Electrical

Electrical Subpanel Installation: Expanding Capacity

January 24, 2025

Electrical Team

7 min read

Electrical Subpanel Installation: Expanding Capacity

As your home's electrical needs grow, you might find that your main electrical panel is running out of space for new circuit breakers. A subpanel is essentially a smaller, secondary service panel that is fed from the main panel. It's a common and effective solution for adding circuit capacity for a specific area or project without replacing the entire main panel.

🤔 When Do You Need a Subpanel?

A subpanel is the ideal solution in several common scenarios.

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For a Major Addition or Renovation: A new home addition or a large kitchen remodel will require multiple new circuits. A dedicated subpanel provides the necessary space.

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To Power a Detached Building: When running power to a detached garage, workshop, or shed, a subpanel provides a convenient local hub for circuits and a local means of disconnect.

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When Your Main Panel is Full: If you need to add a new circuit for a hot tub or EV charger but have no open slots in your main panel, a subpanel can provide the needed expansion.

🔧 How a Subpanel Works

The installation is a job for a licensed electrician, as it involves working inside the main panel.

A large, two-pole circuit breaker is installed in the main panel.

A thick cable (typically with four conductors) is run from this breaker to the location of the new subpanel.

The cable is connected to the main lugs inside the subpanel, providing it with power.

New individual circuit breakers for the new area can then be installed in the subpanel.

⚠️ Critical Safety and Code Requirements

Subpanel installation has very specific code requirements, particularly regarding grounding.

In a subpanel, the neutral and ground wires must be kept separate. The neutral bus bar must be isolated (floating), and a separate ground bus bar must be installed and bonded to the panel's metal enclosure. This is different from a main panel and is a critical safety rule to prevent creating dangerous parallel paths for electricity.

Other Key Rules:

The subpanel must be fed by a 4-wire cable (two hots, one neutral, one ground).
It must have enough capacity for the planned circuits.
The installation will require a permit and inspection.

Expanding your home's electrical system requires professional expertise. The Box Advantage Group provides safe and code-compliant subpanel installations to give you the extra circuit capacity you need for your growing home. Contact us to discuss your expansion project.