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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.


Relays and Contactors for Controlling Electrical Equipment
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.

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Wiring Diagram
Wiring Diagram
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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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?

    • 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