Need some help, woried about using cheap 49.00 microwave in camper( motorhome) does anyone know does it need to be comm because of mag tube?

 

Sorry ,but what are you on about, are you from planet Earth?

 

Your only concern, really, is your power source : if inverter, cleanliness of output frequency - how close to sine wave vs. square wave, or adequate wattage of your generator to handle multiple loads.
as long as safety switches on the door are intact and not jumpered or otherwise tampered you shouldn't have any issues.

 

If your only issue is you have power company power but no ground lug then your equipment should be safe to use, but you've eliminated an inportaint piece of safety equipment for YOUR safety.