Ground Loop?

Since you mentioned two dedicated circuits, are you using isolated ground receptacles? If so, check the ground wires. Remember, an isolated ground requires an insulated ground wire. You should not use Romex. The ground wire is not insulated. I’m not an electrician but when I installed a new receptacle for my system. Based on my readings, an isolated ground has different grounding specs. In my case, I could not use an audio grade receptacle like PS Audio or any other brand that required an insulated ground wire for an isolated ground. I ended up using a Hubbell 8300 hospital grade receptacle. Hope this helps.

Do your wattgate receptacles have an isolated ground? If so, check the specs. Call their tech support. Most, if not all, isolated ground receptacles will require an insulated ground wire. If this is the case and you are using standard Romex, your ground is compromised. 

Cleeds is correct. At 20 awg, you aren’t even close to a 20 amp code requirement. For a 20 amp circuit, you should have at a minimum, 12 awg wire. Personally, if this was a custom job, I would run 10 awg stranded wire in metal flex conduit. Again, I’m not a certified electrician but you may have much bigger problems than the ground. How long is the run of AQ 20 awg wire? Is the AQ wire rated for 20 amps at the length of your run? For your sake, I hope the electrician verified all the specs before installing the two circuits. Worse case scenario, one or more wires will heat up and possibly cause a short or fire.

I’m so glad! When I read 20 awg, my heart sank. If you used audio receptacles, check the ground requirements. If interconnects are running to a device on a different ground, this may be the source of the ground loop. Hope you figure things out. Have a great weekend!