I'm not an electrician, so this may be a stupid question.
But you're allocating 120 amps to mining in your house. Most homes have 200 amp service and panel. I'm no math wiz either, but that's 80 amps for your home? If you have a heat pump, electric range, and dryer. Aren't you stretching your electrical budget for the rest of the home?
Are you pulling in new service from the street?
Not a stupid question at all. I do have 200 amp service in the home. I looked at pulling additional service, but electrical code in my area says you can only have 1 entry point into the premise. I could upgrade my panel from 200 to 400 though. It will be a while before I go to that length.
I may be wrong in this, but Ive calculated each Antminer S9 pulls a little under 6.5 amps per miner at 220v, which equates to 39 amps for 6. The 6 GPU rigs will pull even less than that, so even with the fans, switch, and other misc equipment, Ill only be using 80-90 amps max.