How do you design a lightning protection system for a building?

Lightning protection per NFPA 780 includes: air terminals (lightning rods) at roof peaks and edges with maximum spacing per building height, down conductors providing low-impedance path to ground, grounding system with ground rods or rings, and bonding of metal building components. The system intercepts lightning strikes and conducts energy safely to earth. Surge protective devices (SPDs) at service entrance and sensitive equipment protect against induced surges. Risk assessment determines level of protection required.