Electrical Basics ~ Residential Wiring Diagrams

Wires... Mysteries Revealed!

Keeping in mind that the "source" is both, the starting point and the return point of an electrical circuit, you can use that knowledge to map any wiring situation. Below, we'll go through the more common wiring scenarios that a homeowner may run into.

The easiest way to use the wiring diagrams, is to simply trace the circuit with your finger or a similar item. Each switch, outlet and fixture is connected using a cable/ raceway. Just as they'd be in your home.

The yellow dots represent, connections made using wire nuts. The "source" indicates "power in" from the electrical panel for example. This is where you want to start with your finger...trace the electrical currents path, along the circuit to the load and back. Of course, your eyes might do the trick here as well. It's completely up to you!

NOTE: The ground/grounding conductors have been eliminated for clarity. If your system carries a ground, then pigtail, out a lead to bond each switch and or outlet. And then tie the grounds through, at each box. If the boxes are metal, you'll need to provide a pigtail to bond them as well.

Wiring Diagrams ~ The Single Pole Switch...

At the switch, you have power in from the source. The hot/black wire hits the switch and the neutral/white wire is fed through to the light. This provides the currents path back to its source. The cable ran out to the light, is called a "switch leg". The hot/black wire from the switch leg connects to the other pole on the switch. Connect the fixture to the switch leg, color to color..

Wiring Diagrams ~ The Three Way Switch...

At the first three way switch, you have power in from the source. The black/hot wire will connect to the "common" screw. Then, each three way switch is tied together, using a 3 wire NMB cable. These wires are called the "travelers." This cable will carry power on either the red or black conductors, depending on the position of the switch. The red and black wires will connect to the 2 brass colored screws. The order does not matter. Lastly, the neutrals simply feed through.

At the second three way switch, you have the travelers, again hitting the brass screws. Out from this three way switch, runs the switch leg to the light. The black wire will connect to the common screw. The neutrals will feed through to the fixture. Connect the fixture to the switch leg, color to color.