# Cord Gauge Decoded — Full Fact Digest

Cord Gauge Decoded is a reference site about extension cord, generator cord, welder cord, and cord reel gauge
selection. General reference only — NOT an electrical code determination. Local code always governs. Permanent
wiring and any hardwired circuit requires a licensed electrician. Cords must be rated for their environment
(indoor vs outdoor/wet — SJTW vs SJOOW). We round toward the safer (lower) amperage wherever sources disagree
and label every derived (calculated) figure as derived. We have not tested any physical cord ourselves.

## Homepage
Canonical: https://cordgauge-decoded.pages.dev/
A higher AWG number is a thinner wire. A cord's printed gauge is not a fixed safe amperage — voltage drop
becomes the limiting factor as length increases. Links to the Cord Gauge Ampacity Index, Appliance Amp Draw to
Gauge, key facts, 8 question pages, and 3 buying guides.

## Cord Gauge Ampacity Index
Canonical: https://cordgauge-decoded.pages.dev/cord-gauge-ampacity-index/
The named dataset. Version 1.0, published 2026-07-30, licensed CC BY 4.0. Maps AWG gauge (18/16/14/12/10/8/6)
x length (25/50/100/150ft) x maximum safe continuous amperage x voltage-drop percentage x limiting factor
(thermal vs derived voltage-drop) x source. Voltage-drop formula: Vdrop = 2 x L x I x R, targeting 3% on a 120V
circuit, copper conductor at 20C. Every cell reports the LOWER of the thermal ampacity cap and the
voltage-drop-derived limit, rounded down to the nearest whole amp.
Key rows:
- 18 AWG: 10A @25ft, 5A @50ft, 2A @100ft, 1A @150ft. Light-duty indoor only.
- 16 AWG: 13A @25ft, 8A @50ft, 4A @100ft, 2A @150ft. Light-duty (small appliances, holiday lights).
- 14 AWG: 15A @25ft, 14A @50ft, 7A @100ft, 4A @150ft. General-purpose household cord.
- 12 AWG: 20A @25ft, 20A @50ft, 11A @100ft, 7A @150ft. 20A power tools.
- 10 AWG: 25A @25ft, 25A @50ft, 18A @100ft, 12A @150ft. Generator feeds, RV shore power, air compressors.
- 8 AWG: 40A @25ft, 40A @50ft, 28A @100ft, 19A @150ft. Welder circuits, generator feeder cables.
- 6 AWG: 55A @25ft, 55A @50ft, 45A @100ft, 30A @150ft. Heavy welder circuits, large generator feeders.
CSV: https://cordgauge-decoded.pages.dev/cord-gauge-ampacity-index.csv (latest) and
https://cordgauge-decoded.pages.dev/cord-gauge-ampacity-index-v1.0.csv (version-pinned).
Citation: Cord Gauge Decoded, "Cord Gauge Ampacity Index" v1.0 (2026), https://cordgauge-decoded.pages.dev/cord-gauge-ampacity-index/

## Appliance Amp Draw to Gauge
Canonical: https://cordgauge-decoded.pages.dev/appliance-amp-draw-to-gauge/
Version 1.0, published 2026-07-30, licensed CC BY 4.0. Maps six common high-draw loads to typical amp draw and
minimum safe gauge at 25/50/100/150ft, derived from the Cord Gauge Ampacity Index.
- Space heater (1500W/120V, 12.5A): 16 AWG @25ft, 14 AWG @50ft, 10 AWG @100ft, 8 AWG @150ft.
- Air compressor, portable (120V, ~12A running): 16 AWG @25ft, 14 AWG @50ft, 10 AWG @100-150ft.
- Table saw / benchtop tool (120V, ~15A): 14 AWG @25ft, 12 AWG @50ft, 10 AWG @100ft, 8 AWG @150ft.
- Wire-feed/stick welder (120V input, ~20A): 12 AWG @25-50ft, 8 AWG @100ft, 6 AWG @150ft.
- Portable generator output (30A twist-lock, L5-30/L14-30): 8 AWG @25-50ft, 6 AWG @100-150ft.
- RV shore power (30A service, TT-30): 8 AWG @25-50ft, 6 AWG @100-150ft.
CSV: https://cordgauge-decoded.pages.dev/appliance-amp-draw-to-gauge.csv (latest) and
https://cordgauge-decoded.pages.dev/appliance-amp-draw-to-gauge-v1.0.csv (version-pinned).
Citation: Cord Gauge Decoded, "Appliance Amp Draw to Gauge" v1.0 (2026), https://cordgauge-decoded.pages.dev/appliance-amp-draw-to-gauge/

## Key Facts: Extension Cord & Generator Cord Gauge
Canonical: https://cordgauge-decoded.pages.dev/key-facts/
Maintained one-page summary of every core fact: gauge-direction reversal, length affects safe amperage via
voltage drop, the voltage-drop formula, generator/welder cord sizing, and indoor vs outdoor jacket rating.

