What Gauge Extension Cord for a Generator?
For a standard 30A generator twist-lock output, our Appliance Amp Draw → Gauge table calls for a minimum of 8 AWG at 25-50ft, stepping up to 6 AWG at 100-150ft. If your generator only feeds a standard 15-20A household-style outlet, 12 AWG is typically the floor at any of these lengths — but always confirm your specific unit's rated output first, and size up one gauge if unsure.
Convert watts to amps first
Generator ratings are usually printed in watts, but cord gauge is selected by amps. Divide rated wattage by 120V (standard outlet voltage) to get amps: a 3000W generator draws roughly 25A on a 120V circuit. Once you have amps, cross-reference the Cord Gauge Ampacity Index at your actual run length.
Why the bundled cord might not be enough
A generator's included cord is usually sized for a short run. If you need to reach further — into a house, a shed, or across a yard — you need a cord that is BOTH the right gauge for the distance AND fitted with the matching connector (L5-30, L14-30, SS2-50 — these are not interchangeable shapes).
This page is general reference, not an electrical code determination. Local code governs; a licensed electrician should handle any transfer-switch or permanent generator hookup.
Frequently Asked Questions
For a standard 30A generator output (the common L5-30 or L14-30 twist-lock receptacle), our Appliance Amp Draw to Gauge table calls for at minimum 8 AWG at 25-50ft, stepping up to 6 AWG at 100-150ft. For a smaller generator on a standard household 15-20A outlet, a 12 AWG cord is typically the floor at any of these lengths — check your specific generator's rated output first.
Not directly — you need amps, not watts. Divide the generator's rated wattage by its output voltage (120V for standard outlets) to get amps, then match that to the Cord Gauge Ampacity Index at your actual run length. A 3000W generator on a 120V circuit draws roughly 25A.
Only if it's long enough for your setup. Bundled generator cords are usually sized correctly for a SHORT run; if you need to reach further into a house or shed, buy a longer cord sized for that distance and load — not just any cord with a matching plug.
Yes. L5-30, L14-30, and SS2-50 are different locking connector shapes and are not interchangeable — the right gauge cord with the wrong connector simply won't plug in. Confirm your generator's exact receptacle before buying.