A breaker or fuse is referred to as an over-current protection device. It is recommended that the homeowner turn all circuit breakers on and off manually and make sure they are in functional condition.
The rating of the fuse or circuit breaker for each branch circuit may be checked by a home inspector or electrician. The amperage of the fuse or circuit breaker should not exceed the capacity of the wiring in the branch circuit it protects.
Most household circuits are wired with #12 copper wire, which should have 20-amp protection. Large appliances, such as electric water heaters and central air conditioners, may require 30-amp service, which is normally supplied by #10 copper wire. An electric range requires a 40- amp or 50-amp service with #6 copper wire. Breakers (unless otherwise designed) should have only one wire attached to the breaker. Any changes or variations should be evaluated by and if needed repaired by a licensed electrical contractor.
Information used in this article was provided and used with permission by Internachi. www.internachi.org