Types of diagrams

Position diagram

The position diagram shows the location of all components and is most often not included by the manufacturer.

Schematic Diagram

Schematic diagrams are also known as ladder diagrams and are helpful when you need to see the electrical current flow. Schematics will not show the physical location of any equipment in the circuit. Schematic diagrams move from left to right. The left side is the hot or line side. Switches and loads are in the middle. Neutral or common is on the right side.

Frequently a piece of equipment will contain more than one voltage passing through it, such as a relay. The relay has 24V going to the coil, but the switching contacts (NO and NC) will have 120V. In this case, the 24V coil would be in the lower level of the schematic, and the contacts will be in the top section of the schematic. In this case, the components are labeled so the technician can identify the switching contacts the coil is powering. An example would be a relay coil labeled RC1 and the contacts labeled RC1.

Wiring Diagram

Wiring diagrams are the most useful diagrams as they show actual wiring connections between each piece of equipment throughout the circuit. These types of diagrams are beneficial if you need to rewire a circuit or trace out wires since you can see the physical location of wires. Wires run horizontal and vertical in the wiring diagram.

Some manufacturers will represent two or more wires joining with a dot at the connection point of the wires. The connection point can be useful when there are many wires to trace.

Sometimes you will see a half circle representing a wire crossing over another wire to make it clear there’s no connection made and the wire has jumped over.

Wiring diagrams place components within their general location in most cases and also use symbols that represent their likeness.

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