Generator House Connection


In 2004, two back to back hurricanes decimated our area.  No power for 18 days.  I was fortunate enough to have a motorhome at the time, and promptly evacuated.  I've since sold it, and bought a house.  While I will stay for a Category I or II storm, we will leave for anything worse.  Even a small storm can take power out for a while.  In 1995, Hurricane Erin was a Category I storm.  Knocked out power for 3 days here.  While my solar is great on sunny days, doesn't help much when the weather is bad.

Portions of my home are now powered with solar energy.  To be more accurate, solar panels recharge the battery bank, and an inverter converts the 12V to 120VAC in my home.  The battery bank is just large enough to run critical items for about two days.  After which, the batteries need to be recharged.  When the weather isn't sunny, and the grid is down, I rely on a Yamaha EF2400iS generator.  It sips fuel, and gets the job done.

Unlike a large 240VAC generator, I can't tie this directly into my house breaker panel.  This generator only supplies 120VAC.  Since my critical items now are being wired to operate from solar, it would be easy to connect to that setup.  To keep the two systems isolated, I added a transfer switch.  There will be another webpage dedicated to that project.




I've had this generator 9 years now.  Very quiet and reliable.

My generator doesn't have a twist lock type of power plug, so I'll have to modify that end.  I wanted a twist lock where it meets the house as the weight of the cord will try to unplug it.  Also note that I'm not making a "suicide" (male/male) power cord.  Those are dangerous, and likely to kill someone that might be seeking refuge at our house.  The jack on the house has a recessed male plug, tied to a transfer switch.  These pins are never hot.

I needed the wire to fall between the same wall studs as the transfer switch to simplify the wiring.  The location of the wall studs was verified, and a measurement to the door jam was taken.  The measurement was transferred to the outside wall, and a masonry bit was used to punch thru the wall.  Since my house is stick construction, easy drilling through the 1/4" stucco and foam board.  Also plenty of room inside the wall for the next steps.

To greatly simplify the job, I cut an opening in the drywall where the bit came thru.  I marked the box opening.

A drywall saw made short work of this.  While I had checked (with a AC wire detector) to make sure no power wires were in the wall, I was careful not to plunge the saw too deep... just in case.

The Reliance power inlet box was purchased on Amazon at this link. It's rated at 30A, and came with a flanged inlet plug already installed.  Unfortunately, this is the wrong plug for my setup, and the inlet box wasn't available without a plug, or with the specific one I needed.

I replaced the 30Amp flanged inlet plug with a L5-20P inlet plug.  My generator is rated for 20 Amps, so this plug is better suited for my application.  It was purchased on Amazon at this link.

With the new plug installed, ready to proceed.

The back plate was bolted to the wall, and the cable was lined up with the knockout.  Plenty of RTV was added to areas that penetrated the wall of the house.  Rain is a constant threat in FL... as are bugs.

Holes were drilled to mount the box with butterfly bolts.  Typically, a large hole would need to be made to get the bolts into the wall cavity, but since I had access to the inside, I made a hole just big enough for the bolts, and threaded the butterfly nuts by hand from the inside the wall cavity.


A slick feature of this box is that the cover and plug are mounted on a removable plate.  It would be difficult to tighten the wire clamp screws otherwise.


A view from underneath, with the box all complete.


A metal fish was fed from an upper access hole, down to the opening that was just made.  The wire was taped to the end of the fish, and pulled up.  Once it was inside the grey box, it was pushed the last few inches up to the transfer switch, which is not shown in this picture.

Since no terminations were made where the drywall was cut, I didn't need to put the cable into a box.  I got this nifty device at Home Depot.


Once it's put into the drywall opening, the screws are tightened, which causes two wing clamps to grab the backside of the drywall, and clamp it tightly.


A blank plate covers up the access hole.  Very easy to get back into it if needed later.


The power cord was another Amazon purchase, and can be found here.  My generator does have 20 Amp outlets, but they are not the twist lock type.  Consequently, I cut one off, and replaced the plug.

The 20 Amp male plug was purchased locally at Home Depot.  Unfortunately, most everything else I bought was not available there.

The final product.  Situated just outside of my garage, next to the battery box.

Ran a test tonight, all works as expected.  Check out the video below.  On to the next project....




Last updated 01/29/15    All rights reserved.