Is it Safe to Backfeed a Generator?

A generator can be a life-saving device during an extended power outage in your home.  It can be a hassle to run extension cords from outside, where the generator should be located, to the needed appliances.  This means running long extension cords through doors or windows, which could result in wind, rain, or snow entering your home. Going this route means outdoor extension cords should be protected from bad weather.  It could also be a way for critters or people to enter, thus posing a safety hazard.

There may be an easier, safer way to provide power via a power transfer system.  This must be done by a certified electrician, but it can save time and frustration in a time of need.  It is called backfeeding.

Backfeeding is a means of supplying power through the main electrical panel to your home.  When the main power is disrupted coming into the home from your electrical service, the generator can be connected via a transfer switch to send power through the electrical panel.  This allows power to the circuits needed to comfort and survival:  furnace, a/c, refrigerator/freezer, stove, and lights, for example.

It is crucial that you never attempt to backfeed power unless the main breaker(s) is turned off.  Power from the generator is feeding back into the electrical box and out to the power lines.  Without turning off the main breaker(s) you can cause a lineman to be electrocuted while attempting to repair damaged lines.  It can also cause a fire. 

Never attempt to plug the generator into a wall, range, or dryer outlet to feed back into your home. 

Safety should be your primary concern in connecting the generator to your home’s electrical panel.  Therefore, a certified electrician should be consulted and hired to place the circuit breaker, transfer switch, and power inlet box in your home to provide the power transfer system.  Note that backfeeding falls under your area’s electrical codes and only a local certified professional will know your specific codes.

You must remember to turn off the main breaker(s) before turning the transfer switch to generator use.  Most transfer switches are manual; however, an automatic switch can also be installed.  There is a safety device that can be installed inside the electrical panel that will make sure the main breaker(s) is off.  It is called an “interlock”.  This device is installed at the main breaker with the circuit to the transfer switch just below.  It will not allow the transfer switch to be turned on unless the main breaker is turned off.  The video below shows how the interlock is used. 

Backfeeding your generator through your existing home’s electrical panel! Using an Interlock! 

Guidelines for using your generator to backfeed into your home need to be followed carefully.  Consult your generator manual for instructions as well as following the steps provided by your electrician.

Your generator should have enough wattage to power the needed circuits in your home.  Generally, a 5000-watt generator will power up to six circuits.  If you turn on more circuits than your generator can power, a fuse/breaker will blow (shut-off), which protects your generator from damage.  Only turn on the circuits that are necessary for comfort and survival and stay within the power output of your generator.

The generator should be a minimum of 10 foot away from your home.  This is a safety precaution to prevent exhaust fumes or potential fire from the generator.

A power cord, called a gen-cord or stinger cable, is connected to the generator and then to the outdoor power receptacle, which your electrician will have installed as part of the power transfer system.  This cord will be of commercial grade and have two male ends.  Depending on the output in amps of your generator, the plugs will be either 30-amp or 50-amp.

So how does a transfer switch work? The transfer switch is installed on the outside of the electrical panel.  Wiring to the outside of the home and the outdoor power receptacle is connected to the transfer switch.  If you are not using an interlock device on your electrical panel, the following steps are generally used for a manual transfer to generator power.

  1. Turn off all the circuits in the transfer switch
  2. Connect the generator to the outdoor power receptacle using a gen-cord or stinger cable.
  3. Start the generator.  Allow it to run for a few minutes to warm up.
  4. Flip the transfer switch breakers from “line” to “generator” power.
  5. Turn the household circuits on one at a time to only power the needed appliances.  Do not overload the generator.

To return power to the line once power has been restored:

  1. Flip the transfer switch breakers from “generator” to “line” power.
  2. Turn off the generator.
  3. Disconnect the gen-cord stinger cable.

Safety is the primary consideration for utilizing backfeed.  Never attempt to do the wiring yourself.  This is the one time that a DIY project should be done by a professional that knows the electrical codes for your area.

Pros for backfeeding power to your home:

  • Eliminates extension cords to every appliance
  • Provides security and safety by having a certified electrician install
  • Can protect linemen and others
  • Is easier and convenient to switch power

Cons for backfeeding power to your home:

  • Having multiple extension cords run into the home
  • Cost of hiring a certified electrician
  • Not remembering to turn off the main breaker and backfeeding into the power grid
  • Electrocuting a lineman or others
  • Disregarding safety measures
Is it Safe to Backfeed a Generator?

FAQ

Can I backfeed through my dryer or range outlet?

Absolutely not.  This is a dangerous way to send power back into your home.  You risk damaging your home’s electrical system, as well as potential harm to yourself or others. 

What is an interlock for backfeeding?

An interlock is a device installed on your electrical panel that acts like a transfer switch.  It is a safety measure that prevents forgetting to turn off the main breaker(s) when switching to generator power. 

What type of power cord do I need for my generator to backfeed?

The type of power cord is called a gen-cord or stinger cable.  It is a commercial grade cord with two male ends.  Depending on the amperage that your generator produces, the plug ends will either be 30-amp or 50-amp.  It plugs into the outdoor power receptacle on your home, which is connected to the transfer switch at your electrical panel.

Why do I need a transfer switch to backfeed my home?

A transfer switch is required to allow power from your generator to flow back into your home’s electrical system.  It is a safety tool that is connected to your electrical panel and allows you to switch incoming power from the electrical grid source to your generator.  If connected properly (we recommend using a certified electrician), it protects linemen from electrocution by turning off the main breaker to the home so no power flows back into the power grid.

What do I need to do if I run extension cords from my generator?

When using a generator to power appliances directly, you are by-passing the home’s electrical system. Power is coming from the generator to the appliance, so nothing is backfeeding into the electrical panel or power grid. As a safety measure, you may turn off the main breaker(s) on your electrical panel until normal power is restored.

Can I install a transfer switch myself?

It is highly recommended that a certified electrician be consulted and hired to install a power transfer system.  This involves intricate wiring between the electrical panel, transfer switch and outdoor power receptacle.  In addition, due to varying electrical codes across the country, your professional electrician will be able to ensure that your home’s power system meets or exceeds the guidelines.

What size plug do I need for my generator cable?

The amperage output of your generator will determine the size of the plugs needed at the ends of your cable.  It will either be a 30-amp or 50-amp plug.

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