The Install

 Finally, the generator arrives: 

Essentially, the “install” has four functions: 1) Set generator on pad and bolt it down; 2) Mount transfer switch and connect service from electric meter; 3) Run wiring from transfer switch to the gen set and connect wiring to each; 4) Dig trench and run gas line from gas meter to gen set.

The challenge of the install is that these functions involve the skills of five different “trades”—design, landscaping, carpentry, electrical, and plumbing. In few cases, a generator “dealer” has sufficient interest, training and experience to cover all five.

In my case, I performed the design and landscaping as well as most of the carpentry work. 

It takes four men to carry the 500 pound gen set using bars that insert thru openings in the unit. Mounting the gen set to the pad was simple regarding the two 3/8-16x3/4 front bolts. The rear two were difficult because of tight space for tools, 

Mounting the large transfer switch required the installer to wrestle with the 4-0 SER entrance wire from the meter—a tough job even for two men. The entrance is connected to the transfer switch. Then another 4-0 SER is installed from transfer switch to the panel.  Mounting the transfer switch required a bit of simple carpentry work to add structure for attachment. Drywall needed to be removed for access, then reinstalled.

Wiring was run thru the attic space and down from the ceiling thru conduit. (3,3,3,5 Copper SER, 14-2 Romex and 18 ga shielded). Once thru the exterior wall, into a waterproof junction box where wiring was changed to meet code for exterior wire in conduit. Strain relief connectors anchor wires and cable in the j-box and openings in wall and box are sealed. The large #3 wires carry the house load. The 14-2 wires supply power to battery charger. The shielded wire run in separate conduit essentially is for control and communication between transfer switch and gen set. (Generac gensets require only one conduit) The exterior conduit is anchored to the AC unit’s concrete pad. Connections are made to the unit and the transfer switch. 

Interior wire penetrations thru foam board

Wire penetrations sealed from inside and vapor barrier patched 

Insulation reinstalled

Closet with access covers in place

Waterproof junction box-wiring adjacent to AC wiring and line set

The gas supply provided to the home is 2 psi. A regulator is placed in the gas line to the gen set reducing the pressure to 10” WC. The 1 1/4 poly gas line is run in the 18” deep trench and back filled. The connection to the gen set is made with a flexible line and everything is leak tested. The unit is then started and all functions set and checked.

The area where soil was placed temporarily during the trenching is raked and seeded. The backfilled trench has an inspection tube supplied for the Building Inspector. The backfilled area will be left alone for a time to allow settling before covering with mulch.

The total install, once all the previous “prep” work was done required about 30 man hours. Adding in the “prep” landscaping, carpentry and post clean up work, figure the whole job required about 50 man hours. 

Above are views of the installed unit. Final aspect involves notifying inspectors and having the final inspections completed.

Here is the message sent via email to the HOA Manager on 10/3/2023.

“As per our conversation on phone today, our 20KW Kohler Model RCA generator is installed.  Installation is in compliance with your guidance as well as meeting or exceeding all manufacturers instructions, the PA Building Code, the NEC, the NFPA, all aspects of the Declarations, the Rules/Regulations, and the PA Condominium Act. Specifically, wiring is adjacent to AC wiring and necessary wiring accessories are mounted as low as possible without endangering water line for exterior faucet and are 11” below the top of the generator—they are “shadowed” by both the AC unit and generator. There is no wiring conduit run along any exterior wall surface higher than 18” above the ground. No modifications to or drilling of any structural component. The thermal, moisture control and acoustic character of the building has not been diminished in any way. All wiring is copper. “

Border with mulch completed

The President of the HOA inspected and approved install on 10/4. Electrical Inspection completed OK on 10/12.

Conducted “power off” test using transfer switch disconnect. Noise levels as expected: About the same as a dishwasher (44.7 dB) inside bedroom; 63.3 dB at front of home outside—around the same as the volume from AC unit on patio.

Switchover was around 5-7 seconds (just enough to require digital clocks without battery backup to need reset) but switch back to utility power was instantaneous. 

During the test, noticed hot air from exhaust impacting the ground. I had figured that since the berm sloped down away from gen set that exhaust would not impact this ground area. Exhaust air exiting the unit is quite warm (300 F) and install manual warns to keep all flammable material clear for 3-4 feet, I installed non flammable paving stones on the berm to hold it and to keep vegetation from growing in the “hot zone”. 

Although air temp immediately leaving the unit is 300 F, ambient air mixes immediately and the air temp felt even 5 inches away is considerably less. Actual surface temp of the base edge while running is 115-125 F.  Interestingly, measuring surface temps 2-3 feet out are 80-90 F with a ground temp of 58 F. Temps at higher loads in summer will be higher.

On 10/18 at noon, the unit auto started and ran for 20 minutes as a test/exercise, as scheduled.