You may or may not have heard the terms line and load when working with electrical connections, but what do those terms mean? Does line mean straight and narrow? Does load mean a heavy heap of something a truck hauls? Well not exactly. In the electrical world, these electrical terms are the difference between a device working properly or not.
Line and load refer to the power connections coming into or out of electrical devices in the scheme of your electrical system.
You see, the incoming feed from the utility company comes into the line side of an electric meter. It leaves the meter from the load side and then feeds the line side of a disconnect or electrical panel.
In the case of the disconnect, used to interrupt the power after the electric meter, the power comes in on the line side and out on the load side. The power is then fed to the home's electrical panel. The electrical panel also has a line and load connections. The line feeds the main breaker in a circuit breaker panel or a set of cartridge fuses in a fuse panel.
In a breaker panel, branch circuit breaker's supply the load feeds to switches, outlets, and appliances throughout the home. As you can see with the flow of power, there is an in and out of every device, thus a line and load connection point. The correct connections on the electrical devices make a difference but none more important than that of the GFCI receptacles.
Ground fault circuit interrupters (GFCI's) implement line and load connections and employ an automatic trip feature when a difference of potential is detected. The back of these outlets are marked and they usually come from the factory with a piece of tape covering the load connection points. This taped portion is a great way of knowing which is the load, that and the markings on the plastic casing.
Line and load connections are not limited to only these connections, but by now you have a better understanding of the terms. For electrical safety reasons, it is wise to always use the line connection to attach the incoming feeder wires. In the case of adding outlets downstream of the GfCI receptacle, these are fed from the load side of the GFCI receptacle. To make this connection, first turn off the power if the device is already live, then remove the tape covering the load side of the receptacle. Under the tape, you will find the connection point.
Just remember that the load is the power used by the devices attached to branch circuit breakers of the electrical system.The load is always going to feed something like an outlet, switch, or appliance. In simple terms, it is the line in and loads out. It is just that simple to understand and remember.
Another thing to consider when making these connections is where the wires attach and the color of the wires that attach to the appropriate connection. Line connections have wires attached to them in colors like black, red, and blue. These are considered the hot wires and carry the current to the devices. White wires are used for neutral connections, while green or bare copper wires are used for ground wires.
The load connections follow these same principles. Hopefully, that explains the differences between line and load connections and clears up their intended uses.