Quoted from: http://www.jkmicro.com/documentation/pdf/inductive_loads.pdfB) If you are using a relay to switch an AC-powered inductive load, put a
varistor in parallel with the load. The varistor voltage rating should be about
1.5 times the peak-to-peak steady-state voltage of the load.
C) Relays switching an inductive load may require a capacitor placed across
their contacts. 0.1ufd to 1.0ufd is a good starting point. If the relays are
switching an AC load, place a 100 ohm resistor in series with the capacitor.