I no longer am dealing with my contractor. Long story. But he ran 2 10-3 wires out to my garage for power. I think he was planning on putting a 30 amp breaker on the panel in the house for each wire and a sub panel in the garage for each wire. Is this OK to do? If so, what kind of sub panel should I get? How many breakers can run on each sub panel?
You or your contractor have gone about this backwards. The first step is to determine your electrical requirements, including a reasonable amount of future expansion. Then you can size the wire & breaker together to meet those requirements.