NEC Grounding
Two similarly named NEC conductors with genuinely different roles, sizing tables, and purposes.
The Equipment Grounding Conductor (EGC) and the Grounding Electrode Conductor (GEC) have similar names and both relate to safety grounding — but they're genuinely different conductors with different jobs and different sizing tables.
Runs with the circuit conductors, bonding equipment enclosures and exposed metal parts back to the source — its job is providing a low-impedance path for fault current to trip the overcurrent device quickly. Sized per NEC Table 250.122, keyed to the circuit's overcurrent device rating.
Connects the grounded system conductor (or grounding bus) to the actual grounding electrode — a ground rod, concrete-encased electrode, or equivalent. Sized per Table 250.66, keyed to the size of the largest ungrounded (service) conductor.
| Conductor | Runs where | Sizing table | Keyed to |
|---|---|---|---|
| EGC | Alongside circuit conductors | Table 250.122 | Overcurrent device rating |
| GEC | System/service to electrode | Table 250.66 | Largest service conductor size |
Confusing which table applies to which conductor is a real, documented mistake — always confirm which specific conductor you're sizing before opening a table.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks