Hey,
This mains interference you mentioned, like a voltage spike (sudden change from 0V to ±110V/220V) could damage the appliance in the long run?
For example, if the load is inductive, and the voltage starts off with -220V, then since the current should follow the voltage (and not backwards), the current would fall down quickly from zero to a very negative value (with amplitude larger than its steady-state amplitude).
Dont such cases damage the appliance? (at least in the long run).