What is the 80% rule for generators?

The 80% rule for generators states that you should never run a generator above 80% of its rated running wattage continuously — so a generator rated at 10,500 running watts should carry no more than 8,400 watts of sustained load.

The reason is thermal headroom. Generators running at or near 100% capacity for extended periods build heat in the alternator windings and engine components faster than cooling can dissipate it, accelerating wear and risking automatic shutdown. Staying at 80% lets the generator handle sudden load additions — like a refrigerator compressor cycling on — without pushing the unit past its limits. On DuroStar dual-fuel models, apply the 80% rule to the fuel-adjusted output figure, not the gasoline peak spec.

• 80% rule cap on a DuroStar DS13000MX (10,500W running): 8,400 watts maximum sustained load.
• 80% rule cap on a DuroStar DS10000E (8,000W running): 6,400 watts maximum sustained load.
• Propane output on DuroStar dual-fuel models runs approximately 5% lower than gasoline output before applying the 80% cap.
• The 80% rule applies to running watts, not peak (starting) watts — those are a separate, brief surge allowance.