220VAC 20amp gang breaker; really 40 amps?

Double pole breakers are rated with a a single value. If your device is

220V comes through one leg of the breaker and returns along the other one. Multiple circuit breakers don't add their capacities, it's more like the "weakest link". If a breaker in the series was 10A it would trip every time your 15A load started.

Mike O'Donnell

As an add on to my previous post:

I suppose you could use two adjacent breakers, with their handles physically tied together (I don't know if that's acceptable under code, and it's probably not a good idea anyway even if it is legal).

In that case you would still need 20A breakers since they're in series..

Mike O. (no I'm not talking to myself.. At least not at the moment..)

Thanks for the help folks. I got the compressor wired up with #12 which runs about 20ft to the breaker. And yes, I have a 20amp double pole.

Thanks!