs instead I guess.

11. Watts is a measure of power consumption. A 40 watt lamp uses 40 watts of power. Assuming all of this power is converted to heat, which it is not. A 40 watt lamp would produce about 136 btu's. A 15 watt CFL would produce 51 btu's. The rating on the fixture is determined by testing labs and is the maximum rating that will allow the fixture to run continuously without creating a fire hazard over the life of the fixture. Exceeding those ratings is asking for trouble. You can safely put a CFL that consumes 40 watts of power in a fixture rated for 40 watts, assuming it will fit in the fixture.

12. As stated,it has to do with heat generated, not the size of the wire, at least in normal household lamps. I believe the minimum size wire in lamps is 18 gauge which has the ability to carry up to 14 amps (I was shocked to read that in my code book, no pun intended) depending on temperature rating and insulation type.

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Just thought I'd mention that, besides the heat and wiring, the rating can also be a product of the rating of the switch.

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sockets that are rated for 60 watts are usual made from plastic, higher watts light are ceramic or another heat-proof material

15. Ray, that is interesting info. How does that pertain to my question, though?

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