AC or DC coils?

[DrStrangelove]

I've seen various circuits for relay drivers (DC) that hit the coil with a higher voltage to pull it in, then reduce it to the much lower voltage needed to hold the relay in.

As for the contacts, as mentioned by Sam, breaking DC (by relay or switch) at anything above very low voltages can give some impressive arcs if it isn't done correctly.  The DC isolator for my PV panels is actually 3 or 4 standard AC isolator sections wired in series. It has to break up to 500V or so.

I seem to remember somewhat vaguely that some tape recorder pinch roller solenoids used the full voltage to pull the thing in, then a reduced voltage to keep it there.

I may, of course, have dreamed that.