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Electrical Wire and Cable

120 and 240 Volt Motor Wiring

Should I wire my motor for 240volt or 120volt? The advantages of wiring a volt motor for 240 volts.

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Using a Circuit Breaker Interlock Kit
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How to Wire a 120/240 Motor for 240 Volts
Electrical Question: Should I wire my motor for 240volt or 120volt?

When wiring a 120/240volt motor is there any significant difference in power consumption 120volt vs 240volt, and any lose or gain in motor longevity?

This electrical question came from: Bruce , a Homeowner in California.

Dave’s Reply:
Thanks for your electrical question Bruce .

Wiring a Motor for 240 Volts

Application: Wiring an Electric Motor.
Skill Level: Intermediate to Advanced – Best Performed by a Licensed Electrician or Certified Motor Technician.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester.
Estimated Time: Depends on experience with electric motors.
Precaution: Electric motors are best serviced by an experienced electrician or knowledgeable technician. Changes in the wiring of an electric motor should only be made after the electric motor circuit has been identified and turned OFF and Tagged.

Motors that are Designed for 120/240 Volts

The Advantages of a 240 Volt Motor

Wiring a 120/240 volt motor for 240 volts is as follows:


More about 220 Volt Wiring Diagram

Electrical Wiring

220 Volt Wiring Diagram
220 Volt Wiring Diagram
Wiring 220 Volt Electrical Outlet
Home electrical wiring includes 110 volt outlets and 220 volt outlets and receptacles which are common place in every home. See how electrical outlets for the home are wired.

This link is helpful as a Homeowner
Do-It-Yourself Electrical

How to Wire a Motor for 240 Volts

The following may also be helpful for you:

Dave's Guide to Home Electrical Wiring:

» You Can Avoid Costly Mistakes! «

Here's How to Do It:
Wire It Right with the help of my Illustrated Wiring Book

Great for any Home Wiring Project.
  electrical wiring  

Complete Guide to Home Electrical Wiring

Perfect for Homeowners, Students,
Handyman, Handy Women, and Electricians
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.

Learn more about Home Electrical Wiring
with my Online Video Course:
Basic Home Electrical Wiring by Example

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

6 Responses to “120 and 240 Volt Motor Wiring”
  1. Ed Lawlor says:

    I have a residential unit with a fan coil wired for 208/230 volt motor. I am replacing the unit with a 120 volt EC motor. Can I use the existing wiring circuit (use one leg) to power the new equipment? Did not want to increase customer costs with new 120 volt circuit home run.

  2. Dave Rongey says:

    Hi Ed,
    If the existing circuit is dedicated, and the amperage is within the specs of the new motor then it can be converted to be 120 volt at the panel and at the motor connections. However, you should understand that the 120 volt motor will require more amperage, and this may affect the performance of the unit. In cases such as this it is best to replace the motor with one of the same specs to make sure the unit is left in OEM condition. This may keep you out of a potential problem with the customer in the future, plus you will not have to make any wiring changes. 😉
    I hope this helps,

  3. Timothy says:

    Can I Wire Two 120volt Motors to a 240volt circuit?

    What if I have two 120v motors which operate at 14amps? I cannot run them on a single 20amp circuit.However, I have a 240 volt (4 wire) circuit which can handle much more amperage. If I was to wire one pole of each motor to the neutral and the remaining pole each to a separate hot wire (Having two 120v powers from one circuit) would that power each motor and not bust the amperage limit? Also, will there be any back-EMF effects through the neutral (which is shared)?

  4. Dave Rongey says:

    Circuits for Two 120volt Motors

    Hi Timothy,
    Using a multi-wire 4wire circuit for two 120volt motors would depend on the type of motors that would be connected and the application. However, due to the amperage of the 120volt motors as described, and the possibility of overloading a shared neutral it would be best to install two separate circuits, one dedicated circuit for each motor.

  5. William says:

    Need Wiring Diagram for a Robbins Myers Motor
    I have a old Robbins & Myers motor. The plate reads, 110/220, 1725 RPM, frame S204, M/S 4470, SN AC111/94.
    There is no wiring diagram. There are 6 leads, all the same color.
    They do have numbered clip, 1, 2, 3, 4, 8, 8.
    What is the connections to run on 110 volts.


  6. Dave Rongey says:

    Old Robbins and Meyers Motor Wiring Diagram
    Hi William,
    Unfortunately I have not been able to locate a wiring diagram for your Robbins and Meyers motor.
    I would suggest visiting the Google Groups page where there is some discussion about Robbins Myers motor wiring.
    Here is the link: Google Groups Robbins Meyer motor wiring
    I hope this helps,