Grounding Electrode Conductor
Size GEC per NEC Table 250.66 based on service conductor size.
NEC 250.66 Exceptions
| Electrode Type | Max Copper GEC | Max Aluminum GEC |
|---|---|---|
| Ground Rod (250.66(A)) | #6 | #4 |
| Concrete-Encased (250.66(B)) | #4 | #4 |
| Ground Ring (250.66(C)) | #4 | #4 |
These limits apply when the electrode is the sole connection. If multiple electrodes are bonded together, the largest electrode determines minimum GEC size.
Installation Requirements
- GEC must be protected if exposed (NEC 250.64(B))
- Aluminum GEC not permitted in contact with earth or concrete (250.64(A))
- GEC connections must be accessible (250.68(A))
- GEC must be unspliced unless using irreversible compression or exothermic welding (250.64(C))
NEC Table 250.66 - Grounding Electrode Conductor
| Size of Largest Service Conductor (AWG/kcmil) | Size of GEC (AWG/kcmil) | ||
|---|---|---|---|
| Copper | Aluminum | Copper | Aluminum |
| 2 or smaller | 1/0 or smaller | 8 | 6 |
| 1 or 1/0 | 2/0 or 3/0 | 6 | 4 |
| 2/0 or 3/0 | 4/0 or 250 | 4 | 2 |
| Over 3/0 thru 350 | Over 250 thru 500 | 2 | 1/0 |
| Over 350 thru 600 | Over 500 thru 900 | 1/0 | 3/0 |
| Over 600 thru 1100 | Over 900 thru 1750 | 2/0 | 4/0 |
| Over 1100 | Over 1750 | 3/0 | 250 kcmil |
Note: When service conductors are run in parallel in multiple raceways, the equivalent size is the sum of the circular mil areas. GEC may also be run in parallel to each service disconnect.