In article 3bxRj.99570$rd2.14985@pd7urf3no, Tony Hwang wrote:
wrote:

On Mon, 28 Apr 2008 15:00:45 GMT, Wayne Boatwright
wrote:

On Mon 28 Apr 2008 06:44:08a, told us...

Subject: Dimmable CFL
From:

On Apr 28, 9:23ÿam, Jim Redelfs wrote:

In article ,
(Don Klipstein) wrote:


I give low odds of its energy efficiency exceeding that of a 230 volt
incandescent being powered by 120 volts

Do you believe that 130V-rated (commercial?) incandescent lamps,
operating at ~120VAC, are longer-lasting enough to be worth the hassle
of getting them (wholesaler) and price, compared to an everyday bulb?

Yes, I believe that, and almost all the incandescent bulbs I have in my
home are 130v-rated. Their logevity is astounding.

They use more electricity, however.

Hmmm,
I don't think so. 130V rated lamp is on 120V circuit.
Simple Ohm's law.

A 130V incandescent being operated at 120 volts consumes about 89%,
maybe 88% of rated power. (Not 85% - the filament's resistance varies
directly with temperature.)

And when a 130V incandescent is operated at 120 volts, it produces
about 75-76% of its full light output. Efficiency decreases a lot when
an incandescent is underpowered.

A 130V 100W incandescent only outshines a 75W 120V one due to
incandescents having "economies of scale" that reduce the efficiency of
lower wattage and lower current ones. A 75W 120V incandescent produces
about 69% of the light of a 100W one.

One more note: If you have incandescents on a dimmer and usually
operate them dimmed, consider using a lower wattage to use less dimming.
Although a 75W incandescent produces 69% of the light of a 100 watt one,
a 100 watt one dimmed to consume 75 watts has about 53% of its full
output.

That leads to another consideration: Reduce the number of bulbs if
you can - a smaller number of higher wattage bulbs will be slightly
more efficient than a larger number of lower wattage ones. Just don't
take this to an extreme that affects evenness of illumination.

- Don Klipstein )