22 kW Whole-Home Standby Generator and Automatic Transfer Switch

This Gresham home sits on a private well, which means a power outage doesn't just turn off the lights; it shuts off the water. The homeowners wanted backup power that starts itself, carries the whole house rather than a handful of chosen circuits, and keeps the well pump running through a multi-day winter outage. Power Professor designed and installed a complete 22 kW Honeywell standby generator system to do exactly that, with the transfer switch, the generator connections, and the new underground feeds all handled by one licensed crew.

The heart of the system is a Honeywell automatic transfer switch installed as the home's service disconnect. Because it is service-entrance rated, it sits between the utility service and the house panel, so every circuit in the home is backed up, including the heat pump condenser next to the generator. The switch watches utility power continuously; when PGE drops, it signals the generator to start, transfers the house to generator power within seconds, and transfers back and shuts the generator down once utility power has been stable again. Its factory-labeled emergency disconnect also gives first responders one clearly marked place to kill power to the house from outside.

The 22 kW air-cooled generator was set on its pad beside the heat pump with the manufacturer's clearances to the siding, the openings, and the condenser. We ran the generator's power conductors and the control circuit to the transfer switch in liquid-tight flexible conduit, installed the dedicated 120-volt circuit the unit needs for its battery charger, and coordinated the fuel connection with the gas contractor. Everything was load tested under a real transfer, and the weekly self-exercise schedule was set up with the homeowners during the walkthrough.

Feeding the pump house was the other half of the job. From a weatherproof outdoor breaker enclosure next to the transfer switch, a new feeder runs underground in conduit to the well house, where we set a dedicated subpanel and wired the submersible pump control box and the pressure switch at the Flexcon Flex2 Pro tank. Because the pump house is fed through the transfer switch, the well comes back on generator power automatically. Additional underground branch circuits for outdoor equipment leave from the exterior junction boxes on the same wall.

The homeowners had just finished the dark cedar siding and didn't want a wall of gray boxes and bare conduit next to it. Every riser, strap, junction box, and the breaker enclosure were painted to match the siding, the conduits were run plumb and aligned, and the penetrations were sealed. The result is a backup system that disappears into the house until the day it's needed.