Strange UPB dimmer issue

[rsw686]

I have 8 HAI UPB dimmers that have been working great since their install a year ago. Recently I've been having issues with one of the dimmers that has 4 CFL pot lights attached. When the dimmer is off I can test / get status / program it from UPStart Once I turn it on UPStart fails to see the dimmer and it won't respond to commands. The dimmer will respond to a link sent from another dimmer in the same room. A UPStart device to device comm test shows excessive noise only when the dimmer is turned on.
 
My first thought was noise from one of the CFL bulbs. I tested removing a bulb and the dimmer will respond to UPStart when turned on. The kicker is I can remove any one of the bulbs. With any 3 bulbs connected UPStart will show no noise and the dimmer works correctly. I went as far as to swap out each bulb one at a time with a spare CFL bulb. As soon as there are 4 bulbs connected the switch fails to respond.
 
Any thoughts? I'm assuming the switch is bad at this point, but it doesn't make sense that it works with any 3 of the bulbs.

 

[Desert_AIP]

The bulbs have probably worn the cathodes enough to produce noise when they are all on together.
It's below the threshold with only three bulbs.
It will likely get progressively worse.

I'd replace the bulbs with LEDs.

The switch is probably OK.

 

[rsw686]

It was the bulbs. I replaced them with Cree BR30 LED bulbs and the switch is working. The switch in question was on the opposite phase as the PIM so the signal was low to begin with. I only got 3 years of life out of the CFLs. I have another switch on the same phase as the PIM with CFLs that are around the same age. With the light on I'm seeing a noise level of 2, but the signal is 55 vs 10. It looks like I will get another year or so out of these.

 

[Desert_AIP]

Even CFL tech has come a long way in the past few years.
But LEDs are a better technology, you'll like those Cree bulbs.

 

[RAL]

LED bulbs can create power line noise, too.   A friend purchased half a dozen cheap, no-name LED bulbs on eBay and when he installed one, it wiped out all his X10 automation.  A check with a signal strength meter showed the noise was off the scale.   Every LED bulb from his purchase caused the same problem.  It taught me to stay away from the no-name stuff.

 

[rsw686]

Even CFL tech has come a long way in the past few years.
But LEDs are a better technology, you'll like those Cree bulbs.

Yeah I'm a fan of the Cree bulbs. I have a few of their A19 bulbs, which is why I went with their BR30 bulb. I like the LED filament tower design as it produces light that resembles an incandescent bulb. The first LED BR30 bulbs I bought a year ago where from Philips. They are nice, but even with the diffuser the light is harsh if you look up towards the ceiling.