Want More Outlets? Learn How to Add a Subpanel

Is your home’s electrical system constantly overloaded? Do you find yourself needing more outlets but lack space on your main circuit breaker panel? Adding a subpanel is the solution. A subpanel provides extra capacity by allowing you to add more circuits in a secondary breaker box. With some planning and basic electrical skills, installing a subpanel is a doable DIY project for many homeowners.

You’ll learn how subpanels work, what’s involved in adding one, and key steps for a safe, successful installation. Let’s get started and shed some light on how to add a subpanel.

how to add a subpanel

Why Add a Subpanel?

There are several good reasons you may want to add a subpanel to your home’s electrical system:

  • Provide more circuits and outlets – A subpanel lets you add extra breaker spaces and wire up new outlets wherever needed.
  • Upgrade older electrical systems – Homes built prior to 1960 often have outdated 60-amp electrical service. A subpanel can provide modern 100+ amp capacity.
  • Support new additions and renovations – When finishing a basement or adding on, a subpanel easily handles the new electrical demands.
  • Prevent overloads and tripped breakers – Reduce nuisance circuit breaker trips by segregating some circuits to the subpanel.

If your main breaker panel is full, it’s time to consider a subpanel installation. This project can improve your home’s electrical capacity, flexibility, and safety.

Subpanel Basics

What is a Subpanel?

A subpanel, also called a subfeed panel, is a secondary electrical distribution point that branches off from a main circuit breaker panel. It contains additional breaker spaces to add new circuits as needed. A subpanel allows extra circuits to be conveniently added without replacing or reconfiguring the main service panel.

Subpanel vs Main Panel

The main electrical panel connects your house to the incoming utility power lines. It contains the main breaker that controls power to the entire home. A subpanel branches off the main panel, housed in a separate nearby enclosure. The subpanel provides supplementary breaker capacity for a localized group of electrical circuits.

Subpanel Parts

A basic subpanel consists of the following components:

  • Enclosure box – Houses the subpanel parts and breakers.
  • Ground and neutral bus bars – Provide attachment points for wires.
  • Circuit breakers – Protect and control individual circuits.
  • Interconnecting wires – Feed power from the main panel.

Subpanel Planning

Calculate Electrical Load

Before selecting and installing a subpanel, it’s important to calculate your home’s total electrical load. Review the number and types of existing circuits in the main panel. Then factor in any new circuits you plan to add. Allow for future expansion needs too. Your electrician can assess your electrical requirements and help determine the appropriate subpanel size.

Choose a Location

Subpanels don’t have to be installed right next to the main panel. Many homeowners opt to locate them in the garage, basement, or a utility room. Choose an accessible spot where it makes sense to group the subset of circuits controlled by the subpanel. Try to position it close to where the new circuit wiring will run.

Select a Subpanel Size

Size your subpanel to comfortably handle the expected electrical load you calculated. Leave some extra breaker spaces for unanticipated future needs. 100 amps is adequate for subpanels in many small to medium-sized homes. Follow your local electrical code requirements based on your home’s total load.


Most jurisdictions require an electrical permit before installing a subpanel. This allows an inspector to check that the subpanel is properly setup and wired. Making sure you have the right permits avoids potential issues down the road.

Subpanel Installation

Once you’ve completed the planning and preparation, it’s time to tackle the subpanel installation. Follow these key steps:

Turn Off Main Power

Safety first! Locate your main circuit breaker panel and flip the main breaker to the off position. This cuts power to the entire house electrical system. Double check with a voltage tester that the power is off before proceeding.

Mount Subpanel

Determine the exact mounting location based on your earlier planning. If installing in a wall, cut an appropriate sized opening. Securely fasten the subpanel enclosure using supplied or appropriate fasteners.

Run Conduit and Wires

Plan your routing from the main panel to the subpanel location. Install proper gauge wires in an approved conduit between the two panels. Carefully pull the wires through the conduit leaving plenty of slack on each end.

Connect Wires

Electrical code requires using 4 wires between the main and subpanel. Attach the ground wire to the ground bus bar in the subpanel. Connect the neutral wire to the neutral bar. Finally, attach the hot wire(s) to the branch circuit breakers in the subpanel.

Install Breakers

Snap in the appropriate circuit breakers according to your plan. Clearly label each circuit at the subpanel. Take time to logically organize all the new circuits.

Inspect and Power Up

Call for an inspection to verify proper subpanel installation before turning the power back on. Once approved, flip the main breaker back on. Carefully test each new circuit on the subpanel to confirm correct operation.

Subpanel Safety Tips

Any electrical project comes with hazards, so safety should be your top priority when installing a subpanel:

  • Follow all electrical codes to the letter – Improper wiring can injure you or create a fire risk.
  • Turn off power at the main breaker – This single step eliminates the biggest shock risk.
  • Wear personal protective equipment – Protect your eyes and hands when working with wires.
  • Connect wires securely – Loose connections can arc and overheat.
  • Double check connections – Confirm proper installation of all wires and breakers.
  • Hire electrician if unsure – If you lack confidence, have an expert handle the tricky wiring.

Stay safe! Adding a subpanel should upgrade your electrical service, not compromise it.

Subpanel vs Electrician

Is installing a subpanel a DIY project, or is it better left to the professionals? Here are a few things to consider:

  • DIY if you have electrical experience – Adding a basic subpanel isn’t too hard for a seasoned DIYer.
  • Electrician best for large or complex installs – If the subpanel will be 100+ amps or servicing your whole house, hire help.
  • Professional can ensure proper setup – Licenced electricians are experts at meeting code and safety requirements.

Get quotes from licensed electricians if you are unsure about taking on the subpanel project yourself.

A subpanel opens up options for all sorts of future electrical expansion. Here are some examples of what a subpanel could support down the road:

  • Install EV charger – Dedicate a high amp circuit for charging electric vehicles.
  • Add pool equipment circuits – Safely power pumps, heaters, and filters.
  • Support home battery storage – Integrate solar and backup battery systems.
  • Accommodate smart home tech – Supply power for home automation systems.

Careful subpanel planning and installation today allows seamless electrical upgrades tomorrow. Now you have the knowledge to evaluate your needs and take on an impactful, budget-friendly subpanel project.

Determining the location of the new subpanel: Before adding a new subpanel, it’s essential to identify the best location for it. Some factors to consider while choosing a location include the distance between the new subpanel and the main panel, the proximity to the electrical equipment that requires power, and the availability of space for the new subpanel.

Calculating the required electrical capacity: Before adding a new subpanel, it’s crucial to determine the electrical capacity required for the new circuits. This calculation will depend on the number of circuits, the type of equipment to be powered, and the distance between the new subpanel and the main panel.

Obtaining the necessary permits: Depending on the location, it may be mandatory to obtain building permits before installing a new subpanel. It’s essential to check with the local authorities regarding this requirement.

Choosing the right subpanel: Selecting the right subpanel is critical to ensure that it meets the electrical requirements of the new circuits. Some factors to consider while choosing a subpanel include the number of breakers required, the type of equipment to be powered, and the distance between the new subpanel and the main panel.

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