Relay Circuits
Home Assignments Assignments Checklist


Relay Circuits - Relay Logic - Online Basic Course

This information provided by

Control of electrical equipment is essential for proper function. A relay circuit is designed to control operation of electrical equipment. Many types of relays have been developed for a variety of applications.

This set of ten different Relay Circuit Assignments is intended to present a learning opportunity online for anyone who seeks a better understanding of relay circuits. These relay circuits range from simple two wire control to forward/reverse operations of motors with jog capability. Performing the assignment tasks will strengthen technical vocabulary, will give several hands-on experiences with these circuits, and will contribute to a knowledge base of relay circuits which every working electrician should possess.

Each assignment presents appropriate vocabulary, background text, ladder diagrams, audio lectures, pictures, and questions with answers about the relay circuit. The emphasis of the assignments is the translation from a description of function to a ladder diagram and then to actual wiring of the circuit under study. Hands-on activities form an essential portion of this educational activity. To participate fully, there are some electrical materials which will be needed. A list with suggested sources is provided near the bottom of this page.

Upon successful completion of each assignment, your understanding of relay circuits will increase. The intent of these basic relay circuit studies is to build a foundation upon which to understand advanced concepts.

Admittedly many applications learned here in these activities are not in current use due to the implementation of more sophisticated control techniques. But all advanced applications have their basis in the relay circuits which will be presented here. 

These exercises about relay circuits are intended to provide educational experiences only to working electricians.  These exercises are not for a person who is not a working electrician. If you are not a working electrician, contact your local educational institutions to see what might be available to you to aid in your acquiring electrical knowledge.

This online course in basic relay circuits is presented by Although the course can be used without charge, you may feel compelled to support the web site with a  payment if you have learned from the material presented here. The level of paid participation will determine if more courses will be added and if this one will be continued.

A $25 fee is requested to help pay the bandwidth charges, authorship, memory cost, and web development fees. Of course, you don't have to pay when you are done with the assignments. You can just go on your merry way. But, upon completion, if you feel this activity has helped you to be a better electrician, then send on your payment. Invest In Yourself.  Details about payment for this course at the end of Assignment #10. Click HERE to see the form for sending payment.

If you pay $45 for the course in advance of use, you are entitled to email support from the instructor  for questions you may develop as you proceed. Click HERE for payment instructions. 

When you have finished all ten assignments successfully, make your payment. A certificate of completion will be sent to you. See a sample certificate HERE. No certificate of completion is available without payment of a course fee.

Previous Experience
As a  working electrician with any time on the job and some completed educational activities, you probably know some or even all of the material presented here. As you look over the assignments you may be confident of your ability to wire and draw some of the diagrams from memory. You may also be able to answer most questions without difficulty. Great. In this case just skip over the assignments you fully understand.

Here is a caution about skipping the actual wiring and sketching aspects. Don't. Reading diagrams, drawing diagrams from memory, and wiring relay circuits from memory are essential skills all successful electricians must possess. This background will aid in troubleshooting when problems develop. Further this foundation will make more advanced applications easier to understand with a firm foundation.

Electrical Theory
Depending on how long it has been since you studied electrical theory, you may want to review. Click HERE to go to an online collection of electrical theory facts which may be of use to you.

Obviously there is more information presented at that you will need for this online course. But you may want to expand yo0ur knowledge of electrical theory. Set the main page as a favorite you you can easily return from time to time as the need arises.

Group Study
You may even want to get your electrician buddies together to work on these assignments. Since getting all the material together to do the wiring will take some time, having more than one person work on it at the same time will be efficient. And even fun! Working together with another electrician will produce a better educational experience. Why not learn together from the material and from each other. Everyone has had different work experiences. Working together allows you to benefit from that accumulated experience. You will strengthen your understanding of any topic when you explain it to someone else.

Materials Needed
The electrical components needed are available from many different sources. I have included places where I know these parts can be found. By including a specific source, I do not feel this is where you need to get what you will use for these exercises. This is America after all. Go on to get what you need where ever you can find what you need. A junk box in the van, shop, or warehouse may have much of what you will need. Flea markets and eBay are even worth checking out. Nothing has to be new to be useful for these exercises.

You may click on the name of each item to see a picture of what I use in my classes for each part when I instruct this topic in a classroom setting.






