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Electrical Control Using Relay Contactors

How Relays Control Electrical Equipment – Contactors or relays are used for operating several electrical devices, including equipment such as well pumps, septic pumps, basically any type of electric motor.


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Relays and Contactors for Controlling Electrical Equipment
[ad#block] Electrical Question: In our new church building, there is a metal box mounted beside the electrical 300 amp service box labeled “CONTACTOR”. What is the purpose of a contactor ?

This electrical wiring question came from: Tim, a Homeowner from Johnstown, Ohio.
See more about Home Wiring for Ohio

Additional Comments: Great site ! Very easy. Very Clear.

Dave’s Reply:
Thanks for your electrical wiring question Tim.

How Relays Control Electrical Equipment

Tim, the word contactor in electrical terms refers to an electrical relay. Contactors or relays are used for operating several electrical devices, including equipment such as well pumps, septic pumps, basically any type of electric motor. Contactors are also used for operating lighting, such as parking lot lights. Contactors generally have a control circuit which can be operated by a manual switch or by an automatic operating device such as a photo cell, time clock, or a programmable controller. The control circuit is usually a lower voltage and a separate circuit from the equipment that is being controlled by the relay or contactor.

The Following will assist you with your electrical question:
electrical relays
electrical-relays
Electrical Relay Articles
This section will cover the use of relays that are sometimes needed to control special device loads such as Air Conditioners and other high demand equipment from starting at the same time.

You identified your project to be about Wiring Diagram, so you might find this information useful:
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Wiring Diagram
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Home electrical wiring diagrams are an important tool for completing your electrical projects. An electrical wiring diagram can be as simple as a diagram showing how to install a new switch in your hallway, or as complex as the complete electrical blueprint for your new home or home improvement project.


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Dave's Guide to Home Electrical Wiring:

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Great for any Home Wiring Project.
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Complete Guide to Home Electrical Wiring

Perfect for Homeowners, Students,
Handyman, Handy Women, and Electricians
Includes:
Wiring GFCI Outlets
Wiring Home Electric Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring Light Switches
Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
....and much more.


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Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

Electrical Tips to Help You Wire it Right

The Safest Way to Test Electrical Devices and Identify Electric Wires!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

The Quickest Way to Check for Faulty Electrical Wiring!

The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use.

Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!

The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..

The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.


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FAQs Frequently Asked Questions and Comments

2 Responses to “Electrical Control Using Relay Contactors”
  1. James says:

    I have an electrical panel with 8 breakers being used as light switches. I want to put them on 1 light switch so that all the lights are controlled together. What is the proper way to wire this to a contactor?

  2. Dave Rongey says:

    Hi James,
    Yes, one or more relays can be wired to control light fixtures. There are several ways to accomplish this. Planning the control voltage is a very important consideration.
    Dave