Updating LightningProtection For Trees

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TCI Mag 06 04 FrontV5.qxp5/17/20043:15 PMPage 8Updating Lightning Protection for TreesBy Ariana ZiminskyMultiple cloud-to-cloud and cloud-to-ground lightning strikes caught using time-lapse photography during a nighttime thunderstorm. Courtesy of National Oceanic & AtmosphericAdministration Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL) .In August 2002, TCIA’s AccreditedStandards Committee A300 finalized adocument that redefined the way thosein the tree care industry deal with one ofnature’s most powerful facets – lightning.The new industry standard ANSI A300(Part 4) – 2002, Lightning ProtectionSystems incorporates significant researchin the field of atmospheric meteorology.This relatively new information has a profound impact on the requirements andrecommendations for all arborists who selltree lightning protection systems.Since there are an average of 25 millionstrikes of lightning from the cloud to1ground every year in the United States ,arborists who provide lightning protectionfor trees have their work cut out for them.Those who adhere to the ANSI A300 standards will be happy to find out that it isnow easier and less expensive to installsafe, effective lightning protection systemson valuable trees.8Who’s ANSI, andwhat is an ANSI standard?The American National StandardsInstitute (ANSI) is a private, non-profitorganization that administers and coordinates the U.S. voluntary standardizationClosing drive fastener: The conductor is installed startingnear the top of the tree. From this point downward theconductor is fastened to the tree with drive fasteners.TREE CARE INDUSTRY – JUNE 20042and conformity assessment system. ANSIaccredits organizations that aim to produceANSI standards, such as TCIA.ANSI standards are created by qualifiedindustry volunteers. TCIA’s ANSI-accredited standards committee (ASC) A300,formed June 28, 1991, set out to create several standards for tree care operationsbefore working down its checklist to thelightning protection standard. In 2000, theASC A300, which includes about 25 members and alternates, began to put togetherthe current requirements and recommendations for companies that install lightningprotection for trees.After gathering all the recent researchand writing up the draft, the committeepresented the standard to the public forinput. With all public comment taken intoaccount, the committee then created thefinal document, which was approved Aug.30, 2002.

TCI Mag 06 04 FrontV5.qxp5/17/20043:15 PMPage 9several years, however, studies have shownthat a blunt terminal works more effectively. Manufacturers are still catching up andhaven’t started producing blunt tips in anymeasurable amount.Compliance with ANSI A300 standardsis not mandatory, however adherence toANSI standards indicates a tree care company is making every attempt to follow thebest known tree care practices. ANSI A300standards provide the minimum performance parameters that arborists need to workwithin. They also are a guideline for writing work specifications.Dr. Tom Smiley, an arboriculturalresearcher at the Bartlett Tree ResearchLab, said that at Bartlett, tree care workerswho install lightning protection systemsare foregoing the sharp air terminals.The old standard vs. the new standardPrior to the publication of the ANSIA300 Lightning Protection Systems standard, the general industry guidelines wereoutlined in TCIA’s (formerly NAA’s)Lightning Protection Installation SystemsStandard, last revised in 1987.“The old . standard is really a lightningsystem for a house, put on a tree, withoutany additional research,” says Bob Rouse,TCIA’s director of accreditation who alsoserves as secretary of the ASC A300. “It’snot necessarily appropriate for a tree.”This now obsolete standard presented abrief description of how lightning functions; which types of trees are mostsusceptible to lightning; and when lightning protection systems should be used.In addition, it called for several very specific hardware recommendations foreffective systems. For example, the thickness of copper down conductors – “thevertical portion of a run of conductor“We’re switching to blunt terminals, butthere isn’t a manufacturer making themyet,” says Smiley. “So now we’re just cutting and bending wire” to simulate a bluntterminal. “It’s probably not quite as goodas a manufacturer’s blunt terminal,” hequips, “but we’re a little bit ahead of themanufacturers on this.”Additions to the new standardLightning damaged oak. Classic lightning damage showing a centerline of damage into the xylem, flanked bydamaged bark on either side. Unless otherwise noted, allpictures courtesy of Dr. E. Thomas Smiley.which ends at the ground” – was recommended to be “32 strands of 17 gaugecopper wire”; the placement of the grounding connections were suggested to be“beyond the dripline of the branches”; andthe points on the air terminals at the top ofthe down conductors were shown to besharp.Aside from several changes made fromthe old standard, there are also severalitems introduced in the new ANSI A300standard.Soil dependency: As stated in A300,“Soil type and the physical character of thesurrounding area shall be consideredbefore grounding the system.”