Breaker Box Safety: How to Connect a New Circuit

Add a new circuit to your home's wiring

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Next Project
Time

A full day

Complexity

Advanced

Cost

$51–100

Introduction

Adding a new circuit can be a daunting and even dangerous job. We show you how to do it with step-by-step instructions and important, life-saving safety tips.

Tools Required

  • Flashlight
  • Needle-nose pliers
  • Pliers
  • Utility knife
  • Voltage tester
  • Wire stripper/cutter

Materials Required

  • AFCI circuit breaker
  • Cable clamp
  • electrical staples

Know What You’re Getting Into

We believe in safe DIY. That’s why we’ve always been reluctant to show readers how to open a breaker box and connect a new circuit. Even with the power shut off, there’s a chance you could touch the wrong parts and kill yourself. But then we figured if we didn’t show you, you’d just go search it somewhere else. And that scared us even more. So we’re going to walk you through the process, showing you the safest way to open the breaker box, wire a new breaker, and test your work.

Opening the main circuit breaker panel box and adding a circuit is actually pretty easy. You only have to connect three wires to add a circuit, and each circuit wire is color-coded. But there are some safety precautions, and if you ignore them, you could kill yourself. Really. If you follow our safety steps in order and to the letter, you’ll be fine. But if at any point you’re unsure how to proceed or feel uncomfortable with the project, call an electrician.

Stay away from the large wires and lugs. They’re always live, even with the main breaker (service disconnect) shut off. If you touch them, you could die. Cover the live areas with a cardboard shield to prevent accidental contact while adding a circuit. If you have any doubts about which areas stay live, contact an electrician. There’s a reason awareness of electrical issues is a key step in preventing fires in the home.

Watch this video to see the safe way to connect a new circuit yourself:

Get the Right Parts and Tools

Before you go shopping, open the door of your breaker box and copy the manufacturer’s name, the box model number, and the style numbers of the breakers that are approved for your box. Then buy one of those breakers. If your home center doesn’t sell the right model or brand, you’ll have to go to an electrical supplier. You cannot install a circuit breaker style that isn’t specifically approved for use in your box — even if it fits inside the box.

While at the store, pick up a few 1/2-inch plastic snap-in cable clamps to secure the new cable. They’re safer than metal clamps because you don’t put your hand in the panel to install them.

If you need a reminder about how bad some amateur electrical can be, check out this list of the most common electrical code violations.

You have to shut off the power to your whole house, so you’ll need a powerful work light. An LED headlamp is also a great idea so you won’t have to juggle a flashlight, wire strippers and a screwdriver. Round up a utility knife, wire strippers, electrical tape, a circuit tester (not a voltage sniffer), and a flat-blade screwdriver or No. 2 square-drive tip for your multi-bit driver. These are the two must-have tools for DIY electrical work.

Project step-by-step (12)

Step 1

Get the Right Parts and Tools

Before you go shopping, open the door of your breaker box and copy the manufacturer’s name, the box model number, and the style numbers of the breakers that are approved for your box. Then buy one of those breakers. If your home center doesn’t sell the right model or brand, you’ll have to go to an electrical supplier. You cannot install a circuit breaker style that isn’t specifically approved for use in your box — even if it fits inside the box.

While at the store, pick up a few 1/2-inch plastic snap-in cable clamps to secure the new cable. They’re safer than metal clamps because you don’t put your hand in the panel to install them.

If you need a reminder about how bad some amateur electrical can be, check out this list of the most common electrical code violations.

You have to shut off the power to your whole house, so you’ll need a powerful work light. An LED headlamp is also a great idea so you won’t have to juggle a flashlight, wire strippers and a screwdriver. Round up a utility knife, wire strippers, electrical tape, a circuit tester (not a voltage sniffer), and a flat-blade screwdriver or No. 2 square-drive tip for your multi-bit driver. These are the two must-have tools for DIY electrical work.

An Inside Look at Your Main Breaker Panel

Your main breaker panel might not be exactly like the one here. With any panel, find the large cables and the lugs they’re connected to. They’re the parts that are always live, even when the main breakers are switched off. Here’s how to know what’s what:

  • A: Main lugs. They’re always live — even when the main breaker is off. NEVER TOUCH THEM.
  • B: Main cables. The black ones are always live. And although they’re insulated, avoid touching them.
  • C: Main breaker. Always switch it off before removing the panel’s cover.
  • D: Breaker. The hot wire (usually red or black) from each circuit connects to a breaker. If you’re installing an AFCI breaker (as shown on the following pages), you’ll also connect the neutral wire to the breaker.
  • E: Breaker bus. Distributes power from the main breaker to the individual circuit breakers. Each breaker snaps onto the bus.
  • F: Neutral bus. All ground and neutral (white) wires connect here. If you’re installing a standard breaker, the neutral (white) wire connects here, too. If you’re installing an arc-fault circuit interrupter (AFCI) breaker, you’ll connect the neutral to the breaker and run a “pigtail” wire to the neutral bus.
  • G: Breaker space. This panel has room for three more breakers. You can install your new breaker in any open space.

Plus: Check out these 11 real-life epic electrical fails.

An inside look at your main breaker panelFamily Handyman

Step 2

Your Main Breaker Panel Might Look Like This

The photo shows a different configuration where the large cables and lugs are located on the right-hand side of the circuit breaker box, rather than at the center.

Main Breaker PanelFamily Handyman