Wire relays come in a variety of configurations, but their diagrams, known as ladder or relay logic diagrams, depict the relay device, wire connections and switches. The position and timing of the switches are also noted in the diagram.
A simple relay logic diagram is shaped like a rectangle, and as more relays are added to the diagram, it begins to resemble a ladder. A basic diagram for a 110/120 volt household circuit has two wires that are labeled L1 and L2. L1, which is controlled by the relay switch, is the hot wire, and L2 is the neutral one.
L1 and L2 originate at the top of the diagram and are represented by two short, parallel, vertical lines. A downward-pointing arrow between the two wires represents the ground. Both wires then extend outwards toward the sides to create the top part of the rectangle shape.
The wires turn downward again, and at the halfway point, they head towards the center of the rectangle. On its path toward the center, L1 reaches a stop switch before terminating at the start switch in the center. L2 passes through a relay coil before terminating at the center. A third and fourth wire bisect L1 and L2 after the stop and coil but before the start switch. These shorter wires terminate at another relay coil.
At the bottom of the rectangle, L1 leads to a third relay coil, and L2 connects with the electric device, which leads to the third relay coil and completes the circuit.