PEC Earthing
The conductor running from the earth bar to the physical ground rod has its own sizing logic, separate from the circuit protective conductor.
It's easy to conflate two different conductors that both get called "the earth wire" on site: the circuit protective (earth) conductor running alongside your circuit wiring, and the earth electrode conductor connecting your earthing system to the physical ground rod. They're sized by different logic.
| Conductor | Job | Sizing basis |
|---|---|---|
| Circuit protective conductor | Carries fault current back through the installation to clear a breaker | Keyed to the active conductor size it's paired with |
| Earth electrode conductor | Connects the earthing system to the physical ground electrode | Sized to handle the maximum fault current the electrode system might see, per its own table |
Using a circuit protective conductor-sized wire where an earth electrode conductor is actually required (or vice versa) is a real, recurring field mistake — the two serve genuinely different roles in the fault-clearing path, even though they're both colloquially "the earth wire."
Check both conductors separately using the PEC Earthing calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks