I think most states use the same basic electrical code. In Calif the total of the breakers can add up to 165% of the rating of that box. The box itself may not have a main breaker, but it will be running off a 50 amp breaker in the main service panel.
That means all the breakers in that sub-panel can add up to about 80.
Believe it or not, they assume you are not going run everything you own at the same time. Even if you did, that is what the breakers are for.
