Drop in electric power (110 volt)

That's a good idea, but you will need to be sure that you maintain the coupling to the AC mains earth ground for the Legacy signal.

Great. Thanks for that info.

You need to increase the gauge of the feeds to the A-C units, and to the layout power source. A drop of more than ~ 3 volts per 120 volt leg is unacceptable.

Have you recently checked that the starting capacitors in your A/C units are working properly? A bad cap can certainly cause an instantaneous AC voltage reduction to the whole house....or can you set both A/C units so they don't turn on at the same instant? 

You might look for real sine wave UPS units for your backup power, I don't know how the Z-4000 transformer will react to the typical power that comes from some UPS units.

Thanks guys for all the responses. I will pass all this on to our electrician & relay all your thoughts. This is well over my knowledge.

Stay safe & healthy.

Speaking as a HVAC tech if when the compressors start the voltage drop from the inrush current is effecting your 120VAC supply that much I think you need something looked at. That being said I do A LOT of work in rural Kansas so I also know sometimes it’s the electrical grid ( or lack there of) and there’s not much that can be done. But I would simply check basics. Make sure the Compressor run capacitor is with in specs and check the amp draw when starting and running and compare it to the rating plate. My go to “fix” (not guaranteed ) is a hard start kit that typically helps the compressor start and keep the inrush current down. That being said if there are other issues like mentioned above with the high voltage line being too small to handle the current or something to that effect most anything is just a bandaid

@zhubl posted:

My go to “fix” (not guaranteed ) is a hard start kit that typically helps the compressor start and keep the inrush current down.

Excellent suggestion!  I forgot that, years ago, I had to add the hard-start kit to the A/C compressor after installing the 18 KW Genrac backup. It solved a lot of problems.

Zhubl & Bruce, thanks for those responses. I will plan on having our HVC guys checkout our AC units when the system is serviced in the spring.

John there is one thing you can do besides what I had told you to help your power be a normal constant voltage at 120 VAC . contact your electric utility I know because i had to do this if your house is tied in with 3 or 4 houses your incoming power can be lower, so if you contact your power company and ask them to install a transformer on your pole next to your how you power won't be so low ! ask me how I know this I've been threw the exact same issue your having with 110 or even less voltage different times of the day, If you complain you can have them hook up a meter for monitoring your voltage for a week or so they will fix your problem by installing a transformer for your house !

Alan Mancus