Grounding, Bonding, and Surge Protection
Grounding and bonding questions test the difference between the two: grounding establishes a reference to earth, bonding connects metallic parts to equalize potential. Know Article 250 fundamentals, the grounding electrode system, equipment grounding conductors, and the requirement that communications and low voltage systems be bonded to the building grounding electrode system per Article 800 and TIA-607. Understand single-point grounding for telecommunications and why a separate isolated ground rod is a mistake-it creates potential differences.
Surge protection topics include surge protective devices at service, at panels, and at equipment; the difference between surge and transient; and the role of impedance and lead length. Traps: driving a separate ground rod for a rack, bonding at multiple points creating ground loops, and ignoring lead length on SPDs. Also watch for confusing grounded and grounding conductors.
Rule of thumb: bond, do not isolate-all grounding electrodes must be bonded together into one system.
Worked example: a rack with its own rod. Remove the isolated rod and bond the rack to the building electrode system with a properly sized conductor; add an SPD at the panel and at the equipment for layered protection.