GUIDE
Electrical Wire Gauge Chart
House wiring sizes are standardized for a reason: 15/20/30 A circuits map to 14/12/10 AWG, and feeders step up from there. The chart lists branch sizes with full NEC columns.
Branch circuits and feeders (copper)
NEC 75 °C column; verify breaker sizing against NEC 240.4(D) limits.
| AWG | Diameter (mm) | Area (mm²) | Cu Ω/1000 ft | Typical amps |
|---|---|---|---|---|
| 2/0 | 9.27 | 67.43 | 0.078 | 175 |
| 1/0 | 8.25 | 53.48 | 0.098 | 150 |
| 1 | 7.35 | 42.41 | 0.124 | 130 |
| 2 | 6.54 | 33.63 | 0.156 | 115 |
| 3 | 5.83 | 26.67 | 0.197 | 100 |
| 4 | 5.19 | 21.15 | 0.248 | 85 |
| 6 | 4.12 | 13.30 | 0.395 | 65 |
| 8 | 3.26 | 8.37 | 0.628 | 50 |
| 10 | 2.59 | 5.26 | 0.999 | 35 |
| 12 | 2.05 | 3.31 | 1.588 | 25 |
| 14 | 1.63 | 2.08 | 2.525 | 20 |
The household ladder
North-American residential wiring follows a size ladder with almost no exceptions in branch circuits: 14 AWG = 15 A, 12 = 20 A, 10 = 30 A. Everything above those is appliance or feeder territory. Kitchens, bathrooms, garages and outdoor receptacles require 20 A; whole-house services move to feeders at 2/0–4/0 copper or aluminium equivalents.
Grounds, neutrals and derating still apply
The gauge chart answers only one of three sizing questions. Local ampacity also depends on insulation temperature column, conduit fill, ambient temperature, and continuous load at 125%. If your circuit has six current-carrying conductors in one raceway, the 75 °C column you select stops being 75 °C.
Aluminium branch circuits are a special era
1960s–70s homes wired with solid aluminium branch circuits require special connectors (Al/Cu at devices, antioxidant compound). Modern aluminium appears only in large feeders (2/0+) where its lightness and cost win. When you meet #12 solid aluminium, plan remediation rather than reuse.
Standard circuits and their wire sizes
House wiring reshuffles itself around a handful of circuits, and the wire sizes follow the breakers: 15 A lighting and bedroom receptacles → 14 AWG copper on a 15 A breaker; 20 A kitchen, bath and laundry receptacles → 12 AWG; 30 A water heaters, shop compressors and dryers → 10 AWG; 40 A heat pumps and small ovens → 8 AWG; 50 A ranges and RV pedestals → 8 AWG (or 6 AWG for margin); 60 A subpanels → 6 AWG copper (or 4 AWG Al); 100 A services → 4 AWG copper / 2 AWG aluminum; 200 A services → 4/0 copper / 250 kcmil Al. The wire gauge amp chart tabulates the same ladder from the National Electrical Code with all three insulation columns so nothing here is guesswork.
Voltage drop: the limit that hides in long runs
Ampacity protects wire; voltage drop protects the equipment at the end. The working target is a 3% drop on branch circuits (a 120 V line arriving at 116.4 V at the far end) and up to 5% total including feeders. At these voltages distance creeps up on circuits: a 100 ft 12 AWG bathroom circuit that passes every heat test still surrenders 4 V at load — lights that dim, compressors that short-cycle. Length forces sizes up in basements, shops and detached garages more often than current does; run the voltage-drop calculator before buying cable, then re-verify against the exact copper resistance column.
Aluminium, grounding and the fine print
Residential aluminium lives in the service world: entrance cables and big feeders get aluminium for cost and weight, with AL/CU-rated lugs and antioxidant paste at every termination. Grounding and bonding conductors size by their own table (250.122) — 6 AWG copper ground for a 50 A circuit, 4 AWG for 100 A services as the rule-of-thumb memory. Everything above the receptacles is inspector territory: wire fill in boxes, conductor derating in hot attics, AFCI/GFCI rules by room. Print the size on a real-size gauge chart when comparing jacket diameters at the supplier, and let the local code have the last word whenever a job touches mains.
Frequently asked questions
What gauge wire for household outlets?
12 AWG copper on a 20-amp breaker is the modern standard for kitchen, bathroom and washing-machine receptacles; legacy 15 A general outlets use 14 AWG.
What gauge wire for lighting circuits?
14 AWG copper on a 15-amp breaker covers standard lighting; long hall or outdoor runs over ~50 ft may use 12 AWG to hold voltage at the fixtures.
What size wire for a 50-amp range?
8 AWG copper (or 6 AWG aluminium) from a 50 A breaker, on a circuit wired for the range nameplate.
What gauge wire for a 60-amp subpanel?
6 AWG copper feeder (or 4 AWG aluminium) at 60 °C rating, keeping the subpanel neutral isolated from ground as four-wire code requires.
Can 14 AWG run on a 20-amp breaker?
No. NEC 240.4(D) protects 14 AWG at 15 A. A 20 A breaker on 14 AWG is an inspection failure and a fire risk.