x 10 switch

[zotdoc]

Is there anyone who can explain why an x-10 switch will not work with flourescent bulbs?

[Engineer3104]

There are a few reasons why an X10 dimmer will not work properly with fluorescents. I am assuming you're talking about the simple 2 wire dimmers like the WS467 or PLW01. These dimmers are wired in series with your load. A small amount of trickle current must flow in the circuit to keep the circuitry in the dimmer alive. This small current also flows through the load. There has to be enough current, so the specs say you need a minimum load of 60W. That's when the dimmer is off. When it turns on, it effectively shorts itself out. If it was a complete short, there would be no voltage across the dimmer, so it's circuitry wouldn't be powered up. To fix that problem, the dimmer steals power from the lighting circuit. It actually doesn't turn for about the first 8 to 10 degrees of the sine wave. During this time, it charges up a capacitor to provide power for the circuitry for the rest of the half cycle. So even when the dimmer is set for full brightness, it's not allowing a complete sine wave to appear across the load. Incandescent light bulbs don't really care, but the inductive ballast in a fluorescent fixture doesn't like to see non-sinusoidal waveforms, with abrupt edges.
Also, in order for an X10 signal to control the dimmer, it needs to pass through the entire circuit, from line in, through the dimmer, through the load, and back on the neutral connection. Fluorescent fixtures present a high impedance to the 120kHz X10 signals. In a lot of cases, the signal is not strong enough to be seen by the receiving circuitry in the dimmer.
Also, remember that 8 to 10 degrees at the beginning of the sine wave? That's where the X10 signal is transmitted. So the dimmer isn't doing anything at this time except looking at the sine wave to see if there's an X10 signal superimposed on it.

Does that help clear things up, or did I just make it worse?

[Bigglez]

Incandescent light bulbs don't really care, but the inductive ballast in a fluorescent fixture doesn't like to see non-sinusoidal waveforms, with abrupt edges.

That waveform is still a sine (rich in odd harmonics) with Triac control.
Fixtures with low voltage incadescents and transformer drive
can operate on a dimming control (or probably an X-10 switch).
Some CFLs and fluorescent lights also work on dimmers with
symmetrical AC Triac drive. This is not the case for SCR drive.

A HF blocking load can probably be modified to pass the
X-10 120KHz data signal, with a capacitor shunt.

Another trick is to have a mix of incadescent and non-incadescents
on the same load.

[dacflyer]

if you want to use a CFL or other gas discharge lamp, go with the plpug in appliance modual, it uses a relay to turn lights/ appliances on and off, i use them a lot, works just fine.
the lamp moduals use triacs, not relays.
i use about 6 appliance moduals on several kinds of things. motors, fans , yard lights, cfl lamps, it all works fine.