How Big Of A Subpanel Can I Install Off A 100 Amp Service?

Upgraded Home Team
by Upgraded Home Team

If you want to add more circuits to your home but don’t have room in your pane box, a subpanel makes expansion possible. It’s a common problem, especially in older houses, not to have enough spaces in your breaker box. If you choose to add a subpanel to your home, it’s important to know your limitations.

If you have a 100-amp service in your home, you can install a subpanel up to double its size. That means that you can install a subpanel of up to 200 amps of a 100-amp service. The most important thing with your subpanel is that it is properly installed with safety in mind.

There’s much more to know about subpanels before you decide to install one, however. This article will inform you about the most important things to know before installing a subpanel.

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What is a Subpanel?

A subpanel is an additional panel, usually smaller, that you add to your home. A subpanel is basically a second panel box that gets fed off of the main panel in your home. It will feature circuit breakers just like the ones in your main panel box.

What is the Purpose of a Subpanel?

Subpanels are installed for any number of reasons, but the purpose is always the same: for more power. There are two main reasons that people install subpanels.

1. Because the main breaker box is out of space

A typical 100-amp service box has a limited amount of space for circuit breakers. Once those spaces are used up and you want to add more breakers, you have a limited number of options. You can either rewire your panel box and try to combine breakers together. Or, you can add a subpanel and significantly add more options for breakers.

2. To add power to a specific location in or around your home

Subpanels are also a great option for adding power to a workshop, garage, or barn. If you’re adding a subpanel to one of these locations, you want to be able to control it from that same location. If a circuit breaker trips in your workshop or barn, you don’t want to have to go to your basement to fix the issue.

It’s important that the subpanel is located nearby for convenience and safety. If you’re using power tools or other electronics, you should have ready access to the breaker that controls it.

What Size Wire Do I Need for Different Subpanels?

Different sized subpanels require different sizes and types of wire. Here is a table explaining the size of copper or aluminum wire that you need for different panel sizes.

Service Panel Size Copper Wire Aluminum Wire
50-amp serviceAn 8-gauge, 3 conductor wireA 6-gauge 3 conductor wire
60-amp serviceA 6-gauge 3 conductor wireA 4-gauge 3 conductor wire
100-amp serviceA 4-gauge 3 conductor wireA 2-gauge 3 conductor wire
150-amp serviceA 2-gauge 3 conductor wireA 1/0 gauge 3 conductor wire
200-amp serviceA 1-gauge 3 conductor wireA 2/0 gauge 3 conductor wire

One of the most important things to remember when installing a subpanel is to have the right sized wire. Having a wire that’s too small will not supply adequate power to your subpanel. This will result in frequently tripped breakers.

What are the Components of Your Homes Electrical System?

The full electrical system of your home consists of several different components including the main panel, subpanels, and circuit breakers. We’ve already covered the subpanel so let’s look at the other two components.

The Main Panel

The main panel in your house is similar to a control board. All of your lights, outlets, and appliances are fed off of the main panel in your home. Additionally, any subpanels that you choose to add are also fed off the main panel.

The main panel is also known as the breaker box or panel box and is often located in the basement or garage of most homes. No matter its location, the main panel is what controls everything electric in your home.

The Circuit Breakers

The circuit breakers are the individual circuits that control different parts of your home. For example, a 100-amp panel box will have individual circuit breakers for the kitchen, bathrooms, lights, and outlets.

Individual appliances such as refrigerators, air conditioners, stoves, and dryers will also often have their own circuits. Basically, circuit breakers are individual switches that allow you to control every part of your home. They allow you to turn off power to specific areas rather than having to turn off your main breaker.

Can I Have Multiple Subpanels?

If the need calls for it, you can indeed have multiple subpanels coming off of a main panel. You can even have a subpanel coming off of a subpanel if you wish.

The main thing is that you have your subpanels professionally installed so that you don’t overload your system. You also want to make sure that you don’t have insufficient power running to your subpanels.

Related Questions

How much does it cost to install a subpanel?

The cost to install a subpanel is largely dependent on who you hire to do the work. Most electricians charge an average of $80 per hour. Subpanels take anywhere from 1-2 days to install. You can expect to pay anywhere from $2,000 to $4,000 to have a subpanel installed.

How many breakers can I have on a 100-amp panel?

You usually only see around 20 or so circuits on a 100-amp panel. However, depending on the size of the circuits, you can have up to 30 or even more circuits.

Can I install a subpanel myself?

Unless you have ample electrical experience, you shouldn’t attempt to install a subpanel yourself. Working with electricity is extremely complicated and dangerous work. Only those with electrical experience are qualified to install a subpanel.

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Final Thoughts

Subpanels are a great commodity to add to a home, garage, barn, or workshop area. They’re also perfect for adding an addition or extra electronics to your home.

No matter the reason, the main thing is that your subpanel is professionally installed. This will ensure that your subpanel is installed correctly, and with safety in mind.

Upgraded Home Team
Upgraded Home Team

We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.

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