When does a 15 amp dble. Pole breaker apply other then 220 volts?

When it is installed in a panel that delivers voltage other than 220 volts.

Please explain your situation and the reason for the question.

If it is a DPDT breaker it can be used for two different purposes.

1) Deliver 240 volts to equipment.
2) As protection for a multi-wire circuit (two 120 volt circuits with a shared Neutral)

A DPDT?

You mean a DPST.

You are once again correct. I must have a loose nut on my keyboard!

I swear you can find anything on the net.

Breakers are never referred to as DPST, DPDT, etc.

I do not think there is a Double Throw breaker made.