Normally Closed Push Buttons (mounted) momentary contact

any N.C. pushbuttons will do

Radio Shack Part


Normally Open Push Buttons (mounted) momentary contact

any N.O. pushbuttons will do

Radio Shack Part


dpdt control relays 120 volt coil

power relay

WW Grainger


spdt selector switch (mounted)

any three way switch will do

Any electrical supply house


spst on/off switches (mounted)

any single pole switch will do

Any electrical supply house


Edison Base lampholders (mounted)

any keyless lampholder will do

Any electrical supply house


Light Bulbs ( red, green)

any colors will do

Any electrical supply house


Power Cord with on/off switch (mounted)

any cord will do

Any electrical supply house


Test Leads with alligator clips (various colors)

these are better than trying to hardwire

Radio Shack Part


Time Clock with 120 volt motor SPST OK

any one will do

Any electrical supply house


Photo Cell 120 volt

any one will do

Any electrical supply house

Tools Needed
Pencil and paper for notes
three ring notebook
filler paper
paper punch
volt detect tester
voltage tester for 120 volts
continuity tester
screw driver
wire strippers
Safety Glasses
120 volt power source GFCI protected

Free Literature
Manufacturers of electrical components used in relay circuits produce quite a bit of free literature to be used by their customers. Follow the links for Allen Bradley, Cutler Hammer, Square D which are given at the bottom of this page in the link rack. Take a look to see what they might have that will help you obtain education for application of their products.

Always of concern to an electrician is electrical safety. Please review the safety information provided at Click HERE to go to a collection of details which you can use as you prepare for the assignments in this online course.

Of Special Note
Use a GFCI protected circuit for these exercises. Do not energize your test circuits until you are sure of the connections. Have another working electrician verify that you have done the work correctly before applying power to the test. Then stay well clear of the uninsulated aspects of the circuit while power is on. Remember to turn off power before making adjustments to the wiring. Click HERE to read about GFCI protection.

This method of providing educational activities in the open on the internet without passwords seems like a grand experiment to me. You can proceed at your own pace. You can work on the assignments in your own time. You can work from home. Or from the library. Or from the office.  And you can embrace subject mastery as your goal. No one will be pushing you toward completion. Take your time to fully understand each relay circuit given here. If, upon completion, you feel you have gained useful information, then and only then are you encouraged to pay the course fee. Let's see what happens.

Text Links
As you move through this learning activity you will encounter text link ads from time to time. If you see a topic given which is interesting to you, click on the link. See what's there. Then use your back button to return to the assignment. Here is a sample.



Follow these Google text ads to serve your specific needs as you may determine.


The internet provides all users with a huge array of sources of information. By clicking on links, you have the chance to find details which will expand your mind. The serendipity aspect of internet use is wonderful. Click On!

Suggestions For Improvement
As you work through this online course, please email suggestions to make the course better. The internet allows everyone to join a community. Participate by suggesting  improvements where you can.

Have fun! Cheers:>)

David U. Larson

Diagram Types
Here is a list of the ten different types of relay circuits which are included in this online course. Click on each to see what is included in this online course.
Job #1 Two Wire Control
Job #2 Lighting Control
Job #3 Three Wire Control
Job #4 Independent Operation - Multiple Buttons
Job #5 Dependent Operation - Multiple Buttons
Job #6 Sequence Control M1 then M2 then M3
Job #7 Or Operation M1 or M2 or M3
Job #8 Forward Reverse Motor Control
Job #9 Jog Run Operation with Control Relay 
Job #10 Forward Reverse Motor Control with Jog



If you would like to research any of these topics further, enter the search term in this Google Search Box:



Begin HERE - Click HERE to go to Job #1

Quick Links Directory
Diagrams        Questions        Answers


Use these Relay Circuit links to go to where you left off in your online activities.
Job #1
Job #2
Job #3
Job #4
Job #5
Job #6
Job #7
Job #8
Job #9
Job #10
Allen Bradley
Cutler Hammer
Square D

 Here are links to where these 2008 NEC items can be purchased. You may find good prices from some sellers there.


Use this Google search box to find topics on this website: 

The next Master Electrician Course in Port St. Lucie begins January 9th, 2010. Details HERE.
Products For Sale  
  1998-2010 by David Ullian Larson
Advertise at
Link Exchange Solicited For Appropriate Products 
Companion websites include: (not yet)

Other websites which may be of interest: