When the cable has only two conductors, as most 120-volt cables do, the white wire is always neutral, and the hot wire is always black. In most circumstances, the ground wire is kept bare, however in certain cases, the ground wire is colored green. The additional wire in a three-conductor cable is red, and it is nearly usually employed as a hot wire. However, if it is desired to use this third conductor as neutral, it can be stripped off at both ends and attached to another terminal.
In some installations, it is necessary to distinguish between red and black wires because they are used for different things. For example, in a building with old wiring that contains many red and black wires running together, it is important to identify which ones are hot vs. which ones are neutral. When installing a new cable or replacing old one, any color code on the cable should match the colors on the wall plate or nearby junction box. If there's a discrepancy, you may have an electrical hazard waiting to happen.
The term "red" when used to describe an electrical connection means that this is the positive side of the circuit. The black wire is the negative side. It is important to remember this terminology since it will help you avoid any confusion when working with your household electricity.
Red and black wires are equivalent in terms of how much current they can carry. But because brown and white are often also used as neutral wires, care must be taken not to mix up the neutrals with the live wires.
The neutral wire is often confused with the ground cable due to a number of factors: Cables of various colors: The color used for hot wires in a typical, relatively new house is white, which is also the color used for neutral wires. Older houses may use black or red instead. Always remember that black and red are different colors. Grounding circuits: Neutral and ground cables usually connect to different parts of the electrical system- although they can be the same cable if you're working with a panel made before 1989- so it's important that they not share a circuit. A shared circuit can cause problems such as electricity leaking into other parts of the house and burning people. Power lines: The term "ground" comes from the fact that this cable runs along the ground near your house foundation. It's purpose is to provide an alternative path for current to flow in case any nearby power lines get damaged. This might happen when someone drives a truck across a power line or falls onto a power line while digging. Circuits: On older panels, each room of the house had its own breaker. If you were only using one floor of the house at a time, then there would be a white neutral wire running to all the rooms on that floor and a green ground wire running to the common ground rod located by the basement door or somewhere else outside the house.
The 12-3 cable is a four-wire, 12-gauge cable. There is one black conductor, one white conductor, and one red conductor. And one is unadorned (no insulation). Except for a switch loop, the black and red wires are hot, while the white wire is neutral. The 4 wires in a 2-wire circuit are also called "legs" or "poles". A 3-wire circuit has a third insulated leg for another device. This is most often used as a ground.
Black = power/hot White = neutral Red = ground
Switch boxes and outlets should all be compatible with 12-3 wiring. If you're not sure which type of wiring your house is set up for, contact an electrician before you start working on any circuits.
12-3 wiring is common in houses built before 1990. If you're lucky enough to still have all 4 wires inside your walls, you can keep them that way by not using any metal objects as curtain weights or sheets. Metal conducts electricity!
If you need to replace your old wiring with new wiring of the same size, always use the proper gauge of wire for the job. In this case, that's 12-3 wire. It can be hard to find but it's available at most home improvement stores.