Wiring a light switch? Here's how. - easy-do-it-yourself Connect the "source" wire to the bottom terminal of the switch and the other black wire to the top terminal. In this picture, you can see the strip gauge on the back of the switch. This gauge is when you want to use the "quick-connect" method when wiring a light switch. Simply strip the wire to the length specified and push the wire into the hole. House Electrical Wiring Connection Diagrams House Electrical Wiring Diagrams: Wiring Connections in Switch, Outlet, and Light Boxes. The following house electrical wiring diagrams will show almost all the kinds of electrical wiring connections that serve the functions you need at a variety of outlet, light, and switch boxes.