How to Wire a Generator Cord

Should a generator cord have 3 or 4 wires? How to Wire a Cord for a Generator, Connecting a 3-Wire and 4-Wire Cord to a Generator, Generator Cord and Connector Amperage Ratings.

Wiring a Generator Cord
Electrical Question: Should a generator cord have 3 or 4 wires?

I am wiring a cord for my generator, would you suggest 3 conductor or 4 conductor cable?

My Generator Specifications

• I have an older gas powered generator and it is rated at:
  • Voltage: 120/240.
  • Amps: 41.7/20.8.
  • Single Phase.
  • The outlets are one duplex NEMA 6-20R and one duplex of 5-20R.

My Generator Project

• I want to split the 240V into 2@120V circuits. Looking at the wiring diagram of the 6-20R, I see 2 hot leads and 1 ground lead.
• My guess is that I bond the neutral to the ground and so my wiring would be one hot and the neutral/ground to each new 5-20R.
• So the result would be a ‘Y Pigtail’ with a 6-20P (240) and 5-20Rs on the other end.
• Would you suggest 3 conductor or 4 conductor cable for the pigtail.

Thank you.

This electrical wiring question came from: Ray, from Costa Mesa, California.

Dave’s Reply:
Thanks for your electric wiring question Ray.

How to Wire a Cord for a Generator

Application: Wiring a Generator Cord.
Skill Level: Advanced – Best performed by a Licensed Electrical Contractor.
Tools Required: Electricians pouch of hand tools.
Estimated Time: Depends on the type and size of the generator output, the specific receptacle, and the available access to the project area.
Note: Generator power should always be wired through an approved transfer switch or circuit interlock device. Any part of the home electrical system must NEVER be back-fed using a cheater cord. Back-feeding is extremely hazardous for the home, the occupants and the electric utility company repairmen.
Important: Installing a generator and transfer switch must be well thought out and performed with a permit with all work being inspected.

Wiring a Generator Cord

• Generator power which will be used for multiple circuits should first connect to an electrical distribution panel.
• A “Y” adapter should not be connected to a generator.
• If the generator has a 3-wire receptacle which states that it is 240 volts then a separate  neutral is not present, therefore a 120 volt circuit is not available.
• You can only obtain 120 volts from the receptacle which states that it is 120 volts.

Connecting a 3-Wire and 4-Wire Cord to a Generator

• If the receptacle on the generator is a 3-wire type then a 3-wire cord and male connector body should be used.
• If the generator receptacle is a 4-wire type then a 4-wire cord and male connector body should be used.

Generator Cord and Connector Amperage Ratings

• Generator Receptacle Outlet Examples:
  • A NEMA 20R receptacle  indicates a 20 amp receptacle.
  • A NEMA 30R receptacle indicates a 30 amp receptacle.

Home Generator Cords

• The connecting cord to the generator should be connected to a transfer switch, generator circuit panel, or an approved interlock device which is properly sized which will ensure that only one source of power is connected and ON at any given time.

More about Home Generators

Home Electric Generators

• Home Electric Generators

• This series covers a wide variety of topics all about home generators including sizing, selecting, connecting and safely operating this all important addition to your home.

Generator Transfer Switches are the Safe Link To Powering Your Home

The Generator Transfer Switch

• See how a transfer switch ensures a safe isolation of the electric utility company and your home generator.

» 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. Complete Guide to Home Electrical Wiring Perfect for Homeowners, Students, Handyman, Handywomen, 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.

Be Careful and Be Safe - Never Work on Energized Circuits!
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Home Electrical Wiring and Electrical Repairs Please Note: Unless otherwise posted, please refer to the following Guidelines when working on Electrical Projects: Skill Level: Intermediate to Advanced - Electrical Repairs and Circuit Wiring is Best Performed by a Certified Electrician or Licensed Electrical Contractor. Electrical Tools Required: Basic Electricians Pouch of Hand Tools, a Voltage Tester and a Multi Meter. Estimated Time: Depends on personal level experience, ability to work with tools, work with electrical wiring, and the available access to the project area. Precaution: Identify the project circuit, turn it OFF and Tag it with a Note before working with the wiring. Important: Modifying existing electrical circuits or installing additional electrical wiring should be done according to local and National Electrical Codes, with a permit and be inspected.

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