What is an Equipment Grounding Conductor (EGC)?
An EGC is the conductive path that bonds non-current-carrying metal parts to the source, sized per NEC 250.122 and qualified per NEC 250.118.
An equipment grounding conductor (EGC) is the conductive path that connects exposed non-current-carrying metallic parts of electrical equipment back to the source so that ground faults trip the overcurrent device quickly and safely. NEC Article 250 governs grounding and bonding, with NEC 250.118 listing what qualifies as an EGC and NEC 250.122 providing the sizing table. The EGC is one of the most misunderstood — and most critical — conductors in any electrical system.
What qualifies (NEC 250.118)
NEC 250.118 lists every conductor or raceway permitted to serve as an EGC. The complete list:
- A copper, aluminum, or copper-clad aluminum conductor (insulated, covered, or bare)
- Rigid metal conduit (RMC)
- Intermediate metal conduit (IMC)
- Electrical metallic tubing (EMT)
- Flexible metal conduit (FMC) — with limits: 6 ft and 20 A maximum
- Liquidtight flexible metal conduit (LFMC) — with similar limits
- Type AC armored cable
- Mineral-insulated metal-sheathed cable
- Type MC cable (with conditions on the armor type)
- The metal sheath of Type ALS, CS, MV, and Type MI cable
- Cable trays per Article 392.60
- Cablebus framework
- Other electrically continuous metal raceways and listed connections
Notable exclusions:
- PVC conduit (Schedule 40 and Schedule 80) — nonmetallic, no fault path
- ENT — also nonmetallic
- LFNC — nonmetallic
- All raceway with broken continuity or non-listed fittings
Sizing (NEC Table 250.122)
The EGC is sized by overcurrent device rating, not by phase conductor ampacity. Excerpt:
| OCPD rating (A) | Copper EGC | Aluminum EGC |
|---|---|---|
| 15 | 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 |
| 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 |
When phase conductors are upsized for voltage drop, the EGC must be upsized proportionally by area per NEC 250.122(B). This rule is frequently missed on long feeder runs.
EGC in conduit fill
EGCs do count toward conduit fill — they occupy space in the raceway just like any other conductor. Use the conduit fill calculator and include the EGC in your conductor count. The cross-sectional area for an insulated EGC (typically green THHN) comes from NEC Chapter 9 Table 5.
EGCs do not count as current-carrying conductors for ampacity derating per NEC 310.15(C)(1).
Common applications and code highlights
- Every branch circuit and feeder in metallic-raceway and nonmetallic-raceway systems
- Equipment bonding jumpers (NEC 250.102)
- Receptacle ground terminals (NEC 250.146)
- Motor frame bonding (NEC 250.110, 430.245)
- Parallel feeders — separate EGC required in each raceway, sized for the OCPD (NEC 250.122(F))
Bonding vs grounding — a quick clarification
- Grounding electrode conductor (GEC): connects the service neutral/grounded conductor to the earth (NEC 250.66)
- Equipment grounding conductor (EGC): connects equipment back to the source neutral
- Main bonding jumper (MBJ): bonds the EGC bus to the neutral bus at the service (NEC 250.28)
The EGC is the equipment fault path. The GEC is the earth reference. The MBJ ties them together — but only at the service or separately derived system.
Quick reference
- Article: NEC 250
- What qualifies: NEC 250.118
- How to size: NEC Table 250.122
- Counted in conduit fill: yes
- Counted as CCC for derating: no
- PVC, ENT, LFNC are not EGCs