How to Wire a Light Switch the Old Fashioned Way

Introduction

Wiring a light switch is an essential skill for any homeowner to have. While newer homes use more advanced wiring methods, many older homes still rely on the old fashioned switch wiring technique. This tried and true method has been around for decades and learning it provides a great foundation for working with home electrical systems.

In this comprehensive guide, I'll walk through the entire process of wiring a light switch the old fashioned way step-by-step. You'll learn about the required materials and tools, the different switch wiring diagrams, how to prep the electrical boxes, making safe wire connections, and finally testing your newly wired switch.

Follow along below to gain the knowledge and confidence to wire a light switch like a pro.

What You'll Need

Before getting started, ensure you have all the necessary materials and tools on hand:

Materials

• Light switch - Single-pole toggle switch, rated for your electrical system (15 amps is typical)

• Electrical boxes - Plastic or metal, sized appropriately for your switch and wires

• Cable - 14/2 or 12/2 nonmetallic (NM) electrical cable with grounding wire

• Wire connectors - Twist-on wire connectors or wire nuts

• Wire strippers - For stripping insulation off wire ends

• Electrical tape - For covering stripped wire

Tools

• Voltage tester - For safely checking wires

• Screwdrivers - Standard and Phillips head

• Drill/driver - For drilling holes and driving screws

• Drywall saw - For cutting drywall access holes

• Stud finder - For locating wall studs

• Flashlight - For seeing inside electrical boxes

Switch Wiring Diagrams

There are a few different ways to wire a light switch, but the most common methods are:

Power Through Switch

This method routes electrical power through the light switch first before going to the light fixture.

Power to Light First

With this method, power goes to the light fixture first, and a switch loop is added to control it.

Three-Way Switch

Allows lights to be controlled by two separate switches.

The example diagrams show the basic concept for each method. The exact steps will vary slightly depending on your specific application.

Prepping the Electrical Boxes

With the basic wiring diagrams in mind, we can start prepping our electrical boxes:

1. Shut Off Power

Safety first! Turn off power to the circuit at the breaker box before working.

2. Install Switch Box

• Mark the desired height and location for the switch box on the wall.

• Cut away drywall with a drywall saw to expose wall stud.

• Mount the metal or plastic switch box securely to the stud with screws.

3. Install Light Box

• Locate the ceiling joist for the light fixture using a stud finder.

• Mark the mounting location and cut a hole for the electrical box.

• Securely mount the light box.

Making Safe Wire Connections

With the boxes installed, we can focus on connecting up the wiring:

1. Run Cable Between Boxes

• Drill access holes between the switch and light boxes.

• Run the electrical cable between the boxes through the holes.

• Allow plenty of extra wire length for connections.

2. Attach Cables

• Secure the cables by attaching the metal clamps inside each electrical box.

3. Strip Wires

• Strip away 3/4" of insulation from each wire end using wire strippers.

• Wrap exposed copper with electrical tape to avoid short circuits.

4. Connect Wires

• Refer to the wiring diagram for your specific application.

• Match up wires and attach using twist-on wire connectors.

• Ensure connectors are tightly secured.

Testing and Finishing Up

We're now ready to test out our newly wired switch:

1. Turn Power Back On

• Turn the breaker back on to restore power to the circuit.

2. Test Switch

• Flip the switch on and off and test that the light turns on and off correctly.

• Use a voltage tester to confirm power is flowing properly.

3. Install Devices

• Mount the switch in the switch box and screw into place.

• Install the light fixture in the ceiling box.

• Attach the cover plates.

4. Caulk and Cover

• Add caulk around the boxes to seal gaps.

• Patch drywall if needed and add paint to match the rest of the wall.

And that covers everything needed to wire a basic light switch the old fashioned way. Taking the time to follow each step carefully results in a safely wired switch that lasts for years to come.

Common Questions

What wire gauge should I use?

• For most basic residential wiring, 14 AWG or 12 AWG copper wire works well. Larger gauge is better for longer wire runs.

Can I use the push-in connectors instead of twist-on?

• Twist-on wire nuts provide a more secure connection, especially for beginners. Push-in connectors can loosen over time.

What causes my new light switch to not work?

• Check for loose wire connections, incorrect wiring order, faulty switch, or incorrect power, neutral, and ground connections.

How do I add a light switch to an existing light fixture?

• Turn power off, run 14/2 cable from fixture to new switch box, cut in switch box, then follow wiring diagrams to make new connections.

Hopefully this overview gives you the knowledge needed to install a light switch like a pro. Always exercise caution and turn power off before wiring. Contact a licensed electrician if you have additional questions or concerns.