kwilcox, all: again, thank you. I will pass all of this wisdom onto the installer.
I did receive a few e-mails from Simply Automated today. I'll share what we learned (even before we get back to the home); hopefully, this will help in UPB installations:
1. Installers/electricians must make sure that loads are balanced between the phases to cancel current in the neutral wires.
2. When there is no neutral in a switchbox, a few things can be done:
a. A fixture module can be installed which communicates with the switch, and the fixture module can pass the neutral back to the switch.
b. Although it's not recommended, neutral wires can/may be able to be wired to ground since that's where the power goes anyway.
Also, apparently high-end audio equipment should be on a dedicated circuit with dedicated grounds going back to the panel/mains (vs. sharing a ground with the rest of the home). Apparently, electricians take care of this in new installs, but it can become problematic in retrofits.
Here are 3 URLs which discuss grounding issues for audio systems; I haven't checked them out yet, but they were recommended by the manufacturer:
http://www.audioholics.com/techtips/setup/...loopcableTV.php
http://www.allenavionics.com/VHumElim/SGL.htm
http://www.epanorama.net/documents/groundloop/
I'm thinking we might have SA go out with the electricians and the installer before the rest of us can make it back to the home--and see if we can get a diagnosis before then. I'm hoping that the feedback from this experience helps make all smart home products out there "auto-deal" with a lot of these issues.
If anyone thinks of anything else that can be going on, or notices anything in the text at those URLs that might pertain, please let me know. I'm trying to relay all of this to the installer to see if we can make this work.
Thanks!
Chris