2-Pole vs 3-Pole Breaker

[philly]

We have a 1-Phase 480V circuit that we need to supply a 70A breaker for. Should I supply a 2 pole or 3 pole breaker for this feeder circuit?

I know it should be a two pole breaker due to the single phase nature of the circuit, but in the event that sometime in the future this circuit was converted to a 3-phase service would it be a good idea to have a 3-pole breaker avaliable?

Or is putting a 3-pole breaker on a single phase service a code violation or not good practice?

 

[Volta]

What do you mean by "service"? Branch circuit? Ok if so, but may be wasteful.

But if you actually mean service when you say service, then 408.36(C) won't allow a 3-phase device to be installed in a single phase panel.

 

[philly]

What do you mean by "service"? Branch circuit? Ok if so, but may be wasteful.

But if you actually mean service when you say service, then 408.36(C) won't allow a 3-phase device to be installed in a single phase panel.

This is actually a feeder branch circuit which will be feeding a 25kVA transformer.

I take it that a 3 pole breaker costs more than a 2-pole

 

[LarryFine]

Phil, if you're correct that a 3p breaker will eventually be installed, it could be better to install the 3p breaker now.

I guess the one ultimately paying the bill should be informed of the options and costs, and be allowed to decide.