I am working on a circuit board design that uses a fuse resistor for protecting from short circuits and a varistor to protect from over voltage. The board is a simple power supply of only a few watts.
If I have a 275V varistor, what should I be looking for as the maximum voltage handling of the components protected by the varistor? I am not looking to use components with less than 275V handling, but want to know if I would need a 300V , 325V, etc. capable part behind the MOV for example. I have not been able to get a good feeling for the allowances that are required.