Dan Miller :

Is it possible to wire a 3 phase switch for two phase power?

Peter H. wrote:

Yes, but one lead of the two-phase line will not be switched, and that is
now a no-no.

Can you elaborate on this?

I assumed the OP meant single phase 240V (L1 & L2).

In my case, I switched a single phase, 240V motor with a 3-pole switch.
My understanding was that the switch could be used for a 3-phase device
because all 3-poles open or close simultaneously. I simply connected each
hot to a pole and then provided a proper equipment ground. The middle pole
(switched contacts) was not connected to anything.

This wouldn't strike me as being a code violation, but I have not looked
at the most recent NEC.

Did you mean one line always hot and the other switched for a 240V load?

Jeff Dantzler