Wire.. Oh why so many types....

[JAZZCNC]

A contactor is a switch that is controlled by an electric current, not by pressing it. Rather like a relay.

Can also produce quite a bit of electrical noise and large power drain so I'd avoid real contactors and just use normal switch's controlling lower power relays.

[Jonathan]

Can also produce quite a bit of electrical noise and large power drain so I'd avoid real contactors and just use normal switch's controlling lower power relays.

The emi emissions will mainly emanate from the spark when it switches, so if concerned about that I would use solid state relays (or some other solid state device, such as a transistor or triac if appropriate) since then there is no arc.