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22  PM Engineer  December 2007

The Importance of 

Safety Standardsfor

Lightning ProtectionWithout the proper system in place,

lightning will produce heat, fires and even explosions.

By Kim Loehr

Lightning protection has come a long way since Ben Franklin first invented the light-ning rod in 1752. While the principlesbehind the science of lightning protec-tion remain the same, today’s structuresand their amenities have presented severalchallenges. Electricity, gas, indoor plumb-ing, telecommunication systems and irri-gation systems have created inductionproblems for modern structures, allowinglightning’s access into a structure throughenergized lines or system grounds.

The lightning protection safety stan-dards address protection for these func-

tions and systems, providing informa-tion and detailed installation proce-dures. These safety standards for instal-lation have been reviewed and revisedto not only address a building’s needsfor the structural lightning protectionsystem, but to also provide require-ments to protect the internal functionsof the building.

In other words, today’s lightning pro-tection systems provide practical andtested solutions for the interconnectionof grounded building systems, surgesuppression, requirements for commu-nication and data lines and coordinatedbonding. This adds up to a total packageprotection approach.

Recognized AuthoritiesWhen questions arise about light-

ning protection, it is important to know where to turn for accurate and up-to-date technical information. Whether thequestions arise on the drawing table oron the job site, there are three nationally recognized authorities that can be con-

sulted for technical information. Theseauthorities are:

• National Fire Protection Association(NFPA)—Standard for the Installation of Lightning Protection Systems, NFPA 780;

• Underwriters Laboratories (UL)—Installation Requirements for Light-ning Protection Systems, UL96A, andUL96, Standard for Lightning Protec-tion Components;

• Lightning Protection Institute(LPI)—Standard of Practice, LPI-175.

Of these three, NFPA 780 has the lon-gest history and is the most comprehen-

sive standard. The NFPA first adopted“Specifications for Protection of Build-ings Against Lightning in 1904.” Sinceits beginning, the NFPA Committee onLightning Protection has continued torevise and update the standard. The mostrecent edition was published in 2004.

In 1992, the numerical designationof the document was changed from78 to 780, and the name was changedfrom “Lightning Protection Code” to“Standard for the Installation of Light-ning Protection Systems.” At this time,NFPA 780 was accepted as an American

National Standard.UL has been testing equipment and

inspecting lightning protection systems inthe US since 1908. UL’s extensive group of field representatives are trained in light-ning protection to inspect sites includ-ing horse barns, missile silos, homes andhigh-rise buildings. UL has eliminatedthe previous use of a metal tag mount-ed to structures and changed to a papercertificate. A certificate of conformanceis issued to the owner through the UL-listed installing contractor for those proj-ects that comply with the UL96A safety standard. The UL96 component standardregulates manufacturers of products usedin lightning protection systems throughon-site factory inspections.

According to UL, “Lightning accountsfor more than one billion dollars annu-ally in structural damage to buildings inthe United States. What’s not reportedis the loss of business, downtime, andliability when business or commercialtenants are forced to shut down to repairlightning damage.”

 The most commonly employed grounding appli-

cation utilizes ground rods composed of copper,

copper-clad steel, hot-dipped galvanized steel or

stainless steel. These rods must extend vertically

at least 10 feet into the earth. (Photos courtesy of 

Lightning Protection Institute)

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24  PM Engineer  December 2007

While NFPA, UL and LPI are all not-for-profit organizations publishing safety information and installation standardsfor lightning protection, LPI is the only organization founded specifically to study lightning protection. LPI started promot-ing lightning protection education, aware-ness and safety in 1955. Its membership iscomprised of engineers, manufacturers,contractors, scientists, architects, and safety directors. LPI offers certification and edu-cation programming. The LPI’s “MasterInstaller” and “Certified System” programsqualify competence and quality control inthe lightning protection industry.

How the Network System ProtectsLightning is electricity. When elec-

tricity is confined to a properly designedconductive path, damage can be mini-mized. Destruction results when electric-ity encounters resistance, similar to theresistance used in arc welding. When elec-trical current runs through an arc welder,the resistance it encounters when arcingthrough air, generates the heat necessary to melt steel.

The highly conduct ive cop-per and aluminum materials used ina lightning protection system pro-

vide a low resistance path for light-ning to travel without resistance.When the lightning protection network is in place, a lightning strike is interceptedand directed to ground without impact toa structure or its contents.

Without the presence of the low-resistance path provided by a lightningprotection system (network), the light-ning will fight its way through non-con-ductive building materials like wood,brick, rubber membranes, glass, plastic,etc., on its way to the earth’s ground.The resistance the lightning encounterswill produce heat, fires and even explo-sions. It also is common for lightningto travel via conductive matter it findsalong the way, including plumbing, gut-ters, flashing, structural members and/or wiring for power, communicationor data.

None of these systems is designed toprovide a safe path to ground for light-ning. Providing this safe path to groundis the first focus of a lightning protectionsystem design.

Roof and Ground Network While the concept behind the light-ning protection is relatively simple, therequirements for proper installationare specific and often complex. Thesingle best way to ensure proper sys-tem design and installation is to speci-fy compliance with American NationalStandards Institute (ANSI) safety stan-dards for lightning protection (NFPA780, UL96, UL96A).

Strict compliance with the require-ments of these standards for the roof system, grounding and surge protec-tion are essential to proper system per-

formance. A lightning protection sys-tem includes the following elements:

• A network of prominent strike ter-mination devices;

• A network of ground termina-tions;

• A network of conductors or quali-fied structural steel members intercon-necting the strike and ground termina-tions;

• Interconnections with other metal-lic grounded building systems;

• Surge protection devices on allincoming power, data and communi-cation lines.

The first three elements of the sys-tem intercept, conduct and dissipatethe lightning discharge, while thefourth addresses the secondary effectsof a strike by limiting the dangers of the harmful current caused by sideflashing. The last element protectsconnected equipment and wiring fromdamaging currents and surges that cantravel on utility lines.

Specialized techniques are oftenneeded for specific applications, suchas connections across insulated joints,bonding, grounding strips, groundgrids and/or ground plates. Failureto make proper provisions for specialgrounding techniques, or for any of the above five elements can result ininadequate protection.

While it is true that lightning pro-tection is not a new concept, our mod-ern structures have prompted updatesand revisions to the safety standards toaddress problems with lightning enter-ing along energized lines or system

grounds. It is not enough to simply provide a lightning path for a struc-ture. Today’s lightning protection sys-tems must be designed to cover thecontents, equipment, operations andfunctions housed in a given facility.

It is this multi-step approach that ledto significant revisions in the 2004 Edi-tion of the NFPA 780 standard, underthe section covering surge protection(found under The  Protection of Ordi-nary Structures). Wording in the pre-vious NFPA editions was vague andunclear. The current standard now cov-ers installation information in detail,

while also providing the following:• Product requirements to achieve

acceptable levels of protection atentrances;

• Indications for additional needsfor internal equipment protection;

• Specifications regarding additionof grounds specific to surge protectiondevice installation for remote entrances.

Assessments of when and wherelightning protection is needed shouldultimately consider the basic principlesof lightning, risk assessment for thestructure and the fundamentals of theprotection system.

Kim Loehr is a marketing commu-nications consultant for the Lightning Protection Institute (LPI). The organi-zation conducts certification and educa-tional programs and serves as a resource for lightning protection information and system requirements. Visit www.light-ning.org  for more information or toaccess a list of certified contractors acrossthe United States.

Safety Standards for

Lighting Protection

Bonding of metallic bodies and roof compo-

nents to ensure continuity is a requirement of 

the lightning protection safety standards.