• Gary Brandon - Lead Electrical Engineer, Duke Energy

Lightning protection standards exist for the protection of transmission and overhead distribution lines, as well as, switchyards but not for the protection of power generation facilities. In the absence of a specific lightning protection standard, lightning protection systems for power generation facilities in the United States are typically designed to the specifications of NFPA 780, “Standard for the Installation of Lightning Protection Systems”, even though that standard states that power generating facilities are excluded from its requirements. The requirements of the international standard for protection against lightning, IEC 62305, is applicable to all structures/buildings and relies on a rigorous lightning risk analysis study to determine the degree of protection required. In this presentation, a performance of a comparative analysis of the NFPA 780 and IEC 62305 standards demonstrates the IEC 62305 standard to be a superior lightning protection standard for the protection of U.S. power generation facilities. This analysis led to Duke Energy’s Fossil Hydro Operations Division’s decision to adopt the IEC 62305 as a basis for its own lightning protection standard.

The merits of a lightning protection system designed per IEC 62305 provides:

• A lightning protection system designed to protect against an actual lightning strike based on scientific research versus field experience alone.
• A lightning protection system that takes into consideration the structure/building it is protecting versus a “one size fits all” approach.
• A lightning protection system resulting from a rigorous, detailed lightning risk analysis study.
• A lightning protection system designed according to a four-tier lightning protection level system per a specified lightning impulse current.
• Surge protected devices tested to the internationally recognized 10/350 μs lightning current waveform.