• SkillCat Team

Types of Diagrams

Updated: Jun 16

Wiring Diagrams: Chapter 1


In this module, we will give you an overview of wiring diagrams. We will cover:

- What a wiring diagram is, - Parts of a wiring diagram, and - Types of wiring diagrams. Skip to quiz!


Wiring Diagrams


An electrical wiring diagram is a blueprint of the electrical components within a system. Wiring diagrams can tell you:

  • The components in a circuit,

  • The wiring of a circuit, and

  • How a circuit works

Wiring diagrams can be considered the map of an electrical system. As map of the United States can show you the name and place of each state, similarly a wiring diagram can show you the name and place of each component in an electrical system.

Correctly reading electrical wiring diagrams is critical to installing, maintaining, and troubleshooting electrical circuits. Without a wiring diagram, it is very difficult to understand a circuit.


There are three parts to all wiring diagrams:

  • The diagram,

  • The legend, and

  • The notes

We will explain more about each part in the coming slides.


The diagram displays the components of the circuit. Each symbol on the diagram represents a component within the circuit. The lines running between each symbol represent a wire. You can see an example of a diagram in the picture to the right.


The legend helps you understand the diagram. The legend explains what certain symbols on the diagram represent. The legend does not explain every symbol on the diagram. For example, the legend will tell you that CONT stands for contactor.


The notes section on a diagram displays important information about the circuit. The information found in notes will vary depending on the diagram. For example, the notes section can tell you that a component on the diagram may not be present in the circuit.


There are two common types of wiring diagrams. They are:

  • Schematic diagrams, and

  • Ladder diagrams

We will cover each type of wiring diagram in later modules.


Each type of wiring diagram has unique advantages and disadvantages. For example, a schematic diagram displays the wiring between components, but a ladder diagram will not. If you are wiring, a schematic diagram will be much more useful.


A wiring diagram is a blueprint that can show:

  • The electrical components in a circuit,

  • The wiring of components, and

  • The flow of current within a circuit.

There are two types of ladder diagrams:

  • Schematic diagrams, and

  • Ladder diagrams

Each diagram has unique advantages and disadvantages.



Question #1: A wiring diagram can show:

  1. The components in a circuit

  2. The wiring of components

  3. Important notes about the circuit

  4. All of the above

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Answer: All of the above

A wiring diagram can display the components in a circuit, the wiring of components, and important notes about the circuit.


Question #2: Each type of wiring diagram has unique strengths and weaknesses.

  1. True

  2. False

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Answer: True

Each type of wiring diagram has unique advantages. For example, a schematic diagram is great for looking at wiring.


Question #3: The legend on a wiring diagram displays:

  1. Notes about the circuit

  2. The dimensions of the blueprint

  3. What certain symbols on the diagram represent

  4. The amount of voltage in a circuit

Scroll down for the answer...











Answer: What certain symbols on the diagram represent

The legend displays what some symbols represent on a schematic diagram. For example, a legend may say the SR stands for start relay.


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