For a portable home generator, you want a heavy‑duty outdoor extension cord that matches the generator’s outlet type, amperage, and distance you need to run it.

Key safety rules

  • Use heavy‑duty outdoor cords labeled “SJTW” or “STW” and rated for generator use, not light indoor cords.
  • Match or exceed the amps of the generator outlet (often 20A, 30A, or 50A) and the voltage (usually 120V or 120/240V).
  • Longer runs need thicker wire (lower AWG number) to reduce voltage drop and overheating.

Recommended wire gauges

For most household situations during outages:

  • Up to about 25–50 ft:
    • 20A circuits → 12 AWG minimum, 10 AWG preferred for heavier loads.
* 30A generator outlet → **10 AWG** generator cord (NEMA L14‑30 if 120/240V).
  • Around 75–100 ft:
    • Use 10 AWG for 15–20A loads; thicker if you’re near the cord’s amp limit.

Never use 16 AWG or smaller (higher AWG number) for big loads like fridges, pumps, or multiple appliances from a generator.

Plug and outlet types

Check what outlet is on the generator:

  • Standard household (5‑15 or 5‑20): use heavy‑duty 12 AWG or 10 AWG outdoor cords with three‑prong grounding plugs.
  • Locking 30A (often L14‑30 120/240V): use a dedicated 30A generator extension cord with matching locking ends, usually 10 AWG.
  • Larger 50A outlet: use a 50A generator cord sized for that outlet (commonly 6–8 AWG depending on length and rating) and connect to a transfer switch/inlet, not directly into house wiring.

How many cords vs. one big cord

  • Safest is to run one generator cord to a transfer switch or inlet for the house when feasible, instead of many random extension cords.
  • If you must run cords directly to appliances, use separate heavy‑duty cords to big loads (fridge, freezer, sump pump, window AC) and avoid daisy‑chaining power strips or cheap multi‑taps.

Quick selector guide (HTML table)

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Generator outlet / load Typical cord type Wire gauge & length
Small tools / lights from 15–20A outlet Heavy-duty outdoor cord, 3-prong grounded 12 AWG up to ~50 ft; 10 AWG if longer or near max load
Fridge / freezer / sump pump Heavy- duty outdoor cord, 3-prong grounded 12 AWG preferred; 10 AWG if 50–100 ft
30A locking outlet (L14-30) Dedicated 30A generator cord, locking ends 10 AWG at 25–100 ft (check cord’s 30A/120–240V rating)
50A generator outlet 50A generator cord to inlet/transfer switch Heavy cable (often 6–8 AWG) sized per cord rating

Critical safety reminders

  • Keep the generator outside , away from doors and windows, to avoid deadly carbon monoxide buildup.
  • Do not backfeed a house by plugging a generator cord into a wall outlet; use a transfer switch or proper inlet installed to code.
  • Inspect cords for damage, soft spots, or loose plugs and replace anything questionable before use.

If you share your generator’s wattage, outlet types, and how far you need to run the cord, a model‑level recommendation can be tailored to your setup.

Information gathered from public forums or data available on the internet and portrayed here.