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NEC Table 250.122 — EGC from overcurrent device rating
Select the breaker or fuse rating ahead of the equipment, choose copper or aluminum, and get the minimum EGC size. See the Equipment Grounding Conductor Guide for how EGC differs from the GEC and when upsizing is required. When size “should” pass but inspection or the fault path fails, use EGC Troubleshooting. Conceptual fork: Grounding vs Bonding Explained.
NEC Table 250.122 reference
| OCPD rating (A) | Copper EGC | Aluminum EGC |
|---|---|---|
| 15 or less | 14 AWG | 12 AWG |
| 20 | 12 AWG | 10 AWG |
| 60 | 10 AWG | 8 AWG |
| 100 | 8 AWG | 6 AWG |
| 200 | 6 AWG | 4 AWG |
| 300 | 4 AWG | 2 AWG |
| 400 | 3 AWG | 1 AWG |
| 500 | 2 AWG | 1/0 AWG |
| 600 | 1/0 AWG | 2/0 AWG |
| 800 | 2/0 AWG | 3/0 AWG |
| 1000 | 3/0 AWG | 4/0 AWG |
| 1200 | 4/0 AWG | 250 kcmil |
| 1600 | 250 kcmil | 400 kcmil |
| 2000 | 300 kcmil | 600 kcmil |
| 2500 | 350 kcmil | 750 kcmil |
| 3000 | 400 kcmil | 800 kcmil |
| 4000–6000 | 400–600 kcmil | 800–1500 kcmil |
Intermediate ratings use the next higher table row (e.g. 30 A or 50 A → 60 A row). For GEC sizing at the service, use Table 250.66 instead.
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Branch-circuit & grounding tools
Breakers, Romex, ground wire, and test gear for EGC work in panels and raceways.
Square D QO120 20A Breaker
- Table 250.122: 20A OCPD → 12 AWG Cu EGC
- QO plug-on design for load centers
- Common branch-circuit rating
- Verify label matches installed device
Southwire 14/2 NM-B Romex 250ft
- Includes 14 AWG bare copper EGC
- 15A circuits — minimum EGC per table
- UL listed indoor cable
- Match EGC to breaker, not just conductor
Southwire 10 AWG Stranded Copper Ground Wire
- Minimum EGC for 60A OCPD (Table 250.122)
- Pull in EMT or PVC when upsizing EGC
- Green or bare per local practice
- Common feeder and appliance circuits
Klein Tools ET310 Breaker Finder
- Identify which breaker feeds a circuit
- Confirm OCPD rating before EGC lookup
- Built-in GFCI outlet tester
- Essential before replacing EGC in live panels
Klein Tools 11047 Wire Stripper
- 10–18 AWG — typical EGC sizes
- Clean strip length for ground bars
- Made in USA
- Pair with torque specs on lugs
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What NEC Table 250.122 actually sizes
Table 250.122 sizes the equipment grounding conductor — the green or bare wire that runs with ungrounded and grounded conductors in cables and raceways. Its job is to bond metal equipment together and provide a low-impedance path for fault current back to the source so the overcurrent device can open. The table input is the rating or setting of the automatic overcurrent device ahead of the equipment, conduit, or cable — not the ampacity of the ungrounded conductors. A 60-amp breaker protecting #8 AWG conductors still requires a #10 copper EGC minimum, even though #8 alone might carry 40 or 50 amps depending on conditions.
EGC vs grounding electrode conductor — do not swap the tables
The grounding electrode conductor (GEC) connects the grounded service neutral to earth through electrodes and is sized from NEC Table 250.66 based on the largest ungrounded service-entrance conductor. The EGC is sized from Table 250.122 based on breaker or fuse rating. Think of the EGC as the emergency return lane that gets fault current back to the panel so the breaker trips — it does not need to reach a ground rod. The GEC is the separate wire that ties the system to earth for voltage stabilization. Using a fat ground wire to a rod does not satisfy branch-circuit EGC requirements, and sizing the green wire in a 60-amp feeder from Table 250.66 instead of 250.122 is a common plan-review error.
When the EGC must be larger than Table 250.122
NEC 250.122(B) requires the EGC to be increased in size when ungrounded conductors are upsized for voltage drop — the EGC must increase proportionally. If you bump a 12 AWG circuit to 10 AWG for voltage drop on a 20-amp breaker, the EGC stays at 12 AWG minimum from the table, but if conductor size increases further relative to the OCPD, apply the same proportional upsizing to the EGC. For parallel ungrounded conductors in the same raceway or cable, 250.122(F) requires combining the circular mil area of parallel EGCs; the calculator result is the minimum per conductor before parallel rules. Motor circuits, transformers, and tap rules may impose additional requirements beyond this table lookup.
Common EGC code violations
Using the bare wire size molded into Romex without checking the breaker rating fails when the OCPD is oversized relative to the conductor. Reusing a 14 AWG ground from old 15-amp wiring on a new 20-amp breaker violates the table. Running an isolated ground without a proper EGC path back to the source equipment leaves metal enclosures unbonded. At feeders, installing parallel phase conductors without parallel EGCs sized per 250.122(F) is a frequent commercial inspection hit. Substituting the water pipe or ground rod conductor for the circuit EGC confuses GEC and EGC roles entirely — see the GEC Sizing Guide for electrode conductor rules.