It is a dedicated line ran to garage for previous owners air compressor. Fuse box in garage reads amps-30 volts-125/250 pole-3sn #10 wire size

Yes, but your post is not quite clear as to what you have now.
What type of breaker do you have in the main panel? Do you have a single breaker or do you have a double breaker? What type of wire do you have 10/2 or 10/3?
Where does this line go, to an outlet or to a sub panel?