Understanding surge (starting) wattage

Surge wattage, also known as starting wattage, is the short burst of additional power required to start electric motor-driven equipment. This extra demand typically lasts two to three seconds before the appliance settles back to its running wattage.

Portable generators are designed to accommodate this temporary demand by providing a brief, higher output. Understanding the difference between running and surge wattage helps ensure the generator is sized correctly for the intended loads.

Environment

Surge (starting) wattage applies primarily to portable generators. Air-cooled home standby generators are rated by maximum continuous output rather than a surge rating. Size a home standby generator so its continuous rating exceeds the total continuous load you intend to run.

Example power requirements

Appliance	Running watts	Surge (starting) watts
Refrigerator / Freezer	700 W	2,200 W
Clothes Dryer (Electric)	5,400 W	6,750 W

Appliances with motors (refrigerators, air conditioners, well pumps, etc.) briefly draw additional power when starting. Plan for this surge to avoid tripping breakers or overloading the generator.

Choosing the right generator

1. Add up the running wattage of all appliances you plan to operate at the same time.
2. Identify the highest surge wattage among those appliances and ensure your generator can supply that brief startup demand.
3. For home standby systems, size to continuous load needs, then consider managed load options if required. Use an in-home assessment or the sizing tools on Generac.com, or contact an Independent Authorized Service Dealer (IASD) via the dealer locator.
4. Confirm electrical requirements (volts and amps) for each appliance. If needed, look up your generator model on the product lookup page to find specifications and manuals.

See also

• Understanding portable generator power limits vs. advertised wattage
• What Does Running/Rated Wattage Mean?
• How many amps, volts, or watts do I need to run my appliance?
• How do I correctly size a generator for my home?
• Running your generator for extended periods during a major outage