Note: As far as I know fluorescent bulbs should only be used with X10 appliance modules. I recommend educating yourself before using them in any module. Also, it’s important to be aware that the use of fluorescent bulbs can cause powerline interference. According to what I have read the use of fluorescent bulbs in other modules, especially dimmer switches, is a fire hazard (unless the bulb is specifically made for dimming).
Before I started using X10 automation modules I had replaced all of my incandescent bulbs with fluorescent bulbs. When I started adding X10 I learned that fluorescent bulbs can only be used safely with appliance modules. If you want to know more there are plenty of resources that can be found with a simple search.
I recently switched from incandescent bulbs receiving power from lamp modules (dimmer) to fluorescent bulbs powered via appliance modules with three lamps. Everything seemed to be working fine.
However, my wife noticed the guest room lamp bulb flickered faintly when off. I inspected the module and realized that of the three in place two of them were from X10 but one was an RCA module. This issue wasn’t present with the X10 modules. I removed the RCA module and swapped it with an X10 module from a box fan and the problem did not occur any more with the lamp.
My guess is that the RCA module “leaked” a small amount of power (probably to allow X10 signals to pass through). I had read about this issue previously so I wasn’t surprised. This can also be a factor with certain fluorescent bulbs.
Now, some of you may be wondering if you can use a fluorescent bulb that is made to dim. The answer, as far as I know, is yes. In fact, I’m using one with a lamp module. It’s capable of dimming (and not being a fire hazard) but I do notice a faint flickering and it doesn’t dim as far (or as smoothly) as an incandescent bulb. This is another topic I suggest you do more reading before implementing. Users have reported different results with different bulbs (some are now available that can dim further, operating on lower power levels).