Electrical Schematic Symbols

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

After completing this lesson, you will be able to explain why electrical schematic diagrams are important, and recognize some of the most important symbols used in those diagrams. A short quiz will follow.

What is an Electrical Schematic Diagram?

One day you get a job working as an electrician. You're asked to build a circuit, but your boss likes to talk super-fast. He says something like:

Connect the breaker in six parallel branches: three of them containing two outlets and six lights, two of them four outlets and two lights, and one of them as a separate line that connects to one of the outlets in the 4-2 branch. And make it fast!

Circuit Diagrams Can Get Very Complex
Circuit Diagrams Can Get Very Complex

Unless you're very quick, this might not work so well. If your boss really knows what he's doing, he'll instead give you a diagram. But not just any diagram: an electrical schematic diagram.

An electrical schematic diagram, or more simply circuit diagram, is a drawing that shows the connections and components in an electrical circuit. It doesn't represent how they're arranged, just how they're connected. There's nothing to show which wire goes through which wall, or how the wires are positioned -- that would be a whole separate diagram. A circuit diagram is arranged to make it as clear as possible how to connect everything.

Using Symbols

But reading electrical schematic diagrams isn't always easy. For one thing, they can be super complicated in real-life circuits. But for another, you kind of need to know another language: a language of symbols.

Every component in a circuit diagram has its own symbol to represent it. After all, we're not all talented artists. If you have to carefully sketch a light bulb every time you put one in a circuit, the diagram probably won't look that good. And perhaps more importantly, it will take much more time to draw. Using simple symbols makes drawing circuit diagrams much quicker and easier.

Examples of Common Symbols

There are more possible symbols for circuit diagrams than we could possibly talk about in a single lesson. So let's just look at some of the most important ones to know.

The Many Circuit Symbols People Use
The Many Circuit Symbols People Use

Any straight line in a circuit diagram represents a wire. And various things can be connected to those wires. One is a battery, which looks like this:


Every circuit needs a power source, such as a battery, or nothing will work. It provides the energy to make the other components in the circuit work. The power source for your house is the electric company in your city or town. A bulb is another common symbol, and looks like this:


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