If you’re working with electric wire, you need to understand what the color codes for different wiring mean. Not knowing this can lead to making the wrong connections, which can prove dangerous. It’s not complex to learn, and the information is vital to keep close by whenever you’re working on your home wiring. Wires each provide a different function and the color code will tell you what that function is. Be aware, however, that sometimes exceptions do exist.
The main thing you need to remember is that the black wire is the hot electric wire. It’s the one that is live and carrying the current, so when you work directly with one of these, always cut the power and use a tester to be sure there is no current to the wire before handling. You should also never, under any circumstances, try to use a black wire as a neutral or a ground wire. Black wires will feed an outlet or a switch, and you often use them as switch legs.
You’ll find that red wires are often the second hot electric wire when you’re making a 220-volt installation. They’re also used for the hot wire in 100-volt installations and in switch legs. Red wires can also be the interconnecting electric wire for two hardwired smoke detectors.
Green or Bare Wires
Green or bare copper electric wire will always be the ground wire. You will use them to give a safe grounding for electrical devices, and in junction boxes they’re always grounded to the box itself. Failure to properly ground an electrical connection can result in the device shorting out and causing a fire. Switches will have also grounding screws, as will all electrical appliances.
Blue and Yellow Wires
Although you won’t see blue and yellow wires with electrical devices, you still need to know about them. They’re used as hot wires and are usually pulled in conduit. You’ll find blue wires being used as travelers in different switch applications, usually on three-way or four-way switches. They can also be used as switch legs and in this scenario, you’ll usually find them in fans or lights.
By contrast, yellow wires are almost invariably only used as switch legs and can be found in switched outlets, fans, or lights.
The white electric wire will always be neutral when working with 110-volts. It’s possible that gray can be used as an alternative, but in the vast majority of instances, the wire you see will be white. Connect this without worry to the neutral terminal in an outlet or junction box.
There are a few exceptions to the normal color codes in wires. For instance, when you’re working with 240 volts and you have a two-conductor cable, the white wire can be the second hot wire instead of the neutral. It can also be used as a switch leg or if you have a three-way switch. In a case like this, you will need to mark the white wire somehow to show it’s not being used as a neutral connection.