Electrical Codes for Home Electrical Wiring Wiring Methods for Conductors and Screw Terminal. Only one conductor shall be installed under a terminal screw. In boxes with more than one ground wire, the ground wires shall be spliced with a wire tail or pig tail attached to the grounding terminal screw of the device. Basic Residential Electrical Wiring Rough In and Codes Guide If you are going to do electrical wiring, you should become educated about the code as it applies in your area. Service Equipment The Service equipment (main panel, entrance conductors, meter base, and associated hardware) must be adequate to safely supply the required load.