Varistor or Cap on Power Switch?

[RockinRocket]

What did Ken put on the power switch?

I've all ways thought it was a cap to snub popping when switching off.
William Vogal said he put a Varistor on one of his builds he posted here. That got me thinking.

What was it and I don't understand what a varistor does on the switch?

[wpaulvogel]

It’s to protect the amp from being hooked to excessive voltage supply. The varistors are rated for 135 or 140 volts I think. If you plug the amp into more than the rating it shorts to neutral the excess voltage probably popping the house breaker.

[RockinRocket]

Thanks , I ordered the ones you used last night.

[Aurora]

Varistors are for over voltage protection... usually from spikes on the network. While it will short to ground if you connect to a too high input voltage, it will also most certainly burn the varistor.... if the circuit breaker pops before something else..... anyones guess is as good as mine...