In article ,
Alan Black wrote:
Sorry, I did think that he meant single phase.

That is a reasonable assumption, given the relative rarity of
real two-phase power form the company, and the fairly common mistaken
assumption that the 220V is two phase.

If 4 wire two phase is two
hots 90 degrees apart and two companion neutrals , I'm not sure if you need
to switch the neutrals too. Of course with three phase you must switch all
three.
Alan

And another question is what kind of load is planned? Assuming
that he really *did* mean 220V single phase to something like a
reversible lathe motor, then he will need all three sets of contacts (on
a typical drum switch) to be able to start the motor in either
direction.

For a single direction of operation from 220V single phase
(neutral center tap), you can get away with only two contacts.

Enjoy,
DoN.
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