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  What is a Generator Interlock Kit?

The Interlock Kit is a device that creates a mechanical interference between the main breaker and a generator back feed breaker so that both breakers can not be turned on at the same time. The "interlocking" of these breakers protects the public power system by insuring that your generator does not accidentally put power on the utility power grid.

Utilizing the kit also improves safety in the home while using a portable generator by eliminating the need for extension cords to be run throughout the home. One simple connection between the generator and the generator convenience outlet allows the generator to provide power to all the circuits in the home; up to the capacity of the generator. See drawing. Remember, when a light is turned off it uses no power but with the Interlock Kit, all the lights in the home will be available as you move from room to room.

Interlock Kits are intended to be installed by qualified electricians. The Kits are designed, manufactured, and tested by Wyle Labs are to meet the National Electrical Code and the National Fire Protection Code. Wyle Labs is a nationally recognized testing laboratory that tests to UL and other standards. Test results are available from Wyle Labs.

What does an Interlock Kit look like?

The image to the right shows an example of what an Interlock Kit looks like on a panel. We stock over 50 different Kits so yours may look different - but the concept is the same. When the Kit installation is complete, it becomes a permanent part of the front cover to the panel.

What do I get in my Interlock Kit?

The Interlock Kit includes the actual interlock mechanism, mounting hardware, back feed breaker retaining strap, required labels, drill bit for mounting holes, and detailed instructions for installation and operation.

Other items that you will need including the generator convenience outlet the generator back feed breaker, and the generator cord are generally available from your local supplier. Generator Interlock Technologies offers these options if you wish to purchase everything necessary for the installation from one location. Please see our online store for availability.

How do I choose the correct Kit?

While using the Interlock Kit is easy, care must be taken to order the correct kit for your panel board. The best way to order is to determine the manufacturer of the panel by looking inside the panel door. Note the location and size (100 amp, 150 amp, or 200 amp) of the main breaker and its location compared to the branch circuit breakers. Pay particular attention to the dimensions between the main breaker and branch circuit breakers. Also note if the main breaker switches turns on and off by moving up and down or left and right.

With the above information, go to the website and use the Interlock Kit Selection when the list of manufactures pops up, use the appropriate button to select the manufacture of your panel. Multiple pictures of panels by that manufacture will be displayed giving the critical dimensions for each panel. Using the pictures and the dimensions from your panel, select the kit you need. Note that many manufactures made panels that were marketed under other names (ITE and Siemens as an example) so you may find the same panel listed under two brands. Some areas of the country utilize panels known as "Combo Meter Mains" which houses the utility meter and some breakers in one box or panel located outside. We offer many kits for these applications and each are noted accordingly.

If you still have questions or believe that you have a panel that is not shown in our selection please email us at: or call (804) 726-2448. We'll be happy to help you, and even offer custom kits for difficult situations.

How does the Interlock Kit work?

Your panel board is a distribution and protection system for electricity in your home. Power is fed through the utility into the panel. From here it is run across the different circuit breakers and out into the rest of your home. The Interlock Kit allows you to safely disconnect your panel from the utility feed and switch it over to the generator which is being fed through a new generator breaker. The Interlock kit allows only one of these feed systems to be operational at one time protecting the panel from being overloaded by both sources.

With this one connection you can now use anything in your home because all the circuits in your home can be activated through the breakers in your panel. It also eliminates running unsightly and potentially dangerous extension cords to various parts of your home and the need to plug and unplug appliances and lights.

Once the Interlock kit is installed it is quick and easy to transfer power from utility to generator in case of a power outage. And it is just as easy to return once the utility power has been cut back on, just reverse the procedure below.

  1. Turn main breaker to the "OFF" position
  2. Turn all branch circuits to the "OFF" position
  3. Slide Interlock plate up (down in some kits)
  4. Connect and start generator
  5. Turn generator breaker to the "ON" position
  6. Turn on essential circuits one at a time.

WARNING: Allow appliances to start before engaging the next circuit

Note: Large loads such as water heaters, microwaves, dryer etc may not all be able to run at the same time. Breakers themselves do not use power unless something in the room that they feed has been cut on so it is fine to have the breakers that feed all the bedrooms, living room etc. on so that you will have the power available for lights and such as you need them. Check the What I can run with my generator section to see what can be run at one time with the larger loads.

