"Phil Allison" wrote in message

"Arny Krueger"

** Another brain teaser.

** The control on the commercially made, domestic lamp
dimmer is set to max.
With incandescent lamps it traverses the whole, half
cycle range just fine.
At lower settings, the current draw becomes half wave
with much larger peaks.

Now, can you say what the problem with this is ?

Is this CFL designed to be dimmed?


** In common with almost all of them - no.

This is a mystery to me: I have bought about 100 CFL that are fully
dimmable. Some for as little as $5.

If the CFL is not designed to be dimmed, my personal
experience says that the real question is whether or not
the dimmer or the bulb will be the first to emit smoke
and die. The reason for the failure would be the
extremely high current peaks.

** Arny has supplied the correct answer.

The CFL in my test was a single Philips "Genie" rated at
11 watts.

The PROBLEM is that it APPEARS to a user to work more
or less OK on a common triac dimmer.

However, the RMS current draw when used with one is 3 to
6 times the value normally seen - which will soon over
temp an internal 10 ohm resistor in line with the AC
supply. Smoke and fire is the result.

With several CFLs on the same dimmer circuit - the
combined current peaks will likely destroy the triac in a
few seconds.

Makers supply either NO warning or a completely
inadequate warning of this serious hazard to purchasers.

I checked the CFL on sale in retail stores around me. There was always a
warning on the ceramic part of the base, and either a warning on the
packaging, or the packaging exposed the warning on the bulb.

With the impending ban on incandescent lamps here in
Australia plus Europe and elsewhere - this is gonna
cause a major safety issue.

I agree. Given that dimmer-friendly CFLs exist and are available on the web,
why aren't they endemic in the retail stores?