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Electrical Wire and Cable

How to Wire a Generator Transfer Switch

The Basic Wiring Configuration for a Generator Transfer Switch: Each Wiring Termination must be correct for the Power Conductors of the Line or Load.
Neutral conductors are attached to the Neutral Terminal Block. All enclosures and equipment must be grounded and bonded. Common Misunderstandings or Mistakes when Wiring Generator Transfer Switches.

Generator Transfer Switch Wiring
Electrical Question #1 about Generator Transfer Switch:
I had a Reliance 31410RK manual transfer switch put in by a licensed electrician about a year ago. Powering it with a Honeywell 7000 watt generator. After a power failure the other day I started up the generator, connected the cord into the twist lock inlet outside to the switch, then went inside and started one by one transferring load to the generator.
At first the overhead light in the cellar went on, but dimly. But after that I wound up blowing up 3 power strips that had little or no load on them, blowing out 2 light bulbs, frying a TV cable box, and blowing out the ignition module of my gas boiler. Sparks were coming out of 2 of the power strips and one caught on fire.
After that the switch would not work at all and nothing shown on the meters when the generator is running. Funny thing is once before when I used it when the electrician had put in about half the circuits- sparks flew out of the boiler ignition (the box that steps down house current to 26 volts to light the boiler). After that time, the switch would not work, but after he returned to finish up wiring all the circuits, everything worked fine and we inspected it while using all the circuits.
The same things were hooked up and everything worked fine. But after the transfer switch failed now, I just hooked up the generator with a 25′ long 30 amp generator cord that inserts into the very same twist-lock receptacle on the generator, everything works fine. In other words, not using the transfer switch, just running a heavy generator cord into the house and plugging things into that, no problems.
My electrician is puzzled, he has not looked at it yet, what could cause this?

This home electrical repairs question came from: Frank, from Madison, New Jersey.

Electrical Question #2:

This electrical wiring question came from Glenn in Tampa, Florida.

Dave’s Reply:
Thank you for your electrical wiring questions.

Generator Transfer Switch Wiring Configuration

Skill Level: Advanced – Licensed Electrical Contractor, Not Recommended for Homeowners.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the generator and transfer switch.
Estimated Time: Depends on the type and size of the generator and transfer switch and the available access to the project area.
Precaution: Any existing electrical wiring within the immediate area that may interfere with the installation of the generator transfer switch may need to be relocated if necessary.
Important: Installing a generator and transfer switch must be well thought out and performed with a permit with all of the work being inspected.

The Importance of Proper Wiring Configuration and Isolation

The Basic Wiring Configuration for a Generator Transfer Switch:

Each Wiring Termination must be correct for the Power Conductors of the Line or Load.
Neutral conductors are attached to the Neutral Terminal Block.
All enclosures and equipment must be grounded and bonded.
NOTE: Some transfer switches may have the provision for transferring the Neutral Conductors.

Common Misunderstandings or Mistakes when Wiring Generator Transfer Switches

Not understanding the difference between:

Alternatives to a Generator Transfer Switches

IMPORTANT: All generator transfer switches and generator panels should be installed by a licensed electrician and all work must be inspected.

Portable Generators for Immediate Emergency Power

Portable generators are great for powering up a few devices by using appropriately sized extension cords without connecting to the home electrical system. Refer to the Operating Manual which comes with the Portable Generator for specific details and Safe Operation.

More about Generators and Transfer Switches

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 Section
The Importance of a Generator Transfer Switch
Generator Articles
Generator Questions and Answers

Home Electrical Circuits

Electric Circuit Listing

The size of the home electrical service panel is designed by calculating the square footage of the home and factoring in the code requirements for the electrical circuits that are required.

How to Install Home Lighting
Lighting Electrical Codes

Using Electrical Testers and Voltage Meters

Understanding Digital Volt Meters

When working on home electrical wiring using voltage meter can play an important part in electrical safety. Electrical testers and voltage meters enable you to identify electrical circuits and help prevent the possibility of accidental electrical shock.
Types of Electrical Testers
Using Electrical Testers and Voltage Meters

Electrical Calculations and Formulas

» 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, Handywomen, 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.

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

4 Responses to “How to Wire a Generator Transfer Switch”
  1. Arnold Strzelecki says:

    Do you need a 50 amp for the switch?

    • Dave Rongey says:

      Hi Arnold,
      The size and amperage of the electrical components that will be installed for a generator system are determined by the size of the generator, and the electrical circuits that will be placed on generator power.

      I hope this helps,

  2. Arnold Strzelecki says:

    I need a book or instructions about how to wire a 6 circuit transfer switch. Most electrical books do not have that info. Just basic electrical wiring.

    • Dave Rongey says:

      Hi Arnold,
      The wiring for a 6 circuit transfer switch will depend on the specific setup at your location, and the type of transfer switch or generator panel that you get.

      I hope this helps,


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