In article , Robert Neville wrote:
Nate Nagel wrote:

Well... I don't know whether a 15W CFL produces more or less heat than a
15W incandescent. I ASSume less, but I don't know how much less. That
said, the largest CFL I've seen is 23W and we're talking about 60W light
fixtures, so I don't know that it matters all that much.

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.

I consider at least some of this optimistic.

A "standard" 100W 120V A19 incandescent rated to last 750 hours and made
by one of the "Big 3" (GE, Sylvania or Philips) and with "CC-8" style
filament is usually rated to produce 1710 lumens, sometimes 1730 or 1750.

CFLs getting that high tend to have wattage at least 26 watts, though I
am aware of a non-spiral one by Philips rated to achieve that with 25
watts.

With a couple thousand hours of aging and/or even only moderately
non-optimum temperature, 30 watt spirals hardly get past 1750 lumens.

At least a 30 watt spiral will not overheat a fixture rated for 60 watt
incandescents - but it can easily overheat itself in small enclosed
fixtures and downlights.
Safer is 23 watts - "a bit dimmish for 100 watt incandescent
equivalence" is what I would call those. After a few thousand hours of
aging and/or off-optimum temperature, I would like to call those
equivalent to 75 watt "standard" 120V incandescents (which traditionally
produce 1190, sometimes 1210 lumens IIRC). 23 watt CFLs nowadays are
indeed rated to produce 1600 lumens right after they have gotten past the
first 100 operating hours.

Also, I tend to see a CFL of usual 2700K color temp. rating a few
percent dimmer than an incandescent of same lumens due to the
scotopic/photopic issue, which I find a bit significant in most home
lighting. I would not counter that with color temps. above 3500 K - color
temp. above 3500 K easily appears "dreary gray" in most home lighting.

What I like to do is consider 13-15 watt CFLs to be comparable to
"longlife" and "industrial service" 60 watt incandescents, 18-20 watt CFLs
to be comparable to 1,000 hour 60 watt incandescents, and 23 watt CFLs to
be comparable to 75 watt 750 hour incandescents.

- Don Klipstein )