How to Safely Wiring a Double Gang Box

Introduction

Wiring a double gang box allows you to have two switches controlling two separate lights or outlets from one box. While this can be a useful way to consolidate controls, it's important to wire it properly for safety. In this guide, I'll walk you through the steps I take to safely wire a double gang box.

Gather Materials

Before starting any electrical project, it's essential to have the right materials on hand. Here's what you'll need to wire a double gang box:

• Double gang box - This provides twice the space of a single gang box to accommodate two sets of wires. Make sure it's rated for the number of wires you'll have.
• Switches - Standard light switches, usually single-pole. Get one for each circuit you're controlling.
• Wire nuts - To connect the wires. Get the right size for the gauge of wire you're using.
• Electrical tape - Helps insulate wire connections.
• Appropriate gauge wire - For most residential lighting, 14/2 wire is sufficient. Using thick enough wire prevents overheating.
• Cable clamps - Secures the wires entering the box and prevents strain.
• Screws - To mount the switches and secure them to the box.

Turn Off Power

Before touching any wires, use a voltage tester to confirm the power is OFF at the circuit breaker. Working on live wires can result in a serious shock hazard. Better to take a minute to flip the breaker than get injured.

Mount the Box

If this is a new install, start by mounting the double gang box between two wall studs. The box should be flush with the wall surface so switches mount properly. Secure box to studs with appropriate screws.

For existing boxes, remove old switches and disconnect all wires before installing the new double gang box. Mount the new box in the same spot as the old one.

Run and Connect the Wires

Here's how I wire a double gang box to control two separate lights:

• Run 14/2 Romex power feed wire from breaker to the box.
• Run a 14/2 wire from the box to each light fixture.
• One set of wires controls the "LINE" or power supply. Connect these to one switch.
• The other wires control the "LOAD" going to light fixtures. Connect to the second switch.
• Use wire nuts to connect LINE hot, neutral, and ground wires to the feed wire.
• Connect LOAD hot wires to the switches.
• Connect all ground wires together in the back of the box.

Follow diagrams properly to know which wires splice together with LINE vs LOAD.

Install the Switches

With the wiring complete, install the switches into the box:

• Strip the ends of the two LOAD hot wires and connect one to each switch terminal.
• Screw the switches into the double gang box. Make sure they are level and seated firmly.
• Attach the switch plate cover.

Testing and Use

Before closing up the wall, test that both switches work properly:

• Turn power back on at the breaker.
• Flip each switch separately to verify the correct lights turn on and off.
• If lights don't work, turn off power and re-check all connections.
• Once lights function properly, push any excess wire back into box and close up wall surface.

And that covers the basics of safely wiring a double gang box! Let me know if you have any other questions. Stay safe when working with household electrical.