[PsychMan]

I would personally add some snubbing, if only just a capacitor across the contacts. The transients can be very high on switch off for inductive loads, and as I understand it as the contacts disengage the transient high voltage will be enough for a spark to jump the gap, and over time carbonise (if that's a word!) the contacts. You can see the effect displayed quite nicely on even a piddly little record deck motor (On the Garrard decks which have switch contacts under the platter with transparent covers..)

As always It will be interesting to see what learned forum folk can offer on this topic