Ground Wire Sizing
Two different ground wires serve two different purposes. The equipment grounding conductor (EGC) runs with the circuit wires and bonds equipment to the fault path. The grounding electrode conductor (GEC) connects your panel to the ground rod.
Equipment Grounding Conductor (Table 250.122)
NEC Table 250.122 specifies EGC size by the maximum overcurrent protective device (OCP) rating. Breaker sizes between table rows use the next higher row.
| OCP Rating | Copper EGC | Aluminum EGC | Guide |
|---|---|---|---|
| 15A | 14 AWG | 12 AWG | Details |
| 20A | 12 AWG | 10 AWG | Details |
| 25A | 10 AWG | 8 AWG | Details |
| 30A | 10 AWG | 8 AWG | Details |
| 40A | 10 AWG | 8 AWG | Details |
| 50A | 10 AWG | 8 AWG | Details |
| 60A | 10 AWG | 8 AWG | Details |
| 70A | 8 AWG | 6 AWG | Details |
| 80A | 8 AWG | 6 AWG | Details |
| 90A | 8 AWG | 6 AWG | Details |
| 100A | 8 AWG | 6 AWG | Details |
| 125A | 6 AWG | 4 AWG | Details |
| 150A | 6 AWG | 4 AWG | Details |
| 175A | 6 AWG | 4 AWG | Details |
| 200A | 6 AWG | 4 AWG | Details |
| 300A | 4 AWG | 2 AWG | Details |
| 400A | 3 AWG | 1 AWG | Details |
| 500A | 2 AWG | 1/0 AWG | Details |
| 600A | 1 AWG | 2/0 AWG | Details |
| 800A | 1/0 AWG | 3/0 AWG | Details |
| 1000A | 2/0 AWG | 4/0 AWG | Details |
| 1200A | 3/0 AWG | 250 kcmil | Details |
| 1600A | 4/0 AWG | 350 kcmil | Details |
| 2000A | 250 kcmil | 400 kcmil | Details |
Grounding Electrode Conductor (Table 250.66)
| Largest Service Conductor (Cu) | Largest Service Conductor (Al) | GEC Copper | GEC Aluminum |
|---|---|---|---|
| 2 AWG or smaller | 1/0 AWG or smaller | 8 AWG | 6 AWG |
| 1 AWG or 1/0 AWG | 2/0 AWG or 3/0 AWG | 6 AWG | 4 AWG |
| 2/0 AWG or 3/0 AWG | 4/0 AWG or 250 kcmil | 4 AWG | 2 AWG |
| Over 3/0 through 350 kcmil | Over 250 through 500 kcmil | 2 AWG | 1/0 AWG |
| Over 350 through 600 kcmil | Over 500 through 900 kcmil | 1/0 AWG | 3/0 AWG |
| Over 600 through 1100 kcmil | Over 900 through 1750 kcmil | 2/0 AWG | 4/0 AWG |
| Over 1100 kcmil | Over 1750 kcmil | 3/0 AWG | 250 kcmil |
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Important: For reference only. Not a substitute for a licensed electrician. Electrical work can cause serious injury, death, fire, or property damage if performed incorrectly. Always hire a licensed electrician for electrical work, especially for service upgrades, panel work, and 240V circuits. Values are derived from NFPA 70 (NEC) for educational purposes. Always verify against your locally adopted NEC edition and amendments - local jurisdictions may enforce stricter requirements. WireRef provides reference information only and is not responsible for work performed based on this content. NEC® is a registered trademark of the National Fire Protection Association. Free NEC access via NFPA · OSHA Electrical Safety · Terms of use.
NEC 2023 references verified April 2026