The Basis of Conventional Lightning Protection …

1 The Basis of Conventional Lightning Protection technology A review of the scientific development of Conventional Lightning Protection technologies and standards. Report of the Federal Interagency Lightning Protection User Group June 2001. Federal Interagency Lightning Protection User Group Participants: John M. Tobias, Chairperson, Federal Interagency Lightning Protection User Group Electronics Engineer Department of the Army, Communications Electronics Command ( Charles L. Wakefield Electrical Safety Team Leader Naval Ordnance Safety and Security Activity, Indian Head, Maryland Larry W Strother Electronics Engineer HQ Air Force Civil Engineer Support Agency Technical Support Directorate, Mechanical/Electrical Division Vladislav Mazur, Physicist National Oceanic and Atmospheric Administration, National Severe Storms Laboratory Department of Commerce Josephine Covino, Chairperson, Lightning Protection Working Group Department of Defense Explosives Safety Board John R.)

2 Fredlund Electrical Engineer National Nuclear Security Administration Department of Energy Hugh J. Christian, Jr., Senior Scientist Global Hydrology and Climate Center Marshall Space Flight Center National Aeronautics and Space Administration Monte Bateman, Thunderstorm Scientist (Contractor). Global Hydrology and Climate Center Marshall Space Flight Center National Aeronautics and Space Administration Warren K. Jordan Airway Operations Support (AOS). Federal Aviation Administration Department of Transportation Greg Heles Army Technical Center for Explosives Safety Department of the Army Table of Contents Section Page Introduction 1.

3 Notes on the Scope of this Report 1. Notes on the Federal Interagency Lightning Protection User 1. Group Development of Lightning Protection Science 2. Origins of Lightning Protection 3. Early Field Trials and Investigation of Failures - Purfleet 6. Origins of the Protected Zone Concept 7. Lightning Protection technology Matures Early Standards 9. Early Field Surveys Validating the Performance of Lightning 11. Protection Further Development of the Zone of Protection in Lightning 13. Protection Systems Recent Developments and Literature 15. National Lightning Detection Network (NLDN) 15.

4 Optimal Air Terminal Configurations 15. From Behind the Iron Curtain 16. Summary of Literature and Theoretical Results 17. Systems Analysis and Testing 18. Introduction 18. Laboratory Testing 18. System Level Field Testing and Evaluation 20. Insurance Company Experience 20. Reliability of Data 22. Iowa State Fire Marshal's Reports 24. Ontario Lightning Rod Act 26. Explosives Incidents Review 27. Kennedy Space Center Results 29. Federal Aviation Administration TDWR Study 30. Summary of Field Testing Results 30. Summary 34. Discussion 34. Conclusions 36. Recommendations 37.

5 Tables 38. Figures 41. Bibliography 52. Additional Reading 55. Introduction This report is a review of the body of literature, theoretical and empirical, that exists to substantiate the methods and practice of Lightning Protection as embodied in the current National Fire Protection Association's Standard 780, Standard for the Installation of Lightning Protection Systems. Development of this report is in direct response to the request embodied in the National Fire Protection Association's Standards Council Decision 00-30 for governmental users to participate in submission of technical substantiation regarding Lightning Protection systems.

6 Notes on the Scope of this Report We note that the primary emphasis of this effort is to demonstrate the science behind Lightning attachment to the strike terminations. We conclude that the effectiveness of down conductors, bonding techniques, grounding methods and practice are well established and need no further exposition. Development of existing Lightning Protection standards, in the as well as internationally derive from the same scientific sources. Although we focus on strike terminations (or air terminals) we find that the other components of the Lightning Protection system received equal attention in the demonstration of their effectiveness.

7 In this report, we will not address the various methods and practices proposed that deviate significantly from the so-called traditional or Conventional or Franklin Lightning Protection systems. We suffice to let those systems stand on their own merits as put forth in exhaustive studies published to date. Our focus and scope remains on what we find proven to be tried and true. Notes on the Federal Interagency Lightning Protection User Group The Federal Interagency Lightning Protection User Group originally started as an ad hoc committee of Department of Defense representatives to the NFPA Technical Committee on Lightning Protection (initially as part of an NFPA Task Force, since disbanded)

8 Assembled for the purpose of responding to the NFPA Standards Committee Decision 00-30, specifically the request for technical substantiation of the Lightning Protection techniques and practice contained in modern Lightning Protection standards. Since its original inception, it included representatives from Defense along with other Government agencies such as Department of Defense Explosives Safety Board, Federal Aviation Administration (Department of Transportation), Department of Energy, National Aeronautics and Space Administration, and Department of Commerce as well as advisors from industry and academia.

9 The Government activities participating in this effort contend that the precepts of Lightning Protection , as codified in NFPA 780 are valid, function to a high degree of effectiveness for the prevention of physical damage from Lightning and that these precepts serve as the underlying Basis for all of the Lightning Protection requirements specified by the Governmental departments. Although each department may issue specifications, standards or regulation to augment or detail Lightning Protection requirements, NFPA 780, Standard for the Installation of Lightning Protection Systems, remains as the basic document for specifying Lightning Protection .

10 The agencies represented use this standard extensively and further believe that action to cancel or weaken it would not be in the interest of the Federal Government, nor in the interest of the public good. Nor, as will be demonstrated by the following discourse, is cancellation or weakening in any way justified. Indeed, at the end of this discourse, it will be found that reinstatement of NFPA 780 to code status, as defined by the 2001 NFPA Directory1 is warranted by the weight of evidence available. Development of Lightning Protection Science The earliest developments in Lightning science and Lightning Protection begins in 1752 with Benjamin Franklin.