[Richard]

Thanks for getting back with the solution.

I am going to do some public pondering here because the root cause may apply to others during this very chilly week.

There are a couple of things that might have happened. If the heaters are plugged into an inverter circuit, the added load of the micro could have overloaded the amperage rating of the internal transfer switch in the inverter, causing a fault. Or, given the demand on the grid, the voltage could have dropped causing the power protection device, if Adrian is using one, to temporarily drop out on low voltage. The inverter would have immediately kicked in when the power protection dropped out, causing an overload on the inverter. These are just out loud musings about what might have happened.

My point to the forum, is it might not be the best setup to plug supplemental heat into inverter based circuits.