• Trane XV80 air handlers.
  • These really caused me pain at a previous house putting several volts of noise onto the powerline whenever the fan was running. The noise was such that it would interrupt X10 signals as you would expect, but it also would put many modules into a mode where they would just randomly turn on, or would turn on when the next signal was received regardless of the address of it. Several nights I had to jump out of bed and hit the button on our bedroom overhead lights which had just popped on before it awoke my wife… The solution was to rewire the air handlers in the attic! Instead of a direct connection to their power circuit a regular 15 amp electrical outlet was installed and a heavy duty plug installed on the wires to the air handler. This allowed me to plug the entire air handler into a 15 amp X10 filter solving the problem completely. Since it was only the blower on that circuit it was no problem to do this as we were not dealing with high amperage heat strips or the AC compressor.

• Pretty much every UPS.
  • UPS's almost all have filters in them which shunt X10 signals to the neutral as noise reducing their power or eliminating them completely. If you have any UPS it should be assumed it will need an X10 filter before you can reliably control anything.

• GE Electronic florescent tube ballasts.
  • I recently replaced the old, dim, buzzy, flickery magnetic ballasts in my garage with new shiny electronic ones from GE that I purchased at Home Depot. Unfortunately after doing so I could no longer control the lights nor any other ones on the same circuit. Sure enough they generate a huge amount of X10 noise when running. An inline filter or repurposed X10 light switch filter coil is necessary to get things up and running again.

• Many computer power supplies.
  • This seems to be a lottery. Some people are able to run their computers without difficulty but for others the power supplies either suck X10 signals or generate huge amounts of noise. If you have problems you may need to have your computer plugged into a filter. If you have the computer plugged into a UPS, then you'll need one for sure for that anyway and it will solve both problems.

• Dimmable florescent lamps.
  • I need to get some video of the fascinating effect that dimming some new dimmable fluorescents has here. There are too many brands out there to list individually but if you are adding some of these to your mix be prepared to require a plugin filter or an inline module to keep the rest of your system working. (this turned out to be a problem with the X10 wall switch and NOT with the bulbs! replacing the switch solved the problem, though the lights still were sub standard and have been replaced)

• Cordless tool and other battery chargers.
  • These can be hard to track down as the amount of noise can vary randomly or in connection with the actual act of charging (which can turn on and off if there is a charged battery sitting in one) Plan a filter for any such things.

• Old CF bulbs that worked perfectly for years.
  • The ballasts in these little lamps may work perfectly for years and years and while they may still light the filter capacitors or other things get slowly damaged by heat and by running right at their rated maximum power for so long and some day may start to cause trouble where there was no trouble before. Just because it's been there and harmless for so long doesn't mean it's not a problem now.

• My dishwasher
  • I am the otherwise happy owner of a Maytag “jetclean” dishwasher that generates a large amount of noise when the motor is running. I couldn't get it pulled out from under the counter so I installed a 20 amp inline filter in the electrical panel.

• “surge capacitor” type whole house surge protectors.
  • There are numerous fancy whole house surge protectors that are not based on MOV circuits but on what they call a “surge capacitor” I believe they filter the power based on the high frequency of a surge rather than just clamping the voltage? But they will also happily filter ever single X10 or other powerline signal from your house as well. There are numerous quality MOV based whole house surge protectors that cause no problems, stick with those.

• X10’s own maxi controllers
  • Pretty much any X10 transmitter can also attenuate other signals. I’ve read that before but never really experienced it until recently. The same member of our mailing list who found his surge protector was generating noise also had a large number of maxi-controllers which he discovered were eating his signal strength severely. (hello George!) If you have an unusually large number of these you may want to look to that as a source of low signal strength.

any of these things may cause trouble for other powerline protocols as well. Different things may cause problems for insteon or UPB but similar things will and do cause problems for them too.