Generator Transfer Switch Using Circuit Breakers

Can You Make a Generator Transfer Switch Using Circuit Breakers? How to Use a Circuit Breaker Interlock Kit for a Generator Transfer Switch. © By: Dave Rongey

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Interlock Generator Transfer Switch
Electrical Question: Can You Make a Generator Transfer Switch Using Circuit Breakers?

• I want to connect my generator to my House panel during a power outage.
• I have a meter with a 200 amp main breaker which also has a panel for breakers.
• Is it possible to run electricity backwards through a circuit breaker?
• I want to use the 50 amp garage breaker in this panel as a source from my generator to my house.

My plan for an outage would be to trip the main breaker and plug a home made cord into my generator and garage outlet.
Please advise, Thanks.

This electrical wiring question came from Colin, who is a Homeowner from Fruit Heights, Utah.

Dave’s Reply:
Thanks for your generator question Colin.
Yes Colin, a typical circuit breaker works the same way protecting the circuit in both directions.

Generator Transfer Switch Circuit Breaker Interlock

See more about the Types of  Generator Interlock Kits:
Generator Interlock Kit

• Skill Level: Advanced – Best installed by a Licensed Electrical Contractor.
• Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the generator and transfer switch or circuit breaker interlock kit.
• Estimated Time: Depends on the type and size of the generator and transfer switch and the available access to the project area.
• Important: Installing a generator and transfer switch must be well thought out and performed with a permit with all work being inspected.

How to Use a Circuit Breaker Interlock Kit for a Generator Transfer Switch

PLEASE READ THIS CAREFULLY!

• The following information is to be used for a Main Electrical Panel ONLY.
• This cannot be done from a Sub Panel
• The Circuit Breaker Interlock can only be used at the Main Panel.

How a Circuit Breaker Interlock Kit Works

The photo above is from a job site where I installed a Circuit Breaker Generator Transfer Interlock device which allows either the main electrical panel breaker or the generator feed circuit breaker to be on, but never both.

The interlock kit must be properly installed with the appropriate circuit breakers and then may only be used with the panel cover positioned and securely mounted in place. Consult the installation instructions of the specific interlock kit that is obtained.

• Selecting a Generator Interlock Kit
  • This serves as a required Generator Transfer Switch and is listed with UL.
  • The circuit breaker for the generator power must be sized for the capacity of the generator, or match the circuit breaker that is on the generator, (consult your generator manufacturer specifications.).
• Avoiding Generator Overload
  • This set up works well, but keep in mind that you may need to turn off some circuits to avoid overloading the generator and or causing a voltage drop condition.
  • We found this to be the case if our refrigerator and septic pump came on at the same time, so I had to turn off the breaker for the septic pump and run it later.
• Generator Transfer Switch Required by Electrical Codes
  
  • IMPORTANT: A transfer switch or mechanical device such as the one shown in the picture must be installed to provide separation between the electric utility power and the generator power to prevent hazardous electrical conditions and to be compliant with electrical codes.
  • The home electrical panel circuit breaker for the generator feed must be sized to the capacity of the generator.

• Sizing the Interlock Transfer Switch
  • The amount of power available to the home will be limited to the Size and Type of generator that you have.
  • Not all generators have the same design features such as voltage regulation.
  • The circuit breaker interlock kits for generator transfer switches are available for a variety of electrical panels, circuit breaker sizes and styles.
  • All home electrical generator systems and transfer switches must be installed with a permit and be inspected as per your local building department or jurisdiction.

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