“The new standard is very soil-dependent,” Smiley elaborates, “so you need toknow something about your soil depth andSome of the most significant changesfrom the old standard to the new guidelinesinvolve these very items. The new ANSIA300 standard calls for “14 strands of 17AWG copper wire” – not the 32-strandtype originally specified. New studies havehelped researchers conclude that groundrods need to be a minimum of 10 feet fromthe tree – with the actual distance depending upon the type of soil – but notnecessarily beyond the drip-line of the tree.Installing the ground in a trench.A third critical difference between theold and new standards is the “sharp-vs.blunt” air terminal tip debate. For decades,a pointed terminal on the end of a grounding wire was believed to be the bestmethod of lightning protection. In the pastTREE CARE INDUSTRY – JUNE 2004Driving the ground.9

TCI Mag 06 04 FrontV5.qxp5/17/20043:16 PMPage 10quality before you bid the job, or beforeyou put (the system) in.”is also an integral part of the new specifications.According to A300, if you are installingground rods in sandy soil, you need twicethe amount of rod that you would need ifthe soil were not sandy. Multiple groundsystems in typical soil require “a minimumof 8 feet of total ground rod length;” multiple ground systems in sandy or gravellysoil require “a minimum of 16 feet of totalground-rod length.”The old standard recommended dealingwith shallow soils only by using severalshorter grounding rods. The new standardoutlines a “horizontal ground system” inareas where rods cannot be driven morethan 2 feet into the ground. The typical horizontal system would be terminated with aground plate.Before this new standard, Smileyexplains, it didn’t make any differencewhat type of soil an arborist was dealingwith: one ground rod outside the drip-line,or “two to four multiple grounds . driven3as deep as possible,” was all that wascalled for – and in some cases, that mightnot provide proper protection.“It’s more likely under the old systemthat there would be damage to the trees,”Smiley adds. Under the new standard, henotes, “there still could be damage – but itwould be a pretty rare thing.”Ground plates: The introduction of theClosing the drive fastener: Drive fasteners are used tosecure the conductor to the tree. After it is driven intothe xylem, the crimp connector portion of the fastener isclosed over the conductor using either a large pair of pliers or as shown in this photograph, fence pliers.ground plate – “A copper plate used toform a ground terminal in shallow soils” –Protecting trees – not people, cars, buildings, boats, ammunition: “The singlebiggest thing in the new standard is that atree lightning protection system is onlydesigned to protect that tree,” Rouseemphasizes. “Arborists really need to put adisclaimer that lightning protection doesn’tprovide any personal protection or protection of any property.” A lightningprotection system on a tree will not protecta person, house, car – or anything elseunder the tree, he adds.This key point is stated clearly in theANSI A300 standard: “Lightning protection systems are used to reduce the risk ofdamage to trees from lightning strikes.Protected trees shall not be considered asafe haven from lightning strikes.”In contrast, the old standard somewhatimplied that a tree with a lightning protection system can offer shelter or safetyduring a thunderstorm:“Trees . with branches overhangingbuildings, . in a recreational or park area,particular trees under which children mightplay or people congregate during a lightning storm, isolated trees on a golf coursewhere golfers may seek shelter during arainstorm, isolated trees within a pastureunder which animals may gather during athunderstorm, . should be equipped withlightning protection systems set forth herein.”This dangerous and potentially fatalassumption that a lightning protection system on a tree could be a safe haven foranyone or anything underneath is a potentially fatal mistake to make.Please circle 12 on Reader Service Card10TREE CARE INDUSTRY – JUNE 2004

