How To Install a New Basement Circuit

Installing a new circuit in your basement can help prevent overloaded electrical systems and save you from frequent breaker trips. This guide will walk you through the steps of safely installing a new 20-amp circuit, following the advice This Old House master electrician Heath Eastman shares in the video above.

Understanding the Problem With Circuits

Overloading a circuit often happens when too many high-power appliances are connected. This is often the case in older homes where kitchen and basement circuits are interconnected.

Eastman identifies several common issues contributing to the problem:

• Multiple appliances (coffee maker, toaster, and dehumidifier) on the same circuit
• Undersized wiring for the circuit amperage
• Lack of proper grounding and ground fault circuit interrupter (GFCI) protection
• Use of extension cords for permanent appliances

Addressing these issues requires installing a dedicated circuit for basement appliances, using a proper wire gauge, and upgrading to code-compliant outlets and breakers.

Symptoms of an Overloaded Circuit

Signs that your circuit may be overloaded include:

• Frequent breaker trips
• Dimming lights when multiple appliances run at the same time
• Buzzing sounds from outlets or switches
• Warm or discolored outlets

If you notice any of these symptoms, it is crucial to evaluate your electrical circuit capacity to prevent potential hazards.

Planning the New Circuit Installation

Proper planning is key before you start installing a new circuit. This includes:

• Assessing the electrical load requirements
• Determining the best route for running new wiring
• Selecting appropriate materials and tools
• Obtaining any necessary permits

Eastman recommends installing a new 20-amp circuit specifically for the basement appliances. This will alleviate the load on the existing kitchen circuits and provide dedicated power for the dehumidifier and other basement equipment.

Assessing Electrical Load Requirements

Accurately calculating your electrical load requirements helps you avoid future overloading. Add up the wattage of all appliances intended for the new circuit to make sure they don’t exceed the circuit’s capacity. For instance:

• Dehumidifier: Average 400 watts
• Coffee maker: Around 800–1200 watts
• Toaster: Approximately 800–1500 watts

Materials and Tools Needed to Install a Basement Circuit

To install a new basement circuit, you’ll need the following materials and tools:

• 20-amp GFCI breaker
• 12/2 electrical wire
• Cordless jigsaw
• Conduit and fittings
• Crown stapler
• Electrical outlet and cover plate
• Electrical staples and running boards
• Electrical outlet tester
• Hammer drill for masonry work
• Metal electrical box
• Screwdrivers and drill
• Screws
• Wire strippers and cutters

Additional Tools for Specific Situations

Depending on your basement’s setup, some additional tools might be required:

• Fish tape: For pulling wire through conduit or walls.
• Label maker: Helps in marking circuits and wires for future reference.
• Cable ties: To manage and organize cables neatly.

Safety Precautions When Installing an Indoor Circuit

Working with electricity can be dangerous. Before beginning any electrical work, follow these precautions:

• Turn off power to the area at the main breaker panel
• Use a voltage tester to confirm power is off
• Wear appropriate personal protective equipment
• Follow all local electrical codes and regulations

If you’re unsure about any aspect of the installation, consult a licensed electrician.

Step-by-Step Circuit Installation Process

Remove the Existing Outlet

First, follow these steps to remove the original device:

1. Shut off the power to the existing circuit at the breaker panel.
2. Test the outlet with a voltage tester to verify that it’s not energized.
3. Track the existing device’s wiring back to a junction box.
4. Disconnect the existing device’s wires from the wire nuts to remove it from the circuit.
5. Reinstall the wire nuts and close up the junction box.
6. Remove the existing outlet if necessary.

Install the New Junction Box

Eastman then demonstrates how to install a new junction box in the basement:

1. Choose a suitable location on the basement wall.
2. Place the outlet against the wall and mark the screw locations.
3. Use the hammer drill and masonry bits to drill into the block wall, and use masonry screws to fasten it.
4. Choose a knockout hole, tap it open, and install a cable clamp.

Run New Wiring

If necessary, install running boards across the floor joists overhead from the outlet’s location back to the electrical panel. It’s best to make the run as straight as possible.

Then, follow these steps to run the new wiring from the panel to the outlet:

1. Run 12/2 wire from the new outlet location to the electrical panel. Run it straight up from the box and down the length of the running board, and leave enough slack at both ends for connections.
2. Secure the wire to the running boards using staples, ensuring it’s not pinched or damaged.

Make Connections at the Panel

Shut off the main breaker to the panel, remove the panel cover, and test the wires below the breaker to ensure that the panel is dead. Then, choose a location for the new breaker and find a knockout on the side of the panel box that makes the most sense. Tap the knockout hole open and insert a cable clamp in the hole. Run the wire through the panel, leaving the end long.

Install the new breaker by fitting the hooks in the panel over the tab on the breaker. Once hooked, press down firmly on the breaker to clip it into place on the main bus bar. Extend the pigtail wire and attach it to the neutral bar.

Cut and strip the wire to length at the panel, then make these connections:

1. Connect the black (hot) wire to the breaker.
2. Connect the white (neutral) wire to the neutral bar.
3. Connect the ground (green) wire to the grounding bar.

Wire the New Outlet

At the new junction box:

1. Cut the wire to length at the outlet side. Leave it around 12 inches long.
2. Slide the end of the wire through the cable clamp, strip the jacket, and strip the ends of the individual wires.
3. Bend the ends of the wires into small hooks.
4. Place the black wire over the new outlet’s gold screw, the white wire over the silver screw, and the green wire over the green screw. 
5. Tighten all the screws. 
6. Wrap the outlet with electrical tape and install the outlet in the junction box.
7. Finish securing the wire to the running boards with wire staples.

Testing and Finalizing

With everything secure, reinstall the panel cover. Shut off all the individual breakers, flip on the main breaker, and then re-energize each breaker one at a time. Test the new outlet with a pen tester before installing an outlet cover.

Code Compliance and Considerations when Installing a Circuit

When installing a new basement circuit, keep these code requirements in mind:

• Use 12-gauge wire for 20-amp circuits.
• Install GFCI protection for basement outlets.
• Check for proper grounding for all components.
• Follow local regulations for conduit use and wire protection.

Always check with your local building department for specific code requirements in your area.

The Importance of GFCI Protection

GFCI outlets protect against electrical shocks, especially in areas like basements where moisture tends to be present. They also help reduce the risk of electrical fires and protect appliances from damage.

Circuit Installation Cost Considerations

The cost of installing a new basement circuit can vary depending on factors such as:

• Length of wire run
• Type of materials used
• Complexity of the installation
• Labor costs (if hiring a professional)
• Permitting required
• Added upgrades, such as surge protectors or arc-fault circuit interrupter (AFCI) breakers

On average, homeowners can expect to pay between $570 and $1,100* for a professional installation. DIY installations may cost less but require careful attention to safety and code compliance.

*Cost information is based on 2024 data from Angi.

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