Wiring Diagram - Read and Draw Wiring Diagrams

Helps you learn about the basics of wiring diagram - what symbols to use, how to read, and how to make wiring diagrams.

What's Wiring Diagram

A wiring diagram is a type of schematic which uses abstract pictorial symbols to show all the interconnections of components in a system. Wiring diagrams are made up of two things: symbols that represent the components in the circuit, and lines that represent the connections between them. Therefore, from wiring diagrams, you know the relative location of the components and how they are connected. It's a language engineers need to learn when they work on electronics projects.

Simplest Wiring Diagram

Wiring Diagram VS. Schematics

It's easy to get confused about wiring diagrams and schematics. Wiring diagrams mainly shows the physical position of components and connections in the built circuit, but not necessarily in logic order. It emphasizes on the layout of the wires. Schematics emphasize on how circuits work logically. It reduces integrated circuits into sub-components to make the system's functional logics easier to understand . It's most useful for learning the overall operation of a system.

How to Read Wiring Diagram

Recognize Wiring Diagram Symbols

To read a wiring diagram, first you have to know what fundamental elements are included in a wiring diagram, and which pictorial symbols are used to represent them. The common elements in a wiring diagram are ground, power supply, wire and connection, output devices, switches, resistors, logic gate, lights, etc. A list of electrical symbols and descriptions can be found on the "electrical symbol" page.

Simple wiring symbols

Line Junction

A line represents a wire. Wires are used to connect the components together. All points along the wire are identical and connected. Wires on some places need to cross each other, but that does not necessarily mean that they connect. A black dot is used to indicate the injunction of two lines. Main lines are represented by L1, L2, and so on. Usually different colors are used to distinguish the wires. There should be a legend on the wiring diagram to tell you what each color means.

Contact and No Contact

Types of Connection

Usually circuits with more than two components have two basic types of connections: series and parallel. A series circuit is a circuit in which components are connected along a single path, so the current flows through one component to get to the next one. In a series circuit, voltages add up for all components connected in the circuit, and currents are the same through all components. In a parallel circuit, each device is directly connected to the power source, so each device receives the same voltage. The current in a parallel circuit flows along each parallel branch and re-combines when the branches meet again.

Series and Parallel Circuit

Tips to Draw Good-looking Wiring Diagrams

  1. A good wiring diagram needs to be technically correct and clear to read. Take care of every detail. For example, the diagram should show the correct direction of the positive and negative terminals of each component.
  2. Use the right symbols. Learn the meanings of the basic circuit symbols and choose the correct ones to use. Some of the symbols have really close look. You need to be able to tell the differences before applying them.
  3. Draw connecting wires as straight lines. Use a dot to indicate line junction, or use line jumps to indicate cross lines that are not connected.
  4. Label components such as resistors and capacitors with their values. Make sure the text placement looks clean.
  5. In general it is good to put the positive (+) supply at the top, and the negative (-) supply at the bottom, and the logical flow from left to right.
  6. Try to arrange the placement reducing wire crossings.

Start with a Wiring Diagram Software

Professional wiring diagram software can produce high quality wiring diagrams with less time. Edraw wiring diagram software is a particularly designed application automating the creation of wiring diagrams with built-in symbols. It's easy to use and compatible with Windows, Mac, and Linux platforms. With a comprehensive list of electronic symbols and components, it has been used as one of the most completed, simple and useful wiring diagram drawing program. You can get accustomed with it soon because the interface is quite familiar to MS programs. Easy to label the components, customize the colors of lines and symbols, and export the whole drawing into another format such as PDF, PNG, SVG, Visio, etc.

Wiring Diagram Software

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Wiring Diagram Symbols

Start a wiring diagram design using industry-standard symbols that everybody understand. Here are the symbols that are often used when creating wiring diagrams. The symbols below all come from Edraw. It shows partially from the built-in electrical symbol library.

Switches and Relays
Switch 1PSPSTSPDTDPSTTwo way contactSwitch 3P
Resistors and Capacitors
ResistorAlternate resistorVariable resistorPre-set resistorPotentiometer resistorPotentiometer (Trimmer) 2
Electrical Instruments
Integrated Circuit Components
IC4X Building block-top4X Building block-base1X Building blockDriverMUX 8
Transformers and Windings
Magnetic coreInductorVariable inductorMagnetic core inductorTransformerPolyphase transformer
Transmission Path
Wiremulti line bus elbowJunctionJunction crossingLeft direction flowCable group

How to Draw Wiring Diagrams

First, make sure you have a tool that you know how to use. Take Edraw for example, you need to know where to find the electrical symbols and the right way to use the symbols. Although it seems all about dragging and dropping, it's still better to learn some practical techniques to get things done quickly and smoothly. Read these useful points before starting a new design:

  1. Take a look at the Video Demo - How to Draw Circuit Diagram. It provides a step by step guide on how to use the program to draw wiring diagram.
  2. create wiring diagram
  3. Draw your wiring diagram under Engineer theme.
  4. engineer theme
  5. Find all the electrical wiring symbols in "Electrical Engineering" library.
  6. Some symbols can change more styles by clicking on the floating button on their top right side.
  7. change symbol style
  8. Connect the components with a Connector, not a Line.
  9. change symbol style
  10. Use Text button to draw new text boxes. (Note: Click the upper part of the button to draw text boxes. Use the Text Block Tool to edit existing text blocks on shapes.)
  11. Text Tool
  12. Set line jump style on "Page Layout" menu.
  13. Line Jumps
  14. To save the file as other format, click the "Export and Send" button on File menu.
  15. Export Wiring Diagram

Wiring Diagram Examples

1. Harness Wiring Diagram

This harness wiring diagram shows how to match up the wires for each connection to the wiring harnesses.

Harness Wiring Digram

2. Electrical Wiring Diagram

Create an electrical wiring diagram to display wire connections and physical layout of an electrical system or circuit.

Electrical Wiring Diagram

Read More:

Home Wiring Plan

How to Read Electrical Circuits

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