1,560 watts is the hard limit. I'd keep it under 1,200.

At 13 amps and 120 volts, the math says 1,560 watts max. But that’s the fuse rating, not a recommendation. Voltage drop over 50 feet means you’ll lose some power to heat, especially with cheap cords.

I’d treat 1,200 watts as the safe ceiling for continuous use. That covers a space heater on low, a circular saw, or a shop vac. Pushing it to 1,500 on a 50-foot cord? You’re asking the cord to work harder, which heats up connectors and can melt things over time.

If you need to run a 1,500-watt heater for hours, get a 12-gauge cord. The 14-gauge is fine for intermittent tools or lights. Don’t bet on the fuse saving you — it’s meant to prevent fire, not protect the cord from being annoying to use.