Well, it's been a while but last time I replaced a breaker I noticed they had used the same gauge wiring for the 15 and 20 amp circuits. House was built in 88 and never had a problem with the copper wiring. Now when I had MH/T5 and more things on that circuit it was a different story. The wiring was fine, but the circuit breaker sometimes would get hot and trip usually in the heat of summer when the garage got really hot.Won’t just switching the breaker just cause the wire to overheat?