Page last updated Dec 15, 2023 @ 05:13pm

Panel Interlock Kits


Select brand of load center breaker panel at right ->
The NEW solar interlocks are on the same pages        


What is a Panel Interlock Kit?

Safety is an important part of our lives. Safety for your person and safety for your investments and there isn’t a much more important investment than your home. Our breaker panel load center Interlock kit (also referred to as a breaker lockout) allows you to connect your portable generator to your electrical system safely without danger of backfeed to utility power. With the generator feeding your home electrical system it eliminates the need to run extension cords into your home, which is both a fire and a safety hazard. Our kits are designed to be installed by qualified electrical personnel and meet the strict requirements of the National Electrical Code and the National Fire Protection Code.  These kits are Listed to UL 67 by an independent lab for use in the USA.  Unfortunately they are not approved for use in Canada.   Made in USA  .  

This kit provides the safety for your home electrical system that you need to protect your investment. We offer Interlock kits to fit most panel boards including a full line of accessories to connect your portable generator to your home electrical system.


How does the Interlock kit work?

Your panel board is a distribution and protection system for electricity in your home. Power is fed from the utility into the panel. From here it is run across the different branch 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 the same time which prevents both sources from being connected together.  Without an interlock or a transfer switch there is always a chance that someone could forget to open the main breaker resulting in a danger of electrocution to linemen, destruction of your generator and fire.  For more on these risks see our safety page.

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. Allow appliances to start before engaging 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 What I can run with my generator 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.


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

The back feed breaker is used for the generator input connection to the panel.  To install the back feed breaker and interlock you will need 2, 3 or 4 free spaces (look in the panel requirements for your kit to find the number of free spaces you will need which is on the kit selection page) in your panel. If you do not have enough free spaces in your panel you will need to obtain one piggyback breaker for each space that you need to create. Piggyback breakers are sometimes called half-height breakers because they are manufactured with two breakers in the space that one breaker normally takes.  However, they are normally available ONLY in 15 and 20 amp ratings.  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.  If you cannot free-up the necessary spaces then you CANNOT use these interlock kits.


What does a typical installation look like?

In additional to the interlock kit we can provide the generator cord, outdoor power inlet box, generator load meters and utility power return alert as shown below.  Items on this image are clickable.


How hard is it to install interlock?

Complete installation instructions are included with every kit.  Kit comes with back plate, front slider plate, double-stick pads, screws, drill bit, thread lock and labels.
     1) Disconnect power to panel.
     2) Mount backing plate in proper position on panel cover with double-stick pads.
     3) Remove panel cover.
     4) Relocate branch breakers to free up necessary space for generator back feed breaker and interlock.
     5) Install generator back feed breaker.
     6) Install retaining strap around back feed breaker and label.
     7) Drill 3 or 4 holes through panel cover using backing plate as a guide.
     8) Remove burrs and file away spot of paint to allow for good electrical ground contact.
     9) Install front slider plate with included screws.
    10) Turn off generator and main breakers and re-install panel cover.
    11) Test interlock for proper operation.
    12) Apply thread lock to interlock screws.
    13) Attach labels.

These kits should be installed, tested, serviced and maintained by qualified personnel.  No responsibility is assumed by the manufacturer Generator Interlock Technologies, LLC or No LLC for any consequences arising out of the misuse of this product.


What is included in the kit?

The kit includes a specially designed back plate and front plate to fit the specific breaker panel, binder posts, binder screws, drill bit, thread lock, install instructions, labels for: main breaker, generator breaker, operating instructions, danger, retaining strap, retaining strap label.  Click here for an image or a typical kit contents.  Due to the wide variety of breakers available, the kit does not include the branch breaker that is used as the generator backfeed breaker.  These are usually easy to purchase locally.  The outdoor inlet box, building wire and generator cordset should be purchased separately.


Is this equivalent to a transfer switch?

These interlock kits are a perfect alternative if there is no room for a separate transfer switch or transfer panel on the wall next to your breaker panel, or on the outside of your house near the power company meter.  These kits are Listed to UL 67 by an independent lab.  However, these interlock kits DO require:
     * modification of your load center breaker panel
     * free branch breaker spaces
     * proper installation and check of operation
Unlike many other breaker-based factory-built transfer switches, these kits are not functional when the front panel is removed.


How do I avoid generator overloading?

Using these interlock kits to provide power to your whole breaker panel can result in overloading your generator.  Damage to the generator and some appliance loads can result from these overloads.  To avoid this possibility we recommend meters be installed on your generator feed to the panel.  This will tell you how much load is being carried at any time and how much spare capacity is available for additional loads.  With this information you can determine which branch circuits in your breaker panel can be turned on.  Click here for our wide selection of generator meters.


How do I know when utility power has been restored?

During a power outage while the generator is powering your panel the main breaker will be off.  Therefore you will have no way of knowing when utility power has been restored (unless you can easily see neighbors' lights come back on).  We sell a low cost solution to this problem.  See the PowerBACK™ utility power return alert module.


Solar Interlock Kits now available for use with PV input breaker


The KS- series interlock Kits are now available for many breaker panels that have a third input branch breaker that is connected to a Solar Photo Voltaic (PV) system. Generally, this breaker must be turned off when a backup generator is connected to the breaker panel. These KS- series interlocks insure that BOTH the utility main breaker AND the solar input breaker are turned off before turning on the generator breaker. Like the K- series interlocks, these KS- interlocks are code compliant to the National Electrical Code (NEC) and certified to UL standards. And to comply with these requirements, the interlock is designed to reach the far end of the branch circuit space from the main breaker. This is where the PV input breaker must be located. For easy selection the KS- series solar interlock kits are highlighted on our web pages with a yellow background.

Currently available for selected Eaton Cutler-Hammer and Square D panels, with more being added continually. If you do not see the configuration you need, email us a photo of your panel.




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