200 amp service-2/0 cu thw
We are replacing an old main box on the house that does not have a main breaker. The box is opposite the meter pan. Meter pan is on outside and there is a short nipple and then the main box is on the inside of the same wall. Old box had no main breaker. New box has 200 amp breaker. Underground service to meter pan is 4/0 aluminum. Wire between meter pan and main box is 2/0 cu thw. Do I need to upgrade this to 2/0 thhn cu or is it ok to leave this old wire? Thanks in advance.