CH Generator Interlock Kit

Transfer Power Safely With A Main Breaker Interlock Kit

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Two Ideal 30-454 Wing-Nut Blue Wire Connectors being used to splice short pieces of #8 copper wire to the existing stove feed wires
Two Ideal 30-454 Wing-Nut Blue Wire Connectors being used to splice short pieces of #8 copper wire to the existing stove feed wires

Above is a close shot of two Ideal 30-454 Wing-Nut Blue Wire Connectors being used to splice short pieces of #8 copper wire to the existing stove feed wire.  This was necessary in order to relocate the existing stove circuit breaker down a few spaces to make room for the generator circuit breaker.

The generator circuit breaker with the #10 wires attached
The generator circuit breaker with the #10 wires attached

The generator circuit breaker above with the wires attached.  The empty circuit breaker space below the two pole 30 amp generator breaker is needed for the operation of the interlock kit.

Note the label above the Ideal 30-454 Wing-Nut Blue Wire Connectors.  It is attached to a strap that is holding the generator circuit breaker in place and is required as per the interlock kit instructions.  Without the label attached, this interlock kit installation would fail the electrical inspection.

It is important to follow the instructions that came with the interlock kit.  This will ensure a safe operation, code compliance, and pass electrical inspection.

Main breaker and the generator breaker with the panel cover removed
Main breaker and the generator breaker with the panel cover removed

An inexpensive circuit tracer is helpful when trying to identify important circuits before you have a need to turn on the generator.  You could also just flip the circuit breakers off and on to see what goes out.

Generator feed wire neutral and grounding conductors on same terminal bar
Generator feed wire neutral and grounding conductors on same terminal bar

The upper red arrow points to the generator ground connection.  The lower red arrow indicates the white neutral wire connection.  This is the main electrical panel so the ground and neutral are connected on the same terminal bar.

In a sub-panel the ground and neutral would be kept separate.  Only a generator with an unbonded internal neutral/ground can be used to temporarily power this house.

Not all portable power generators are the same.  A generator used to power a house must not have an internal neutral/ground bond.  This is because the main electrical panel already has a neutral/ground bond where the neutral and ground are connected together.

A portable generator that has an internal neutral/ground bond is used in areas where the generator is the sole source of power such as a remote construction site.

The generator must have a 30 amp L14-30 twist lock receptacle on it.  For a 50 amp installation the generator must have a 14-50P straight receptacle on it.

Drilled and sanded holes that were made in the circuit breaker panel cover using the included drill bit
Drilled and sanded holes that were made in the circuit breaker panel cover using the included drill bit

The photo above depicts the holes that were made in the circuit breaker panel cover using the included drill bit.  It is also required to scrape and file the perimeter of the holes so that the screws can make good contact for grounding of the interlock kit.

The drilling of the holes to mount the interlock kit onto the electrical panel cover must be precise.  The manufacturer of this particular interlock kit provided a drill bit for that very reason.

It is important to get the holes in the exact location specified in the instructions.  I use the interlock kit as a template to mark the hole locations.  The area around the drilled holes must be scraped or sanded down to bare metal to maintain grounding continuity onto the interlock kit.

The holes in the circuit breaker cover with the screws in them and the interlock kit mounted on the front side
Here are the holes in the circuit breaker cover with the screws in them and the interlock kit mounted on the front side.
Completed interlock kit installation on an older Cutler Hammer type CH circuit breaker panel
Completed interlock kit installation on an older Cutler Hammer type CH circuit breaker panel

Above is the completed interlock kit installation on an older Cutler Hammer type CH circuit breaker panel (Also known as a Load Center).  The interlock kit functions as a transfer switch without having to install a separate box with additional wiring that also requires additional wall space.

In this installation a Cutler Hammer blank panel seal was installed in the empty circuit breaker space below the generator two pole circuit breaker.  The empty space is needed for interlock kit freedom of movement.

This interlock kit installation took me approximately fours hours to complete with all materials and needed tools on site.  I also spent another fours hours on the initial meeting with the client, preparing and mailing the estimate, receiving and depositing the first payment, applying for the electrical permit, purchasing materials, and arranging for the final inspection.

Red tape marks on some of the circuit breakers so that the homeowner can easily identify some of the critical circuits that will require generator power
Red tape marks on some of the circuit breakers so that the homeowner can easily identify some of the critical circuits that will require generator power

The red tape marks on some of the circuit breakers are there so that the homeowner can easily identify some of the critical circuits that will require generator power.  These include the heating system, the well pump, and the refrigerator.  The bathroom and kitchen lighting circuits are also identified.

Installed Interlock kit on a Cutler Hammer Circuit Breaker Panel
Installed Interlock kit on a Cutler Hammer Circuit Breaker Panel

In the photo above is the completed installation of an interlock kit on a Cutler Hammer Circuit Breaker Panel.  The interlock kit prevents the generator circuit breaker, located in the upper right column, from being “On” at the same time as the main circuit breaker.  The labeling is an integral part of the installation and must be in place to pass inspection.

In this installation the interlock kit can get pushed down after the main circuit breaker is pushed off.  Once down, the generator circuit breaker can be safely turned on.  This operation prevents generator power from being on at the same time as the utility company power.

The final connection is made using an L14-30 generator cord to connect the portable generator to the generator inlet.  The female end of the generator cord is connected to the generator inlet.  The male end is plugged into the twistlock receptacle on the generator.  This should be done with the circuit breaker on the generator in the “Off” position for safety.

Once the generator cord is connected and the generator is running, you can turn on the generator circuit breaker and then go inside the house to the main circuit breaker panel to shut off the main circuit breaker and each individual branch circuit breaker.

Then turn on the generator circuit breaker in the main panel and turn on the circuits that you have previously chosen to be powered from the generator.  Of course the beauty of the interlock kit is that you can pick and choose what circuits to turn on as needed and turn off when not needed.

For a 50 amp portable generator connection a 14-50P to CS6364 power cord would be used.

My YouTube video of this interlock kit installation

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