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Reliance PB50 generator inlet with the wires pulled into the back of the box, but no connections are made
Reliance PB50 generator inlet with the wires pulled into the back of the box, but no connections are made.

A 3/4″ plastic button type Romex connector was used to secure the cable to the back of the Reliance PB50 generator inlet box.

Reliance PB50 generator inlet with the interior wiring exposed and the equipment grounding conductor spliced without a wire connector
Reliance PB50 generator inlet with the interior wiring exposed and the equipment grounding conductor spliced without a wire connector.

As shown above, I always twist the wires tightly together with my Klein linemans pliers before I screw on a wire connector.

Reliance PB50 generator inlet with the interior wiring exposed and the equipment grounding conductor spliced with a wire connector
Reliance PB50 generator inlet with the interior wiring exposed and the equipment grounding conductor spliced with a wire connector.
Reliance PB50 generator inlet mounted on the outside of the house
Reliance PB50 generator inlet mounted on the outside of the house.

After I took the pictures of the inlet box, I put a bead of caulk across the top of the back edge where it comes in contact with the house siding.  This is to prevent water from getting behind.  I always use an outdoor clear gutter/flashing caulk as it seems to last the longest.  Caulk can be a little messy to work with which is why I took the pictures beforehand.  I did not want to get caulk on my camera or phone.

Reliance PB50 generator inlet with the cover open so that you can see the twistlock prongs
Reliance PB50 generator inlet with the cover open so that you can see the twistlock prongs.

I wired this for 50 amps, but the client did not have a generator big enough yet (12,000 watts) for that kind of power.  So I made them a 50 amp female (CS6364) to 30 amp male (L14-30p) short adapter cord so they could at least use their 6000 watt generator until a larger one was purchased.  The ground continuity is established through the center pin which is different from smaller twist lock plugs and receptacles that have a fourth twist prong.

Square D interlock kit mounted on two type QO circuit breakers with the panel cover off. The red arrow points to the mounting screw for the interlock kit.
Square D interlock kit mounted on two type QO circuit breakers with the panel cover off. The red arrow points to the mounting screw for the interlock kit.

The close photo above depicts the Square D #PK4DTIM4LA Manual Transfer Equipment Kit circuit breaker interlock with the retainer for keeping the circuit breakers in place.  It was very simple to install.  Installation instructions are included with the kit.  The red arrow indicates where the retainer was screwed to keep it in place.

Square D interlock kit mounted on two type QO circuit breakers with the panel cover on
Square D interlock kit mounted on two type QO circuit breakers with the panel cover on.

In order to pass inspection it is necessary to use equipment and accessories that have been approved by Underwriters Laboratories (UL) or another recognized testing laboratory.  The interlock kit and load center manufactured by Square D are fully approved.  This job passed inspection.

A completed generator sub-panel with a Square D generator interlock between the main circuit breaker and the generator circuit breaker with written instructions on how to operate it posted on the sub-panel cover door
A completed generator sub-panel with a Square D generator interlock between the main circuit breaker and the generator circuit breaker with written instructions on how to operate it posted on the sub-panel cover door.

It’s important to note that this type of portable generator hook up can only use a portable generator that is not bonded internally.  This means that the neutral and the ground are not connected together.  They are already connected together inside of the main electrical panel in the house as required by article 250.92 in the National Electrical Code.  Connecting them together in the generator can cause problems, particularly with GFCI circuit breakers.  When purchasing a portable generator look carefully at the packaging or contact the manufacturer before purchasing to determine if the generator is bonded internally.

An internally bonded portable generator is only to be used where it will not be connected to household wiring such as a construction site or camping.

To use your entire main electrical panel for generator power, an interlock kit installation may be a good choice for you.  See an example of an interlock kit that I installed on an older Cutler Hammer load center.

Not all of the materials shown in the above installation will be available at a home center or hardware store.  You will need to go to an electrical supply company where contractors go to get some of the parts.