Tables › EGC Sizing
Equipment Grounding Conductor Sizing NEC 250.122
Minimum size equipment grounding conductor for each overcurrent device rating.
| Overcurrent Device Rating (Amps) | Copper EGC | Aluminum or Cu-Clad Al EGC |
|---|---|---|
| 15 | 14 AWG | 12 AWG |
| 20 | 12 AWG | 10 AWG |
| 30 | 10 AWG | 8 AWG |
| 40 | 10 AWG | 8 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 AWG | 2/0 AWG |
| 800 | 1/0 AWG | 3/0 AWG |
| 1000 | 2/0 AWG | 4/0 AWG |
| 1200 | 3/0 AWG | 250 kcmil |
| 1600 | 4/0 AWG | 350 kcmil |
| 2000 | 250 kcmil | 400 kcmil |
| 2500 | 350 kcmil | 600 kcmil |
| 3000 | 400 kcmil | 600 kcmil |
| 4000 | 500 kcmil | 800 kcmil |
| 5000 | 700 kcmil | 1200 kcmil |
| 6000 | 800 kcmil | 1200 kcmil |
250.122(B) — Upsizing Rule
When ungrounded conductors are increased in size for voltage drop, the equipment grounding conductor must be increased proportionally. Multiply the EGC size by the same ratio: (circular mils of actual conductor) ÷ (circular mils of minimum required conductor).
When ungrounded conductors are increased in size for voltage drop, the equipment grounding conductor must be increased proportionally. Multiply the EGC size by the same ratio: (circular mils of actual conductor) ÷ (circular mils of minimum required conductor).
Common Mistake
The EGC is sized based on the overcurrent device rating, not the wire size. A #10 wire on a 30A breaker requires a #10 copper EGC — but a #10 wire on a 20A breaker only requires a #12 copper EGC.
The EGC is sized based on the overcurrent device rating, not the wire size. A #10 wire on a 30A breaker requires a #10 copper EGC — but a #10 wire on a 20A breaker only requires a #12 copper EGC.
Conduit as EGC
Listed metallic raceways (EMT, IMC, RMC) can serve as the equipment grounding conductor per NEC 250.118. No separate EGC wire is required when using these raceways, though many electricians pull one anyway as a best practice.
Listed metallic raceways (EMT, IMC, RMC) can serve as the equipment grounding conductor per NEC 250.118. No separate EGC wire is required when using these raceways, though many electricians pull one anyway as a best practice.
For reference only. Verify all results with the current NEC and local amendments. See Terms of Use.