A very considerable amount of trade and technical knowledge is required by an electrician. The following are some of the details upon which an inside wireman must have ready and definite knowledge: (1) the methods of installation of electric wires and conduits; (2) the making of electrical connections (fixture wiring); (3) the installation of electrical appliances; (4) the testing of circuits; (5) the methods of computing the sizes of wires; (6) connections and fuses required for specific electrical currents; and (7) the methods of estimating the amount of current required for the specified work. This work presupposes a thorough knowledge of the electrical requirements of the trade as set up by experts, and called the code, together with some knowledge of the theory of electricity, with emphasis on the definition of terms and electrical measurements. Some knowledge of building construction is also necessary.
Electric wiring demands careful insulation from all surrounding material which might under any circumstances become a conductor of electricity. This need for special care in insulating has caused the establishment of definite and fixed rules. It is important that these rules (the electrical code) be understood and observed by the worker, since not only his business integrity and reputation are affected by poor or slipshod work, but the safety of property and even the lives of many people are dependent upon the proper installation of electric wires and appliances.