Grounding at the Service: Electrodes, the Grounding Electrode Conductor, and the Main Bonding Jumper

"Electrical Grounding and Bonding" appears in the Services subject area on every Texas outline, and Article 250 is the most heavily tested single article after 210. This lesson is the service end of it: why we ground, which systems must be grounded, what counts as an electrode, how big the conductors are, and where the one grounded-to-ground connection lives.

1. The five things grounding and bonding must accomplish — 250.4

The performance rules the rest of the article serves:

1. System grounding — connect the system to earth to limit voltages from lightning, line surges and accidental contact with higher-voltage lines, and to stabilise voltage to earth.
2. Equipment grounding — connect enclosures to earth to limit voltage to ground on them.
3. Equipment bonding — connect enclosures together and to the supply source so an effective ground-fault current path exists.
4. Bonding of other conductive materials likely to become energised (piping, structural steel) — same reason.
5. Effective ground-fault current path — a low-impedance path that lets the OCPD open; able to carry the maximum fault current; and the earth shall not be considered an effective ground-fault current path.

That last sentence is the single most-tested idea in Article 250. Driving a ground rod does not clear a fault; the bonded metal path back to the source does.