Highlights
A breaker box helps to control the flow of electricity in your home.
The three main wires inside a breaker panel are black, white, and green.
The green wires are the ground wires, which prevent electrocution.
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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?
Photo: Marvin Samuel Tolentino Pineda / iStock / Getty Images Plus / Getty Images
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.
FAQs
Which wire is ground and neutral? ›
The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel. The green wire (or it can sometimes be uncolored) wire is the "ground" wire, it will take electricity back to the breaker panel, then outside to a rod that's buried in the ground.
Where do all the neutral and ground wires go in the panel? ›Neutral wires are usually connected at a neutral bus within panelboards or switchboards, and are "bonded" to earth ground at either the electrical service entrance, or at transformers within the system.
What is the neutral and ground on a breaker box? ›Neutral is the return path of the current, and ground wire holds the fault current to trip the breaker in protecting the person and the facility. The neutral and ground should never be bonded together in the facility except for the main panel.
Which side of breaker box is ground? ›The white wires (neutrals) are on the right bar, while the bare copper wires (grounds) are connected on the left bar. At the top of the panel, the two bars are joined together by a single bar, the subpanel neutral, and also a green screw (see top left) that grounds the panel too.
Which color wire is always connected to ground? ›Green is the most common ground wire color, but green wires with yellow stripes and bare copper wires (with no colored insulation) are also ground wires. Ground wires are conductors, like shock absorbers, whose purpose is to give electricity a safe place to go—into the ground below your home.
Can neutrals and grounds be on the same bar in main panel? ›That is now correct even in the NEC or The National Electrical Code. In every panel, there should always be a separate ground bar. Only neutral wires must be in the neutral Bar and ground wires in the ground Bar. As a result, wires should never be bundled together in a panel.
What happens if you mix up ground and neutral wires? ›Once you connect the neutral to the ground, you could shock yourself or others upon touching the metal case. This is because the metal case is connected to the ground. So, if the neutral or live wire is connected to the ground, the ground will become a live wire and create a dangerous situation.
Can you put 2 neutral wires together in a breaker box? ›UL 67 is very specific when it comes to neutral wire terminations in the electric panel. The standard states, “An individual terminal shall be provided for the connection of each branch-circuit neutral conductor.” Therefore, any panel bearing the “UL 67 Listed” sticker should not have double tapped neutrals.
Why are neutral and ground separate? ›So, why do you separate the ground and neutral in a subpanel? Because when we bond them together, it gives your neutral wire (the one carrying electrical currents BACK to the source) multiple pathways. That's how the chassis of some equipment will become energized.
Does neutral wire go to ground? ›Neutral wire carries the circuit back to the original power source. More specifically, neutral wire brings the circuit to a ground or busbar usually connected at the electrical panel. This gives currents circulation through your electrical system, which allows electricity to be fully utilized.
Does ground wire go to box or receptacle? ›
How to Ground Wires in Metal Boxes. In a system with metal boxes, the pigtail method is considered the most secure. In this arrangement, both the receptacle and metal box are grounded. Ground wires are spliced together and attached with a pigtail to the box and receptacle.
How do you tell which wire is hot when both are black? ›The easiest way to tell which black wire is hot is by using a circuit tester. If you don't have a circuit tester, you can also use a multimeter to test for continuity. Simply touch one lead of the multimeter to each of the black wires in turn and see which one gives you a reading on the multimeter.
Can neutrals and grounds be on the same bar? ›This is something that a lot of electricians get wrong. That is now correct even in the NEC or The National Electrical Code. In every panel, there should always be a separate ground bar. Only neutral wires must be in the neutral Bar and ground wires in the ground Bar.
Are the ground wire and neutral wire basically the same? ›The key distinction is that ground wires are only carrying current in case something goes wrong. They're a failsafe, essentially, directing current away from the plugged-in or lighting device if a problem occurs, such a short. The neutral wire completes the circuit and allows electricity to flow.
What color are the hot neutral and ground wires? ›US AC power circuit wiring color codes
The protective ground is green or green with yellow stripe. The neutral is white, the hot (live or active) single phase wires are black , and red in the case of a second active. Three-phase lines are red, black, and blue.