4. Earthing & Bonding for Protection · Page 1 of 6
Goals of an Earthing System
Safety, functional reference, and lightning current dissipation.
Three jobs
Earthing supports shock protection, provides a reference for electronics, and helps dissipate lightning energy. SPD performance depends on all three working together.
Low impedance at high frequency
Lightning is a high-frequency event. A "good" earth for 50 Hz faults may still be poor for surge currents if conductors are long and inductive.
Design mindset
Think equipotential first, resistance-to-remote-earth second for surge events inside a building.