Electrical wires are wrapped in colored insulating casings to indicate each wire’s purpose.
Green, green with yellow stripe, or bare copper are ground wires.
Black wires are hot wires that run to the electrical outlet from the switch.
Red wires are hot wires common in a 240-volt outlet or when a wall switch controls the outlet.
Blue and yellow wires are hot wires for ceiling fans and three- or four-way switches.
White or gray electrical wires are neutral wires.
All home electrical wires made in the U.S. follow standard color codes—NFPA 70, National Electrical Code (NEC)—set up by the National National Fire Protection Association. Each color identifies a wire’s function in a circuit. Before you try to repair a faulty switch, change an overhead light fixture, or splice wires, learn about the colorful—and incredibly important—world of electrical wiring.
It’s important to note before we begin that working with any type of electrical wiring is typically best left to a professional and can be very dangerous. Proceed with caution.
Why Are Electrical Wires Colored?
If you’ve ever witnessed your lights flicker or have lost your electricity because of a power surge, you might have run to your electrical panel to check out what’s wrong. When you opened the panel, you likely saw a variety of tangled colored wires. If you’ve ever wondered why they’re colored that way, well, there’s a good reason for it.
Electrical wires are wrapped in colored insulating casings to indicate each wire’s purpose. Today, every electrical and electronic device made uses color-coding to quickly and unmistakably identify each wire:
Hot or live circuits can be colored black or red, but sometimes blue and yellow.
A neutral wire might be either white or gray.
The ground wire might be green, green with a yellow stripe, or a bare copper wire.
Because these colors can vary, learning the ropes can be a bit confusing at first. However, knowing what the colors mean and why they are important might help you during a blackout or when it’s time to check installing a new light fixture off your to-do list. But remember, most electrical wires carry high voltage that can harm you if you’re not careful, and you must treat all colors with caution.
What Are the Different Electrical Wire Colors?
If you’ve ever felt a little jolt when accidentally coming in contact with an exposed wire or trying to repair a switch, you know how dangerous electrical wiring can be. Thankfully, the different electrical wire coatings around the copper conductor wires can help you identify all the clues you might need to determine whether the wire is a ground, hot, or neutral.
Green, Green with Yellow Stripe, or Bare Copper: Ground Wires
Green is the most commonground 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.
A ground wire helps the positive charges in your home’s outlets and electrical panels get to the ground in a direct, controlled, and safe way, where they can release without the risk of fire or an electrical shock. In other words, these wires reduce the risk of an electrical overload by redirecting excessive electricity during a surge from things like a short circuit or lightning strike.
Chances are, if you have a newer home built after 1960, you have a properly grounded system. However, if your home was built before 1960, there’s a safe and easy way to make sure your electrical system is grounded. Just take a look at your outlets.
Grounded outlets have two slots and a D-shaped slot. These are connected to a ground wire.
Outlets with only two slots but missing the D-shaped slot may not be connected to a ground wire.
Still not sure? Don’t risk the chance of getting shocked and instead reach out to a local electrician.
Black: Hot Wire
You may have built simple circuits in science class using a battery and a light bulb, with electrical current traveling from the battery (the source) to the bulb, then back to the source.
The wire that carried the electricity was the hot or live wire.
In your household’s wiring, this wire is typically black, but it may also be red (more on that in a second). Black wires are always hot wires that carry electricity. You should always treat these with extreme care. They feed a switch or outlet and are also sometimes used as switch legs or the connection that runs to the electrical outlet from the switch.
Red: Hot Wire
You will usually only see a red wire when an outlet is a 240-volt outlet or when a wall switch controls the outlet. In this case, when the switch is "on," the red wire will supply power to the outlet instead of the black wire. Like black electrical wires, red wires are also hot or live wires.
Red can also be the connecting wire between two smoke detectors that are hardwired. Also, if your circuit box is wired for 240 volts instead of 120 volts, you may even see both red and black wires.
“Another common location where you can see a red wire is a 3-way switch,” says Tyler Keezer, home energy specialist at Switch Electric. “This is when you have two switches in a home that control the same light. The red wire is used as a second path to send electricity down from one switch to the other. When you’re working on these switches, you need to use caution because the red wire can also have voltage on it depending on what position the 3-way switches are currently in.”
Blue and Yellow: Hot Wires
It’s uncommon to see blue and yellow wires in a typical outlet. While these wires are live wires and carry power, you might only see yellow wires as switch legs to ceiling fans or outlets controlled by light switches.
You may also see blue wires used in three- or four-way switches. For example, if you have a light switch at the bottom and top of a staircase that controls the same light fixture. This is very uncommon though, and typically you will see a red wire in this type of configuration as mentioned earlier. You may have seen blue wires if you’ve ever wired a three-way switch or a four-way switch.
White or Gray: Neutral Wires
White or gray electrical wires are neutral wires; white wire is more common than grey in most households.
The purpose of a neutral wire is to provide a return path for electricity in a circuit, and typically connects at the main electrical panel to a single conductive piece of metalknown as a neutral bus bar. Although they are called neutral wires, they can still carry electrical current, so as always, it's best to treat these wires cautiously.
Fixing electrical problems is not as simple as changing a light bulb. In fact, the U.S. Fire Administration lists electrical malfunction as one of the top causes of house fires. Wires are color-coded for a reason, so before you start tinkering with an outlet or installing a new appliance in your home, make sure you understand the differences and treat all of them with extreme caution.