A subpanel does not need its own "main" breaker. You can put one in if you want, but it's not necessary. Counting the load on my fingers (5000 btu on a fairly modern window unit is 500W or so), looks like 50A will be sufficient.

6g wire is fine if it's copper or even 75 or 90C insulation aluminum.

Make sure that your subpanel has the provision for separate ground and neutral bars. Some panels, it's just the matter of removing a strap to separate the two bars, others like square D, you have to buy an additional grounding bar.

Thanks, I've passed my cover inspection! Only thing I have to change for the final is to turn it around so it faces a larger room. Seems my little 5x6 storage room is too small to put a sub panel in.

The size of the room is immaterial but certain rooms might be considered inappropriate for panels and there may not be sufficient working room in front of the panel in a small space.

I'm glad things worked out with your inspector. That's the key.

Unless the panel is on the wall right next to the door, where you would need walking room to get to the "storage" anyway, it is hard to convince an inspector that a room that size can be used for both the panel and storage. Since both rooms are essentially bedrooms, it is also hard to convince an inspector that it won't end up a clothes closet at that size.

I suppose if you ran home runs of Cat6 and coax into the room too, and called it a mechanical or utility room instead of a storage room, then the small size wouldn't matter. But, it is a judgement call or interpretation of the codes by the inspector. If the room was huge with plenty of 'other' walls to put storage shelves on, they usually don't care much about location.

110.26 Spaces About Electrical Equipment. Sufficient access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.

(30" wide × 36")

(B) Clear Spaces. Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.

http://freenec.com/T13.html

.

240.24 Location in or on Premises

(D) Not in Vicinity of Easily Ignitible Material. Overcurrent devices shall not be located in the vicinity of easily ignitible material, such as in clothes closets.

http://freenec.com/T66.html

Passed the final inspection today! Thanks, all.