Breaker Box Wiring: Which Wires Are Neutral and Ground?

A breaker box is like the mitochondria—it’s the powerhouse of your home. This electrical panel divides power across your home and ensures that you don't overload your circuits, which can lead to a fire. For many, the wiring in that box is nothing but a mystery behind a metal door, but it’s a good idea to have a basic idea of what’s going on in there, especially if you need to locate the breaker box’s neutral or ground wiring. 

What Is a Breaker Box?

An electrical circuit breaker panel, or breaker box, is the main hub for all the electrical outlets in your home. It’s usually located in a basement, garage, or utility room—somewhere out of sight, as it’s not a particularly handsome home feature, identified by its flat metal panel and dull coloring.

The breaker panel can hold as much as 400 amps of total power, which gets divided up into circuits represented by individual switches that correspond to areas of your home, like the kitchen and laundry room. 

The breaker box serves an important safety function: It shuts off power to branch circuits whenever an overload is detected. You’ve probably experienced the power going off when you’ve run too many appliances at once—while momentarily annoying, this is the breaker box doing its job to prevent the circuit wiring from overheating and potentially causing a fire. 

What Is Inside of a Breaker Box?

If you aren’t familiar with the features of a breaker box, here’s what you should know. 

Main Switch

The large switch at the top of the panel controls all the power, so when it’s off, all the electricity to your home will be shut off until you flip it back on.

Circuit Breakers

Your circuit breakers, usually set in two rows of switches and (hopefully) clearly labeled, control the different circuits in your home. Some of the breakers are single-pole switches with an amperage of 15 or 20 amps, common for circuits of 120 volts. Double-pole switches can handle 240 volts and typically connect to high-powered items like air conditioners and EV charging stations.

Lugs and Wires

If you remove the front panel of the breaker box, you will reveal all the lugs and wires that are connected to the circuit switches. You will encounter three wires: black, white, and green (or plain copper).

Electrical Wiring

It’s important to know how to identify the different kinds of wires used so you don’t make any dangerous mistakes when checking out your breaker box. Unless you’re a qualified professional, you’ll want to hire a local electrician to conduct any major electrical work safely. 

• Black: The hot wire, responsible for carrying electricity from the breaker panel to the light or switch. 

• White: The neutral wire, responsible for sending unused electricity back into the breaker panel.

• Green: The ground wire, responsible for taking electricity back into the breaker panel and then into a rod buried in the ground—this prevents electrocution. Sometimes the green wire is not colored at all and is just identified by bare copper. 

What Is a Short Circuit?

A short circuit involves a misdirected flow of electricity. This occurs when a hot wire (black) touches a neutral wire (white) and overloads the current within the circuit, creating heat. A short circuit should trip your breaker, which breaks the irregular circuit—hence the name—with the intention of preventing a possible fire. 

What Is a Ground Fault?

Similar to a short circuit, a ground fault is when electricity takes an unexpected journey and is directed into the ground. This occurs when a hot wire (black) touches a ground wire (green or copper) or any grounded part of the system, like the metal box itself. Your circuit breaker will detect the sudden surge of electricity, causing it to trip. Ground faults can be dangerous, especially in areas with high moisture. That’s why many bathrooms and kitchens have ground fault circuit interrupters (GFCI) that cut power if they detect a ground fault to prevent you from getting an electric shock.