Diagnostic guide
How to Choose the Right Standby Generator Size in Puyallup
Last reviewed · Reviewed by the Pro Electrician technical team
Short answer
Most typical homes in Puyallup (2,000 to 2,800 sq ft) require a 18kW to 24kW automatic standby generator to power whole-house heat pumps, refrigeration, sump pumps, and lighting simultaneously. For essential-circuits-only backup, a 10kW to 14kW generator is sufficient.
Starting Wattage vs. Running Wattage
When sizing a generator, the most critical electrical factor is motor starting wattage. While a modern heat pump compressor might require 4,500 watts of continuous running power, starting up the stopped motor requires a brief instantaneous surge of 12,000 to 15,000 watts (LRA - Locked Rotor Amperage). Similarly, deep well pumps and refrigerators require high inrush currents. If your generator lacks sufficient surge kilowatt headroom, the engine will bog down, causing voltage sags that can damage delicate digital electronics.
- Starting inrush current on compressor motors is 2 to 3 times higher than running current
- Automatic transfer switches engage in under 10 seconds of utility power loss
- Whole-home units run directly on natural gas or on-site liquid propane storage tanks
Essential Circuits vs. Whole-House Coverage
Homeowners generally choose between essential circuit coverage and whole-house backup. Essential circuit setups (typically 10kW to 14kW) use a subpanel to power critical loads: furnace blower, refrigerator, internet router, medical equipment, and select lighting. Whole-house coverage (typically 18kW to 26kW) pairs with a 200-amp automatic transfer switch that connects between the utility meter and main panel, powering every outlet, light, and appliance in the home automatically.
Fuel Sources: Natural Gas vs. Liquid Propane
Automatic standby generators operate on your home’s existing pressurized natural gas utility line or an on-site liquid propane (LP) storage tank. Natural gas provides an endless fuel supply during extended blackouts, eliminating the need to store, transport, or pour gasoline in freezing rain. Standby units automatically perform a brief self-test exercise once a week to ensure mechanical readiness.
