When upgrading the power capacity at your home, you may find that your service panel can't accommodate a new circuit breaker. If you need this extra power kick, a subpanel could be the answer. A subpanel connects to your home's main service panel via a durable, multi-wire cable. But wiring a subpanel is a dangerous project that should only be completed by homeowners with extensive knowledge of electrical systems. If that sounds like you, read on to learn how to wire a subpanel for your home.
Preparing to Wire a Subpanel
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This DIY project involves meticulous preparation if you're serious about taking it on yourself. That's because a poorly done job comes with safety and liability risks. Start by consulting with a licensed electrician near you who can act as an inspector to confirm that conditions are safe for installing a new subpanel. If you skip this step, there's a risk that you're going to strain your home's electrical system, which could cost you in electrical repairs down the road.
An electrician is also important because they can assist with obtaining a permit for adding a subpanel. Once your project is done, the electrician can return to verify that the work you've done is up to code.
You can also ask your electrician what they recommend for the new subpanel’s amperage. If you have a newer home, you should be fine with a panel offering 100 to 200 amps. However, an older home may only be capable of supporting a 60-amp subpanel.
Buy Your New Subpanel and Shut Off Main Breaker
You can buy a new subpanel at a local hardware store. Make your life easier by choosing a model that comes with the breakers, four-wire feeder cables, and connectors needed for installation. Never use a secondhand subpanel to try to save money. For the sake of your safety, this needs to be an out-of-the-box purchase.
But the most important part of preparing to wire a subpanel, again, is safety. Like any home project involving electrical work, wiring a subpanel requires you to shut off the main breaker in your service panel. Remember, if you don’t have prior experience with electrical wiring, your safest and most practical option is to hire a professional electrician.
Mount Your New Subpanel
When mounting your new subpanel, position it roughly a foot away from your home's main service panel. Running a stud finder across the wall, find a stud in a spot where you want to install your panel. Place the subpanel against the wall to mark with a pencil the spots where the four mounting screws will be placed.
Placing your panel at a height of about 5 feet will make it easy for you to access the panel without it being reached by children or pets. However, your town or city may have local building codes that require you to mount your subpanel at a specific height.
Next, drill your screws into the stud while leaving a small gap between the wall and each screw to allow your subpanel to be mounted. Finally, place your subpanel onto the mounting screws. Tighten the screws before giving the panel a good shake to confirm that it's secure.
Plan Your Wiring Route
Professional electricians consider the wiring route to be one of the most important parts of how to wire a subpanel properly. That's because a properly wired panel should have neat paths around the perimeter to indicate which wires go to various breakers. In addition to creating a clear, easy system that will help with repairs or updates in the future, a proper wiring route also helps to prevent a fire hazard by reducing the likelihood that unwieldy wires will brush against hot bus bars.
To complete this step, the ground wire, neutral wire, hot black wire, and hot red wire all need their own route plans.
Strip Your Wires
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Strip your red and black wires to expose their metal wiring. The red and black wires need to be connected to your feeder breaker by being inserted into the slots located beneath the two top screws. Make sure the screws are tightened on the connections to keep the newly placed wires secure once this is done.
Connect Your Wires
In this next step, you need to remove the knockout slug from the panel using a hammer. You can find this perforated plug on the top, side, or bottom of the panel. With the plug knocked out, you can insert wiring into your subpanel. Some plugs can be stubborn. In this case, you may need to tug at the plug with pliers.
Once the knockout plug is gone, insert your metal connector into the hole to help accommodate the four-wire feeder cable that needs to be pulled through. Here's a cheat sheet for where wires connect:
Black and Red Wires: Hot bus bars
Neutral Wire: Main neutral terminal
Ground Wire: Ground bus bar
Install Your Feeder Breaker
Once the feeder breaker is connected to the red and black wires, it needs to be placed inside the empty slot in the main panel. Do this slowly and gently without forcing the fit. You will know that the feeder is in place when you feel a slight "click."
Test the Panel
Once you're confident that all of the connections are securely in the right configurations, it's time to restore your main panel's power. Turn on the feeder breaker to see if your panel is functioning. If nothing happens, congratulations—you've installed your subpanel correctly. While your subpanel may turn on, it's important to remember that there's always a chance that it was installed incorrectly if this was a DIY project. Don't hesitate to call a licensed electrician to come inspect your work before using your new subpanel.
DIY vs. Hiring an Electrician
The cost to install a new subpanel in your home is between $150 and $300 if you do it yourself, as you’ll only have to pay for the cost of the subpanel itself.
Most homeowners prefer to pay the cost for professional installation because they want the reliability and peace of mind that an experienced electrician can bring to the job. Most electricians charge between $530 and $1,940 to install a subpanel. That extra money is well worth the cost, though, as electrical repair is a risky DIY project for typical homeowners.
Frequently Asked Questions
Subpanels are important for easing the load on your home's main circuit breaker. They can prevent dangerous overloading that causes tripped breakers or melted fuses. You can also use a new subpanel to divide the electrical load in different parts of your home. Most people install new subpanels when increasing electrical needs in a home. Examples would be adding a home theater, wiring a new hot tub, or adding more electronics.
While local requirements vary, many towns and cities require you to obtain permits when making changes of any size or scope to your home's electrical configuration. A new subpanel is generally subject to all electrical panel location rules and clearance requirements. Be sure to check your local requirements before getting started.
Scott Dylan Westerlund has been writing about homes and real estate for almost ten years. In addition to Angi and HomeAdvisor, he's written for Today's Homeowner, Homedit.com, Flyhomes, and HomeLight.
Scott Dylan Westerlund has been writing about homes and real estate for almost ten years. In addition to Angi and HomeAdvisor, he's written for Today's Homeowner, Homedit.com, Flyhomes, and HomeLight.
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