Despite how heavily we rely on electricity in the home, most people don’t think twice about how power gets from the power lines to the outlets we use every day. Given that home energy use accounts for about one-sixth of our national energy use, electrification of the home is a very important step in reducing greenhouse gasses and fighting climate change. That said, it’s important to remember that as electric technologies have progressed, our home power systems have not necessarily kept up. Just think about how much has changed in the past 20 years, let alone the past 100, in terms of how we live and consume energy.
As we electrify our homes further, having a basic understanding of home electricity is important to make sure we safely and effectively make the switch. So, let’s talk about the basics of home electricity: electric service and electric panels.
Let’s start with the way electricity gets into the house. Basically, your home has one big line of electricity from the power company. This is called your amp service. This represents the total volume of power that is available in your home at any given moment, which puts a hard cap on how much you can electrify. This can also be referred to as amperage. Amperage can vary a lot depending on when and how the home was built, with homes ranging from 30-amp to 400-amp service!
New constructions typically have 200-amp service, which provides plenty of power to support an electrified home. But a lot of older houses only have 100-amp service, which is quickly becoming insufficient as we rely on electricity for more parts of our lives, and especially if there’s a home EV charger involved. I myself nearly bought a house that only had 60-amp service, which was barely enough to run the lights and the appliances!
The easiest way to determine your amperage is by looking at the main breaker in the main service panel, which we’ll discuss next.
Your home has at least one electrical panel, and it may have more. These panels-- sometimes referred to as breaker boxes or circuit panels – are responsible for safely distributing electricity from the service to all parts of your home. To find your electrical panel, look for a steel box with a door on it, usually mounted on an exterior wall somewhere in your basement or utility closet. It shouldn’t be too hard to find—by law and for practical purposes, these need to be easily accessible at all times.
The most important electrical panel is called your main service panel. This is the entry point for electricity in the home. The main service panel is where you can look to see your home’s amperage.
If you open the door of this panel, you’ll see two vertical rows of toggle switches and one large switch across the top (or bottom). This large switch is your main circuit breaker, which controls the power to the whole panel. Flipping this will turn off the power to your whole home. This should have the amperage rating printed on or near the breaker, which will tell you how much power you have available in your home.
*Note that oftentimes, the numbers of the individual breakers can add up to more than your total amperage. This is because your service is how many amps can be used at one time, whereas the panel may include more that could be on at different times, or allow space for more amperage.
You may see other electrical panels that come off your main service panel. These are called sub-panels. Sub-panels are installed to create extra branch circuits when the main panel doesn’t have enough space, usually to help with an upgrade such as a new addition to the home. The power for the sub-panels still runs through the main panel, and it is still tied to your overall household service.
Within your electrical panels, you have two vertical rows of numbered switches. These are circuit breakers for your home’s branch circuits.
Branch circuits are how the power is actually distributed throughout the house. Branches start at the electrical panel and feed electricity to specific areas of the home. A well-wired house will have many different circuits for specific appliances and areas of the home. There may be one for the outlets in one part of the house, another for the refrigerator, another for the dishwasher, and so on.
Circuit breakers – the switches that you can see and interact with inside the electrical panel-- are safety mechanisms that cut off power to the circuit when there are safety issues along the circuit. These are the pieces that can “trip,” which is when something like a power overload goes wrong along the circuit and the breaker shuts off the power to the circuit. You can also use these breakers to manually shut off the power to circuits in order to do electrical work.
Visually, you’ll see that some of these circuit breakers are narrow single-width switches, and some look more like doubles. These are called single-pole breakers and double-pole breakers. The single-pole breakers provide 120 volts and are used for most of the circuits in your house, while the double-pole breakers provide 240 volts and are used for larger appliances like dryers, ranges, and air conditioners or heat pumps.
Figuring out which circuit breakers connect with which parts of the home should be pretty easy if they’re labeled correctly. There is a chart inside the circuit box with labels that correspond to each circuit breaker. Electricians who wired the house should have labeled these clearly with things like “Dishwasher” or “Second floor outlets” and so on. As you use more and more electricity in your home, it’s important to keep these circuits in mind to avoid overloading them.
If these labels inside the breaker box aren’t clear or updated, you can do some trial and error by flipping the circuit to OFF and seeing which appliances, lights, or outlets no longer have power. But if you’re consistently having problems with anything electrical in the home, it’s always safest to consult a professional electrician.
You may see some blank spaces in your panel for more circuit breakers. This means that there is space on your panel for new circuit branches. Having these spaces available is especially important if you’re adding new appliances to the home, like an induction stove, that may need a dedicated branch circuit to function properly.
As we move towards renewable, electric energy in all areas of life, many homeowners may need to update their electrical service and panels to accommodate new technologies. But even as a renter, knowing how power works in the home can help you get the best use out of your appliances and give you an understanding of how to safely use electronics within your existing home. Spend some time getting to know your electric service and panels so you’re ready when you start to electrify!