If you have gas, oil, or propane heat you can run your furnace or boiler and keep warm. However if you have electric heat most generators under 10000 watts will not have the capacity to run it. That is the same for central air as well. The Interlock Kit will handle any size generator though so if you have an electric heat pump or want to run your air conditioning unit then you should consider a 12000-watt or 15000-watt generator.

Do Interlock Kits and optional parts carry a warranty?

All products listed and sold by Generator Interlock Technologies, LLC are covered by a satisfaction guarantee for 30 days or you will be refunded for the full amount of the products ordered, shipping charges not included in refund. After 30 days all sales are final. To receive full refund the product or products ordered must be returned and must be without altercation or damage not considered normal wear and tear as a result of use or installation. Any questions can be directed to Generator Interlock Technologies by using the contact information setup on this site.

What I can run with my generator?

You can run as many lights and appliances as you want as long as you do not exceed the capacity of your generator. A 6000-watt generator can run 60 - 100 watt light bulbs at one time. This is why you should keep all your breakers feeding the lights and rooms of your house on with the exception of your kitchen and bathrooms. Just add up what you would like to run and make sure to stay under your generators full load capacity. Note that it is also a good idea to not load your generator past 80% for long periods of time (more that one hour) unless you have an industrial grade model. Most appliances have the wattage clearly listed on the nameplate. If only Amperes and Volts are given just multiply them together to get watts. (10.2 Amps x 120 Volts = 1224 Watts). Below is a guide to what various appliances use (check your appliances for actual wattage numbers as they can vary from one to the next).

Typical appliance wattage

  • Electric water heater - 4500 watts
  • Microwave - 1600
  • Toaster oven - 1800
  • Stove top element (one) - 2200
  • Hair dryer - 1500
  • Well pump - 2000
  • Basement sump-pump - 900
  • Refrigerator - 700
  • Freezer - 700
  • Furnace or boiler (gas, oil, or propane) - 700

Even with only a 6000-watt generator, you can do almost anything in your home that you would normally do - just not all at once.

For instance, you can turn on the hot water heater at night when little else is running and have a full tank of hot water in the morning; keep it off during the day so that you can have available power to use other appliances in the house. If you have gas, oil, or propane heat you can run your furnace or boiler and keep warm. However if you have electric heat, most generators under 10000 watts won't have the capacity to run it. The same goes for central air. The Interlock Kit will handle any size generator, so if you have an electric heat pump or want to run your air conditioning unit then you should consider a 12000-watt or 15000-watt generator.

How do I connect my generator breaker to my generator?

A Generator Convenience Outlet is set near your generator and is hard wired (NM wire) to your panel. An extension cord that is matched to your generator is used to connect the generator to the Generator Convenience Outlet. The extension cords are a standard 10 ft length but can be made to 20 ft and 40 ft lengths and are sold only in conjunction with our Generator Convenience Outlets because of the numerous possible combinations with other manufacturers outlets. Note: the Generator Convenience Outlet's amperage must match that of the generator breaker.

How do I use the generator to feed my panel?
Back Feed Breakers (generator breaker)

The back feed breaker is how the power from your generator gets into your panel and the breaker style must match the style of your panel. You can either order the amperage breaker that you need (check your generators owners manual) or just tell us the size of the generator you plan to use and we can match the size and style of the breaker for you.

Generally, people use a 30 amp back feed breaker and convenience outlet for generators up to 8,000 watts and a 50 amp back feed breaker and convenience outlet for larger units. For generators with outlets greater than 50 ampx, please consult the factory.

How do I free up spaces for my Back Feed Breaker?
Piggyback Breakers

To install the back feed breaker you will need 2 or 3 available spaces (to find the number of free spaces you will need, look in the panel requirements on the panel selection page for your kit. If you do not have enough free spaces in your panel you will need to order one piggyback breaker for each space that you need to create (A piggy back breaker creates two spaces from on space.) If you order from us we will select the correct style and number of piggyback breakers that you will need based on the InterLock kit and the information that you provide for us. Please note that if you remove a 15 Amp breaker from your panel you should order a 15 Amp piggyback breaker to replace it. This also means that you should have another 15 Amp breaker somewhere in your panel to pair it with. If you are removing a 20 Amp breaker then the same should apply. If you need to pair a 15 Amp and a 20 Amp breaker, then you should order a 15/20 Amp piggyback breaker.