The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Practical Electricity And House Wiring

Wire Sizes Required by Code.—The Code requires certain minimum sizes of wire, depending on the full load current in amperes of the motor, as stamped on its name plate.

Note that the above specifies merely the minimum requirement, and it is frequently necessary to use heavier sizes as will be covered later.

Maximum Fuse Size.—The Code also has some very definite requirements as to the maximum size fuse permitted in the branch circuit serving a motor of any given amperage as stamped on the nameplate of the motor, the following table covering single-phase A. C. motors. It is recommended that only the time-lag type of fuse be used to protect motors. This type of fuse will carry the high amperage consumed by the motor while starting, without blowing, and still will blow just as quickly as an ordinary fuse if a continuous overload, which would damage the motor, is flowing.

Proper Wire Size.—If the motor is located some distance from the service switch, you will have to take into consideration also the voltage drop and use wires larger than the minimum required by the Code. In general, if you will follow the table below, you will be on the safe side.