Hi all first time post, not sure if this is more an electrical wiring question, but it relates to HVAC so here it goes. I live in Minnesota with very detailed requirements for makeup air for range hoods. I am installing a whirlpool WML750MZ OTR microwave, vented outside, rated at 400 CFM. Range is a Samsung 30" gas 5 burner. I preinstalled the unit this summer while waiting for the cabinets to arrive, and it seemed to work OK, other than being loud, and since it was summer the windows were open most of the time, so I didn't notice any problems with backdrafting or anything. as I got closer the remodel I started digging into into the codes (after bing told I didn't need any MUA), and found out I am right on the edge of needing powered makeup air. Home is a 3000 SF 70"s split level, with new windows and a fireplace, atm vent WH, gas dryer, and when I did the MUA calculation, I was maybe 180-200 CFM short, based on house age and SF, and appliance load. So I thought, OK, I'll get one of those Braun dampers to let air in, and found I needed a 10" duct, and then heating the makeup air was essentially a requirement before introducing it into our furnace for distribution to the kitchen. So then I though, might as well get one of these MUA package units with a blower and heater, and just be done with it. My amateur calculations show the Electro Industries 350 CFM/5KW unit should work pretty well for my needs. Finally getting around to my question- This will require a 240V 30A power supply. the unit runs right next to the AC power line, also a 240V 30A supply. Would it be a terrible idea to run the MUA unit off the AC circuit? The MUA unit has a temperature cut off for the heaters of 50C, so the 2 units should (in principle) never be running at the same time. I do have a 60A subpanel feeding kitchen outlet circuits (2X20A), range (15A), MW (20A) and some LED lighting, so this probably has the capacity, but I thought the AC circuit was an interesting idea, and interested in any thoughts on the idea. Thanks for reading this far!

Eric

PS- I wish I would have found the Range Hood FAQ II prior to starting my project! The OTR microwave might not be installed forever after reading about proper hood design.