On Tuesday, May 17, 2016 at 9:15:25 PM UTC-5, wrote:
On Tue, 17 May 2016 18:57:47 -0700 (PDT), bob_villain
wrote:

I want to put a sub-panel in a connected garage. Can I use 6-ga. 3-wire to supply a panel with 4 breakers (20A each)? Do you have to consider the possible use of all of the circuits carrying the maximum load? Thanks!
You can if you put it on a 40 amp breaker --- You DO need a feed
breaker for the panel.

So you're saying a 40A feed breaker and the sub panel can have 2 20A breakers?