What Do Line and Load Mean in Wiring? | Hunker What Do Line and Load Mean in Wiring? By Chris Deziel. SAVE; When referring to an electric device that can be connected to another one, such as a receptacle, line refers to the wires feeding it from the panel, which is upstream from the device in terms of the flow of electricity. On the Wiring diagram - Wikipedia A wiring diagram is a simplified conventional pictorial representation of an electrical circuit. It shows the components of the circuit as simplified shapes, and the power and signal connections between the devices. A wiring diagram usually gives information about the relative position and arrangement of devices and terminals on the devices, to help in building or servicing the device.