Running branch circuit to outbuilding -- two circuits there, a 15A
lights and 20A outlet (although it's a 20A breaker, actual usage will
be pretty light, just so happens the old breaker box I'm reusing has
two fixed-amperage breakers that aren't changeable or they would both
be 15's). And no, there's no reason to consider the "expansion down
the road" syndrome here...

Question -- breaker for supply will be 30A single pole about 200 ft or
a little less away. Is 10 ga Cu UF adequate for the distance?