Control Wiring - 2 Wire Control - ON/OFF Circuit

Two wire control is usually used for a simple ON/OFF device such as a toggle switch, float switch, thermostat, or other device that would switch off of a high/low limit.  

It is one of the most basic and common circuits which is even used for household 2 way light circuits yet it is often misunderstood.  All circuits must make a complete loop from the power supply, through the switch, then through the load, then back to the power supply.

In this video we show you how to wire a 2 wire control circuit to a relay and a light.

See image below for an example of 2 wire control being used to pull in a contactor to start a 3 phase motor.  When the 24VDC relay energizes, it pulls in the R1 contactor that feeds three phase power to the motor.



Next Steps

Go to the Control and Power Wiring Lesson series to select your next lesson.  There are also many other Lesson Series on PLC Programming and Industrial Automation.