Grounding Electrode Conductor
NEC 2020 — Table 250.66
| Largest ungrounded service-entrance conductor | Grounding electrode conductor | ||
|---|---|---|---|
| Copper | Aluminum or copper-clad aluminum | Copper | Aluminum or copper-clad aluminum |
| 2 AWG or smaller | 1/0 AWG or smaller | 8 AWG | 6 AWG |
| 1 or 1/0 AWG | 2/0 or 3/0 AWG | 6 AWG | 4 AWG |
| 2/0 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 1,100 kcmil | Over 900 through 1,750 kcmil | 2/0 AWG | 4/0 AWG |
| Over 1,100 kcmil | Over 1,750 kcmil | 3/0 AWG | 250 kcmil |
Minimum grounding electrode conductor size for AC systems, by the size of the largest ungrounded service-entrance conductor (or equivalent area for parallel conductors).
- Where the sole connection is to a rod, pipe, or plate electrode, the grounding electrode conductor need not be larger than 6 AWG copper or 4 AWG aluminum.
- Where the sole connection is to a concrete-encased electrode, the grounding electrode conductor need not be larger than 4 AWG copper.
- Where the sole connection is to a ground ring, the grounding electrode conductor need not be larger than the conductor used for the ground ring.
Source: NEC 2020 Table 250.66. Verify requirements against the locally adopted code and applicable amendments.