NEC 250.122 equipment grounding conductor sizing
The NEC Table 250.122 minimum size of equipment grounding conductors, sized by the rating of the overcurrent device ahead of the circuit. Copper shown; aluminum upsizes.
Table 250.122 — EGC by OCPD rating (copper)
| OCPD rating | Copper EGC | Engine result |
|---|---|---|
| ≤ 15 A | 14 AWG | 14 AWG |
| ≤ 20 A | 12 AWG | 12 AWG |
| ≤ 60 A | 10 AWG | 10 AWG |
| ≤ 100 A | 8 AWG | 8 AWG |
| ≤ 200 A | 6 AWG | 6 AWG |
| ≤ 300 A | 4 AWG | 4 AWG |
| ≤ 400 A | 3 AWG | 3 AWG |
| ≤ 500 A | 2 AWG | 2 AWG |
| ≤ 600 A | 1 AWG | 1 AWG |
| ≤ 800 A | 1/0 | 1/0 |
| ≤ 1000 A | 2/0 | 2/0 |
| ≤ 1200 A | 3/0 | 3/0 |
The EGC is sized from the OCPD rating, not the circuit conductor — but per 250.122(A) it never has to be larger than the circuit conductors. When phase conductors are upsized for voltage drop, the EGC is upsized proportionally (250.122(B)).
Related: 250.66 grounding electrode conductor · 240.6 OCPD sizes.
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