I would have to see the codes, captured with a storage oscilloscope or logic analyzer before I believe it's the three CFL'S noise magically combining into a P1 followed by POn. Occam's Razor would seem to support the hypothesis that whatever mechanism causes modules to turn on or off in response to spikes or sags is at work here.
Remember that two of the Cincinnati area users who saw random events related to smartmeters found that Smarthome made modules set to the same address were immune - that would seem to deflate the random codes from noise hypothesis.
Dave, you've been talking about spikes for a long time. While that may cause some of the problems, I don't believe that is the cause of problems for either my office/lab or the Echelon smart meters that have been installed in the Cincinnati area.
I have watched the beat pattern from those CFLs create random decoded strings of 1’s and 0’s. In years of testing, that P1 appliance module has never turned on unexpectedly during the day. It has turned on several times at night while the CFLs were switched on. We have a whole house surge protector, and I have never seen any significant spikes on our powerline.
The fellow who helped develop the Smart Meter Rejection kit used a Tektronix spectrum analyzer to understand exactly what the Echelon Smart meter was doing. It produced very strong signals at two frequencies near the X10 passband. His X10 modules were switching at random when those signals were being transmitted. We added filters to block those transmissions, and the random actuations were eliminated.
The SmartHome devices use a different input stage compared with the X10 products. They may have narrower bandwidth or AGC to ignore the continuous powerline noise.
The theory of P1 being the last “arming” command might be valid in the case of that appliance module. Since I use the P housecode for testing, it is certainly possible that a P housecode was the last command sent on that circuit. It is isolated from the normal automation circuits, so those commands may not override the last P command sent. (The noisy CFLs are controlled by an ordinary wall switch.)
Jeff