For the full breakdown, see our best 10 AWG Copper Ground Wire guide.
A ground wire carries fault current back to the panel fast enough to trip the breaker. Undersize it and a short circuit can sit there heating metal instead of clearing. That is why the National Electrical Code sizes the equipment grounding conductor from the overcurrent device ahead of it — the breaker or fuse — and not from whatever is plugged in at the far end.
Two things decide nearly every residential job: the breaker’s rating and the metal the conductor is made of. The table below handles the first; the sections after it handle the second.
Is Ground Wire Sized By The Breaker Or The Load?
The equipment grounding conductor, or EGC, is sized from the rating or setting of the overcurrent device protecting the circuit. Load amps never enter the math. A 15-amp breaker feeding one LED lamp still gets a 14 AWG copper ground, because the breaker is what has to open during a fault.
NEC Table 250.122 sets those minimums, and it applies to the ground conductor that runs with the circuit in the same raceway, cable, or wiring method. Find your breaker or fuse rating, then read across to the copper size.
| Breaker Or Fuse Rating | Minimum Copper EGC | Typical Use |
|---|---|---|
| 15 A | 14 AWG | Lighting and general outlets |
| 20 A | 12 AWG | Kitchen, bath, laundry outlets |
| 30–60 A | 10 AWG | Dryers, ranges, subpanel feeders |
| 100 A | 8 AWG | Small subpanel feeder |
| 200 A | 6 AWG | Typical home service feeder |
| 300 A | 4 AWG | Multi-unit building feeders |
| 400 A | 3 AWG | Small commercial feeders |
| 500 A | 2 AWG | Commercial feeders |
| 600 A | 1 AWG | Commercial feeders |
| 800 A | 1/0 AWG | Large service feeders |
| 1000 A | 2/0 AWG | Large service feeders |
EE Power’s breakdown of the 2023 code narrows the residential side to four sizes: 14 AWG at 15 amps, 12 AWG at 20 amps, 10 AWG up through 60 amps, and 8 AWG up through 100 amps. Two fine points ride along with the table: a larger ground is always permitted, and the ground never has to be bigger than the circuit conductors it runs with.
Ratings above 1000 A keep climbing in the same table with the same logic; the rows shown cover nearly every residential and light commercial feeder you will run into.
Copper Ground Wire Size Chart: Three Mistakes That Fail Inspection
Most ground wire errors that get flagged trace back to one of three mix-ups: sizing from the load, sizing from the hot conductor, or treating a published chart as if it were the code text.
- Sizing to the load. An 18-amp appliance on a 30-amp breaker still needs a 10 AWG ground. The breaker sets the floor, not the appliance.
- Confusing the EGC with the grounding electrode conductor. The EGC runs with the circuit. The grounding electrode conductor ties the service to earth and is sized from the largest service or derived-system conductor under a different table — a split that Zoro’s ground wire size chart guide spells out.
- Matching the hot wire. At 15 and 20 amps the two often land on the same size, which makes “match the hot” feel like the rule. It is not. A 100-amp feeder can run 3 AWG conductors with only an 8 AWG copper ground.
Copper gives you the smallest conductor for a given breaker rating. Aluminum and copper-clad aluminum grounding conductors have to be larger than copper for the same rating, and the code carries separate rows for them.
That gap shows up when you buy. If you are stocking up, our tested 10 AWG copper ground wire picks lay the options out side by side.
Where The Published Chart Stops
Every chart you find online, including this one, is a summary of NEC Table 250.122 rather than the code text itself. Local amendments can change what your inspector expects, so the adopted code and your authority having jurisdiction have the final say.
NEC sizes do not transfer to other standards; a grounding table published elsewhere will not match this one. There is also a provision that requires the ground to be increased in proportion when circuit conductors are upsized for voltage drop, so a long run with oversized hots needs an oversized ground.
Ground conductors are safety-critical hardware. An undersized one can slow fault clearing and leave metal parts energized longer than they should be, which is the shock exposure the conductor exists to prevent.
Before you cut wire, work in this order:
- Read the breaker or fuse rating protecting the circuit.
- Look that rating up in NEC Table 250.122 and note the minimum copper size.
- Step up if you are using aluminum or upsizing conductors for voltage drop.
- Check local amendments before the inspector does.
FAQs
What Size Ground Wire Do I Need For A 20-Amp Circuit?
A 20-amp circuit needs a minimum 12 AWG copper equipment grounding conductor, straight from NEC Table 250.122. That holds whether the circuit feeds a bathroom receptacle, a garage outlet, or a single appliance that draws far less than 20 amps. The breaker’s rating is the number that counts, never the connected load.
Can The Ground Wire Be Larger Than The Table Requires?