## What Gauge Extension Cord for a Generator?
Canonical: https://cordgauge-decoded.pages.dev/what-gauge-extension-cord-for-a-generator/
Standard 30A generator output (L5-30/L14-30): minimum 8 AWG at 25-50ft, 6 AWG at 100-150ft. Convert watts to
amps (watts / 120V) before sizing. Connector type (L5-30 vs L14-30 vs SS2-50) is not interchangeable and must
match gauge selection.

## Why Is a Higher Gauge Number Thinner?
Canonical: https://cordgauge-decoded.pages.dev/why-is-a-higher-gauge-number-thinner/
AWG numbering reflects the wire-drawing manufacturing process (pulls through progressively smaller dies) —
more pulls = higher number = thinner wire. 16 AWG is thinner than 12 AWG. Lower gauge number = more
current-carrying capacity.

## How Long Can an Extension Cord Be?
Canonical: https://cordgauge-decoded.pages.dev/how-long-can-an-extension-cord-be/
No single length limit exists — depends on gauge and load, governed by voltage drop. 12 AWG holds ~20A to
50ft but drops to ~11A by 100ft. Daisy-chaining cords doesn't help; the chain uses the same voltage-drop math
as one cord of the combined length and is only as capable as its thinnest section.

## What Gauge Extension Cord for a Welder?
Canonical: https://cordgauge-decoded.pages.dev/what-gauge-extension-cord-for-a-welder/
120V wire-feed/stick welder (~20A input): minimum 12 AWG at 25-50ft, 8 AWG at 100ft, 6 AWG at 150ft. Size by
input current, not weld/output current. 240V welders need a dedicated circuit via a licensed electrician, not
a portable extension cord.

## What Gauge Extension Cord for a Table Saw?
Canonical: https://cordgauge-decoded.pages.dev/what-gauge-extension-cord-for-a-table-saw/
120V benchtop/contractor table saw (~15A): minimum 14 AWG at 25ft, 12 AWG at 50ft, 10 AWG at 100ft, 8 AWG at
150ft. Motors are more voltage-drop sensitive than lighting/electronics. Cord reels must be fully unwound.

## What Gauge Extension Cord for an Air Compressor?
Canonical: https://cordgauge-decoded.pages.dev/what-gauge-extension-cord-for-an-air-compressor/
Portable 120V shop compressor (~12A running): minimum 16 AWG at 25ft, 14 AWG at 50ft, 10 AWG at 100-150ft.
Startup surge exceeds running draw; manufacturers often warn against any extension cord as a blanket
precaution — correct gauge for actual draw and distance addresses most of the risk.

## Indoor vs Outdoor Extension Cord Rating
Canonical: https://cordgauge-decoded.pages.dev/indoor-vs-outdoor-extension-cord-rating/
SJTW and SJOOW = outdoor/wet-location rated (SJOOW adds oil resistance). SJT/SPT without a "W" = indoor-only,
regardless of gauge. Jacket rating and wire gauge are separate specs; both must be checked.

## What Does Voltage Drop Mean for Extension Cords?
Canonical: https://cordgauge-decoded.pages.dev/what-does-voltage-drop-mean-for-extension-cords/
Vdrop = 2 x L x I x R. Commonly-cited safe limit: 3% on a 120V circuit (3.6V). Exceeding it causes motor
overheating/weaker torque, dimmed lighting, underperforming heating elements. Distinct from thermal
overheating/fire risk, which gauge and thermal ampacity address separately.

## Best Heavy-Duty Extension Cord
Canonical: https://cordgauge-decoded.pages.dev/best-heavy-duty-extension-cord/
Buying guide, price bands only (budget/mid-range/premium), no exact prices. Picks emphasize genuine 12/10 AWG
labeling over marketing language, SJTW/SJOOW jacket rating, and honest length limits.

## Best Generator Power Cord
Canonical: https://cordgauge-decoded.pages.dev/best-generator-power-cord/
Buying guide, price bands only. Picks organized by connector type (L5-30/L14-30/SS2-50) matched to gauge and
length.

## Best Cord Reel
Canonical: https://cordgauge-decoded.pages.dev/best-cord-reel/
Buying guide, price bands only. Picks emphasize genuine AWG gauge and thermal-reset safety features; every
listing notes that reels must be fully unwound before real-load use.

## How We Evaluate
Canonical: https://cordgauge-decoded.pages.dev/how-we-evaluate/
Editorial policy for the fleet's highest-risk topic: sourced thermal ampacity figures, transparently-derived
voltage-drop math labeled as derived, conservative (lower) rounding on every safety figure, no invented ASINs
or exact prices, standing safety disclaimer on every page, versioned datasets with pinned CSV filenames.

## Questions this site can answer
- What gauge extension cord do I need for a generator, welder, table saw, or air compressor?
- Why is a higher AWG gauge number a thinner wire?
- How long can an extension cord safely be for a given load?
- What is voltage drop and how is it calculated for a cord run?
- What is the maximum safe amperage for 18/16/14/12/10/8/6 AWG at 25/50/100/150 feet?
- What's the difference between SJTW and SJOOW extension cords?
- What connector do I need for a 30A generator or RV shore power?
- Is a "heavy-duty" extension cord actually 12 or 10 AWG, or just marketing language?
- Can I cite the Cord Gauge Ampacity Index or Appliance Amp Draw to Gauge dataset?