I am rewiring an out building and am concerned about the size of the overhead feeder wire. I have aluminum triplex feeder wire with 7 strands of wire for each line. Is this wire heavy enough to carry 200 amp service?

Written on the cable will be the AWG of the cable, from the AWG size we can determine the current flow the cable can support.

Have you calculated the Voltage drop? How far will the cable have have to go to reach the out building?