CFLs vs incandescent "max wattage" cautions in overhead fixtures....

[CJT]

I don't think he said anything like that. Your hypothetical 7500 watt equivalent CFL would draw more than 100 watts, so fall outside the design parameters.

[Bob F]

Closed fixtures - those without good airflow around the bulb, can cause overheating, and resulting shortened life.

[tnom]

My point is that a light fixture rated for a 100 watt incandescent only has to be robust enough to support the current of that same bulb.

1 amp.

[AZ Nomad]

As long as you don't exceed the current and heat ratings, you'll be fine.

[AZ Nomad]

No. Where'd you get that insane idea?

[AZ Nomad]

If it somehow drew 100W (less than an amp), you'd be fine.

What part in "put out the light of a bulb" don't you understand? I didn't say "consumed the current of a CFL.

[tnom]

So now you are bringing current into the equation. I'm glad the light bulb turned on.

[Nate Nagel]

Did you read the words that I typed?

I'm guessing... no.

nate

[Nate Nagel]

yes, we've covered that already.

Can you find an example of a CFL that draws more than 100 watts? What point are you trying to make, anyway?

nate

[Robert Neville]

There's basic physics at work here. Watts are a measure of electricity consumption, not light output. Heat produced is completely based on watts consumed. Incandescent bulbs are essentially electric heaters that happen to throw out a small amount of light. You just need to make sure you are comparing the actual current draw and not the equivilent light output.

A modern "60w" CFL is using less that 15w of electricity, the "75w" draw about

18w, and "100w" use about 23w actual.

[AZ Nomad]

I never proposed exceeding a fixture's current rating.

[Robert Neville]

Thats a nonsensical question. If you are drawing 20A of 120v AC electricity, you are using 2400w of electricity*. And there will always be heat involved.

*Assuming the power factor is 1, which for light bulbs and most residential useage, is true.

[tnom]

My point has always been about the fixture and that it has current limitations that haven't been clearly pointed out.

[Don Klipstein]

I have one data point of experimentation indicating that a 42 watt CFL produces slightly more non-radiant heat than a 60 watt incandescent. Therefore, it appears to me that CFLs of wattage much lower than 42 watts will not overheat fixtures rated for 60 watt incandescents. This means that CFLs of wattage up to low 30's should be OK, and those tend to outshine 100 watt incandescents.

Meanwhile, CFLs can overheat in some fixtures. My experience is that ones over 23 watts have a significant rate of overheating in downlights.

23 watt CFLs tend to be "lowish 100 watt" incandescent equivalence, usually outshining 75 watt incandescents.

You may ask - how could a CFL be more efficient than an incandescent at producing both light and non-radiant heat? The answer is that the CFL produces much less infrared than an incandescent does, especially much less in the 700-2500 nm range.

- Don Klipstein ( [e-mail])

[tnom]

But you and others originally omitted any mention of current, and focused only on heat instead.

[Don Klipstein]

I hope you mean "75 watt incandescent equivalent" - which is usually

18-20 watts.

- Don Klipstein ( [e-mail])

[Nate Nagel]

I have never seen a fixture rated for less than 23W, making your point irrelevant.

nate

[AZ Nomad]

Will this be the 5 minutes argument or the full half hour?

[AZ Nomad]

time to killfile the clown. tnom isn't interested in any answers, but only in participating in a perpetual argument.

[tnom]

So in all instances 2400 watts of electricity will create 2400 watts of heat? Couldn't 2400 watts of electricity only create 100 watts of heat?