20 amp breaker on 30 amp wire

[Part-Time]

Can you put a 20 amp double pole breaker on
A 30 amp (#10) wire or would the breaker have to be sized to
Wire and use a 30 amp DP breaker. The load on the window AC
is 16 amp max it heats and cools. Any code reference that would help?

 

[augie47]

I'd start with 440.62, then 210.21(B)

 

[Dennis Alwon]

The breaker is the protection for the wire, generally speaking. Many times we increase the wire size for VD but the breaker still must be sized to the circuit it protects.

 

[ActionDave]

You can always use larger wire on a smaller breaker. The code only requires that the conductors be protected at not less than their listed ampacity.

 

[kwired]

Can you put a 20 amp double pole breaker on
A 30 amp (#10) wire or would the breaker have to be sized to
Wire and use a 30 amp DP breaker. The load on the window AC
is 16 amp max it heats and cools. Any code reference that would help?

Put 500 KCMIL onthe 20 amp breaker if you want. You will need some kind of adapter to make it fit however.