Main Electrical Panel vs. Subpanel: The Difference and Why It Matters

Did you recently discover a second electrical panel in your home? Wondering how it’s different from your main electrical panel?

Well, that second electrical panel is a “subpanel”.

We’ll explain what a subpanel is, how it differs from your main panel and then explore some of the reasons you might want to consider installing a subpanel in your home.

Main vs. subpanels: How they work and how they differ

Every home with electricity has a main electrical panel. The main panel is connected directly to the incoming electricity from your utility company. It distributes that incoming power throughout your home via circuits.

A subpanel, on the other hand, is basically an extension of your main electrical panel. It’s not directly connected to the incoming utility power; instead it feeds off the power from your main panel (think of the subpanel as the “middleman” between the main panel and a branch of circuits in your home).

So here’s the hierarchical flow of electricity as it comes into your home:

Electric meter (power from utility ) > Main panel > Subpanel > Subpanel circuits.

But not every home has or needs a subpanel. Let’s take a look at some of the reasons a subpanel might be installed.

Reasons to install a subpanel in your home

Usually, a single main electrical panel provides enough breakers to feed and protect all of the appliances and circuits inside your home.

But there are times when a subpanel is needed, such as...

When you have circuits/appliances that are far away from the main panel

subpanels can cut down on time and construction (such as the holes that need to be cut into walls to hide/run wiring) when it comes to areas that are far from your main panel such as:

  • Greenhouses
  • Workshops
  • Sheds
  • Add-ons/renovations to home

For example, let’s say your main electrical panel is located in your garage, but you’ve just renovated your home and now need power fed to a room at the opposite end of the home. Instead of running multiple circuit wiring all the way to the new room, you can run a single set of feeder wires to a centrally located subpanel. From there, you’ll need much shorter circuit wiring to feed electricity to appliances.

An example of how long circuit wire runs require cutting holes in the wall.

Having a subpanel that’s closer to the appliances it serves is also more convenient. If an appliance trips one of the breakers in your subpanel, you only have to walk to the nearby subpanel to reset the breaker instead of walking all the way back to the main electrical panel.

When you’ve run out of breaker slots in your main panel

Every main electrical panel has a limited amount of available breakers. If those breaker slots are filled up and you have new circuits or appliances that need power, you may want to consider installing a subpanel (assuming your home still has available power).

If your home has available electrical power but no expansion slots left (seen above), installing a subpanel is a great option.

Before installing a subpanel, you’ll need to determine:

  1. The amount of available power load you’ll need to power your additional circuits
  2. The amount of power your main service has left to offer

One thing to remember is that a sub panel doesn’t increase the amount of available power your home has. If you need an increase in electrical power, that’s an entirely separate problem that would require upgrading your main electrical panel.

Have more questions about main and subpanels?

Have other electrical panel questions that we didn’t answer here? Our Minnesota electricians can help.

Just contact us for all your electrical questions.

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