Will a bigger inverter avoid the dreaded alarm?

mkirsch, that is the solution we have adopted -- it is ok to run the furnace while DW showers (mandatory in very cold weather!), but then we can't charge the phone at the same time. No big deal -- we wait to charge the phone. But I was trying to figure out whether a bigger inverter would solve the problem, and the answer is no -- this is about inadequate wiring. That is useful information!