How to Splice Household Wiring to Extend Circuits - Do-it Wire splice connections must be housed inside a covered electrical box, known as a junction box. A junction box is usually square and made of metal. When installed, the box must not be concealed inside walls or ceilings so it remains accessible at all times. Light Switch Wiring Diagrams - Do-it-yourself-help Wiring a Switch to a Wall Outlet Here a receptacle outlet is controlled with a single-pole switch. This is commonly used to turn a table lamp on and off when entering a room. In this diagram, 2-wire cable runs between SW1 and the outlet.