I don't know why one would look to a snubber to protect a switch. Snubbers, RC, RLC, are typically employed to control dv/dt on semiconductors. I don't consider a capacitor alone as a snubber. It is pure reactance and therefore non dissipating. A snubber needs resistance to dissipate energy.
A switch should be able to sustain far more transient voltages than semiconductors. Switches in old equipment can be worn out in several ways. Spring fatigue, contact erosion or oxidation, lubricant contamination, time, all contribute to ware out.
Switch failure on closing a normal load, even a cap input load, would seem to indicate a warn out contact. This could be worn springs that allow excessive bounce an arcing.
Switch failure on opening a load can be a different issue. If the switch is overloaded, arcing will eventually erode the contacts and lead to some kind of failure or weakening of springs.
For normal switches in "typical" electronics, a 1000-10000pf cap across the switch should suppress most contact arcing. (~300-3000K). I'm sure I'll get some flaming on this, but mechanical components work different than semiconductors.
Kevin
