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Early Streamer Emission Air Terminal (ESEAT) Systems Fact vs Fiction

June 9, 2020

The cost of Lightning

1. Risk of Lightning Damage and disruption grows each year, costs growing at 20% per/yr, costs at $8 to $10 billion annually.

2. Application of a comprehensive Facility Lightning Protection System (FLPS) can eliminate and or mitigate these costs.

3. Much of this cost lies in the disruption and downtime of the facilities operations

4. Carnegie Mellon Survey concluded that 30% of US businesses will have a Lightning related failure or disruption yet only 10% of new buildings constructed in the US each year implement a Facility Protection System from Lightning related damage. (That’s something like 5.5* million businesses) If there are readily available technologies to prevent this growing dramatic threat why would we leave our industry so vulnerable?


Misperceptions about Facility Lightning Protection Systems

  • Ignorance – People, Owners, Engineers, simply aren’t aware of these available technologies and how they work and how effective they can be.
  • Regulation – In the US the implementation of a Facility Protection System, with one small exception in Florida, is completely up to the owner. They are not a requirement of the National Electrical or Building Codes.
  • Cost – Systems are perceived to be very expensive.
  • Complexity – Effective Facility Protection Systems are complex as they integrate with much of the facility.

1. Structural LPSs are the system most people think of when they think of Lightning Protection.  Air Terminals, Conductor, Downleads, etc.  all parts of a quality structural LPS.

  • US standards for these systems include NFPA 780 and UL 96A. Internationally these systems are covered by IEC-62305.


  • The UL Master Label Certificate program covers the inspection and Certifications of these systems.

2. The Cost and Complexity of these systems are a major factor for only 10% of new commercial buildings receiving a Lightning Protection System. There is an alternative system used widely throughout the world and used more extensively than recognized here in the US. These systems are ESEAT (Early Streamer Emission Air Terminal) Systems.



3. Since their introduction into the US in the 1990’s ESEAT Systems have been very controversial. Even the source of multiple lawsuits and countersuits throughout the industry. It’s the intent of this paper to provide the actual facts about ESEAT Systems, when and where they shouldn’t be used but also when and where they can be used to increase the number of protected facilities in the US.


Purpose of a Structural system

  • A structural LPS uses the basic physics of a lightning strike to generate a streamer that intercepts a downward leader from the storm cloud thus completing a circuit. Once the circuit is established the LPS conducts the current to the earth, bypassing the structure while equalizing the difference in potential between the cloud and the earth.  (See NOAA for more info on lightning formation)


Trees Being Struck by Lightning


1. This is how a conventional LP System works, each air terminal or strike termination device will generate a streamer in which to connect to the downward stepped leader. Just as seen in the picture of a forest of trees.



2. An ESEAT System provides a mechanism where the streamer is generated artificially, sooner thus extending well beyond traditional streamers, capturing the Downward leader.


History of ESEAT Systems

  • The engineer Pierre GRENIER, author of the first patent of a radioactive lightning rod in September 1931, observed that in southern France lightning strikes took place in cavities containing radioactive ores. Since these cavities were not located on high points, the only plausible explanation for this attachment of lightning appeared to be the result of ionization of the air created by the naturally radioactive ore.*1
  • The demonstration of this phenomenon is now possible thanks to the modern means of laboratory investigation which shows that the attachment of an electric arc takes place differently when the rod is or is not in an ionized medium. The picture below is an image recorded using a rotating camera: left photo the tip is not ionized and we can see that the arc does not start up continuously. As for the photo on the right, the tip is ionized: the electric arc starts continuously.*1

  • The engineer Pierre GRENIER created to exploit this patent the company Hélita in 1936 and subsequently the company Hélita filed patents improving the operation of these radioactive lightning rods in 1939 than in 1942.*1
  • The early streaming system described in this first patent was based on the use of radium beads arranged around the tip creating by their presence only permanent ionization of the air. Of course, at that time there was no question of measuring the time gain to the start of sparking which, as we know today, requires measuring devices with a resolution of less than microsecond.*1
  • For obvious reasons, The use of radioactive elements in the first active lightning rods with an early streaming system was authorized in France until the end of 1986. The decree of law of 22 July 1986 prohibits the use of radioactive elements in the manufacture of lightning rods.*1

1. In 1984, Hélita filed the patent for an early streamer lightning rod using an electronic circuit to ionize the air around the tip. The patent filed at the time was a joint patent between the company Hélita and the CNRS (National Center for Scientific Research). The advances in technology in those years made it possible to measure in a high-voltage laboratory the gains of a few microseconds brought by the early streaming device.*1

2. For a precise description of how an ESEAT head generates an early streamer see “The history of early streamer lightning conductors – by Bruno Roland” (xxx.xxxx)*1 But essentially the ESEAT systems uses the rise in the ambulant electrical field to charge the ESEAT circuitry, releasing a streamer significantly earlier than a passive strike termination device. This early streamer will be significantly higher into the atmosphere and will be drawn to the downward leader just as in the photo below.

3. This greater reach significantly increases the area of protection provided by the air terminal as compared with a passive rod.

4. The design of ESEAT Systems is governed by strict international standards most of which are based on the NFC 17-102 standard for the installation of ESEAT Systems. This standard just as the NFPA 780 and UL 96A dictate product quality, testing, zone of protection, potential equalization, grounding, and Surge Suppression requirements.

5. Today even UL recognizes the NFC Standard and UL Lists ESEAT heads to that standard.


ESEAT Use around the world

  • Today, by far the most widely used structural LP system in the world. Over 4.5 million ESEAT heads installed. Often in areas where the lightning frequency is the highest.


(Blue: Frequently used, Yellow: Sometimes used, Tan: Rarely used)

US Controversy & Poor Reputation

  • In 2000 the NFPA reviewed the current (or at least the provided) data on ESEAT systems and deemed that there isn’t ample basis in the scientific and technical literature for meaningful standards development activities for those systems. *2
  • This decision resulted in a lawsuit that would drag on for years essentially handcuffing the US industry from completing any meaningful research into or application of ESEAT systems.
  • Yet because there are no requirements for the LP systems in the US, many manufacturers offered, sold, and installed ESEAT systems in the US.
  • Because of no oversite, there were few if any standards applied to the US versions of these systems. One of the early adopters of these systems didn’t meet the most basic requirements laid out in the international ESEAT Standards.
  • Most ESEAT Systems installed in the US before 2010 do not meet the international ESEAT Systems. Thus, deserving their bad reputation.


ESEAT Systems today in the US

  • The systems do not meet the requirements of UL96A or NFPA 780 which are passive LP Standards.
  • Several manufacturers now offer NFC 17-102 compliant systems with UL listed ESEAT heads. The systems are fully backed by their multinational manufacturers with warranties and certifications and are eligible for a UL Engineering Inspection Report.

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1. Full Integration of both Structural and System Protection is the solution to nearly $10 billion of damage and disruption to US facilities each year. Increasing the application of these systems should be everyone’s goal.

2. Today’s facilities demand continuing operations, downtime is not acceptable. Lightning related disruptions and damage can be prevented with current technologies.

3. Using the multiple tools and systems available today, any operation or facility can be protected from the harmful effects of lightning strikes.