Say you've got an old circa 1954 ceiling light fixture. Spec'd for 2
max 40 watt incandescent bulbs.
My Sylvania 100w-output CFL's take 23w input.
100% safe to use 2 of these CFLs instead of 2 40w incandescents??
On Nov 20, 11:25 am, email@example.com wrote:
I would..........CFL's generate a lot less heat than incandescents.
Those original ratings were based on heat generation & dissipation.
I have several 1930's fixtures that we rated for 60 watt max, that
I've been running 100 watt CFL's in for about a year....no problem.
As an examples a 60w incandescent is too hot to unscrew & handle when
on.....a 100 watt CFL can easily be handle "hot".
Yes. From a safety standpoint you go by input power i.e. the CFLs 23W,
not the "equivalence" power i.e. 100W replacement. This still leaves a
larger safety margin anyway since the rating are mostly based on heat
output and with CFLs greater efficiency it's 23W produce more light and
less heat than a 23W incandescent would. Something like the 42W or so
CFLs, 150W equivalent would be fine as well and damned bright compared
to two 40W incandescence. The "W" is capitalized BTW, Mr. Watt thanks
On Thu, 20 Nov 2008 13:25:05 -0600, firstname.lastname@example.org wrote:
The CFL's will be fine so long as the fitting is adequately
The electronics in the base of a CFL doesn't like heat and can cook up
quite easily if the heat can't get away as in an unventilated fitting.
However, I have had no trouble in any of the light fittings I have put
CFL's into. Most were quite adequately ventilated anyway.
I have installed CFLs in enclosed ceiling fixtures where ventilation might
be questionable. This was well over two years ago and have had no
problems. The wattage, of course, was well under the total wattage rated
for the fixtures.
(correct the spelling of "geemail" to reply)
CFLs are more efficient at producing non-radiant heat than
incandescents. I have found a 42 watt CFL to heat a fixture up very
slightly more than a 60 watt incandescent did.
Incandescents produce a lot of IR, which becomes heat but the IR mostly
escapes the fixture before becoming heat.
- Don Klipstein ( email@example.com)
I wouldn't think any trouble. The old incandescents put out a lot more heat
than the CF. Heat dissipation was the major concern, as I understand it. Use
the 23 watters, and don't give it a second though. Well, if the 23 watters
will fit. Many bulbs won't fit in the older incandescent devices.
There are two concerns with light bulb fixture ratings:
1. The current draw. If the wiring is rated for 80 watts (two 40 watts),
you could potentially overload the wiring with larger bulbs (though
unlikely unless the wires are very tiny).
2. Heat Output. A larger incandescent bulb will put out more heat, which
can degrade the insulation on the fixture wiring. Especially with older
fixtures where the insulation isn't rated for higher temps. I've seen many
ceiling fixtures where the bulbs had heated up the insulation enough for it
to crumble away, exposing the bare wires.
In the case of the CFL's, you would be drawing LESS current (23 watt vs 40
watt), and CFL's put out much less heat than incandescents. So you won't
harm the fixture or wiring in any way by using the larger CFL bulbs.
However, if the fixture is enclosed, you "may" have problems with the CFL's
themselves. Some CFL's aren't designed for even the minimal heat build up
in an enclosed fixture and will burn out quickly. When you shop for the
CFL, try to find ones that are specifically rated for enclosed fixtures
(though many don't specify either way).
I have several 75 watt CFL's installed in enclosed ceiling fixtures around
the house originally rated for 60 watt incandescents. They've been running
for years now with no problems. A huge plus with our high ceilings that
require ladders to reach the fixtures.
Actually, CFLs are more efficient at producing non-radiant heat than
incandescents, despite being more efficient at producing visible light.
What CFLs produce less iof is infrared.
I did actually heat a fixture very slightly more with a 42 watt CFL than
with a 60 watt incandescent. I have a non-contact thermometer.
I would expect the maximum common CFL wattage to not produce more
fixture heating than a 40 watt incandescent to be 26 watts.
- Don Klipstein ( firstname.lastname@example.org)
On Nov 20, 2:25 pm, email@example.com wrote:
Let's see... 40 + 40 = 80
and... 23 + 23 = 46
Okay... 46 < 80
No problem, and you'll have a lot more light in the area to boot.
I replace all my 100W incandescents with 40W CFLs, which are "150W
equivalent" to incandescent. The rooms are way brighter, with a nice
white light instead of a sickly yellow, and I'm still using less than
half the energy that I was before.
Put three 23W CFLs in the overhead fixture in the kitchen. It's like
full sunlight in there now.
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