Which of the following is required for lightning protection ground rods?

The National Electrical Code (NEC) requires that all ground rods—whether for lightning protection, electrical service, or antennas—be bonded together to form a single, unified grounding system. This prevents hazardous voltage differences from developing between different grounded systems during a lightning strike, which could damage equipment or cause a fire. Connecting grounds to gas lines is incorrect and extremely dangerous. Furthermore, sharp right-angle bends in ground wires should be avoided because lightning seeks the path of least resistance and will often jump a sharp corner, leading to arc flashes.