TCI Mag 06 04 FrontV5.qxp5/17/2004Major differencebetween the obsoleteNAA standard and thenew ANSI Standard:Prior to the current ANSI A300 LightningProtection Systems standard, the guidelinesfor protecting trees from lightning was outlined in TCIA’s (NAA) Lightning ProtectionInstallation Systems Standards. Theresearch incorporated into the new ANSIA300 standard includes several significantchanges:1.3:16 PMPage 12“Arborists need to write that disclaimerin their written specs and inform theirclients,” adds Rouse. “A tree lightning protection system is only designed to protectthe tree.”Distance between air terminals: Back inthe “old days,” it was concluded that, whenit came to air terminals connected to downconductors, more was merrier. The 1987standard encouraged “two down conductors . on any size tree,” and that trees withtrunks exceeding 3 feet diameter “shall beprovided with two, standard down conductors placed on opposite sides of the trunk.”THE NEW ANSI STANDARDLightning protection systems are used toreduce the risk of damage to trees fromlightning strikes. Protected trees shall notbe considered a safe haven from lightningstrikes.“On trees with broad heads,” it continued, “conductors [and attached airterminals] shall be extended into the highest parts of side branches in order to fullycover the spread of the crown.”THE OLD NAA STANDARD:Trees . with branches overhanging buildings, . in a recreational or park area,particular trees under which children mightplay or people congregate during a lightningstorm, isolated trees on a golf course wheregolfers may seek shelter during a rainstorm, isolated trees within a pasture underwhich animals may gather during a thunderstorm, . should be equipped with lightningprotection systems set forth herein."2.THE NEW ANSI STANDARDConductors shall be at least 14 strands of17 AWG copper wire.THE OLD NAA STANDARD:Copper consisting of 32 strands of 17 gaugecopper wire, . shall be used from the air terminal on top of he main trunk of the branch,down the trunk of the tree, to the groundingconnections. . Substandard (sic) diametercopper wire can be expected to vaporizeduring a lightning discharge of any magnitude, resulting in destruction or severe injuryto the supposedly protected tree.3.THE NEW ANSI STANDARDBranch conductors should be installed sothat no aerial portion of the tree is fartherthan 35 feed from a conductor.THE OLD NAA STANDARDFor additional protection, two down conductors can be used on any size tree. . Ontrees with broad heads, conductors shall beextended into the highest parts of sidebranches in order to fully cover the spreadof the crown.12These six blunt aluminum rods used in experiments by Dr.Charles Moore, et. al., show that blunt-tipped rods arebetter lightning receptors than sharp-tipped rods. Inthese experiments, done on South Baldy Peak, N.M., 13blunt-tipped rods were struck by lightning, but none ofthe nearby sharp-tipped rods took a strike. The two rodson the left were 12.7 mm in diameter, the rod on the rightwas 25.4 mm in diameter, and the other rods were 19mmin diameter. Source: The Case for Using Blunt-TippedLightning Rods as Strike Receptors, C.B. Moore, G.D.Aulich, and William Rison. Journal of Applied Meteorology,Volume 42, page 992.Not so anymore.“The new standard specifies that air terminals don’t need to be closer than 35 feet4to one another,” Smiley points out. “Thissaves a lot of money, because on a doublestem tree, under the old standard, youneeded two wires all the way to the top.Now, you only need one, and that is independent of tree diameter.”What the new standard means to youAccording to the National Oceanic andAtmospheric Association (NOAA), lightning causes about 5 billion of economic5impact in the United States each year. Forhomeowners, municipalities and otherswho previously could not afford a lightningprotection system, losing a valuable tree tolightning’s power could be devastating.Under the new ANSI A300 standard,however, tree lighting protection systemsare more affordable than those used in thepast.“The new standard provides the samelevel of protection as the old standard but(at) about one-third to one-half the cost –which means that more people are willingto purchase lightning protection, resultingin more trees being saved,” SmileyTREE CARE INDUSTRY – JUNE 2004explains.Dick Jones, of Davey Tree Experts,agrees: “The reduction in the size of thecable, the (reduction in the required) distance from the tree (and the) reducing ofthe materials . (all) reduce the cost of theinstallation.”“You might spend the same amount oftime installing the system, but the materialscost less,” Jones adds, meaning that ultimately, more people can afford to purchaselightning protection.How lightning and lightning rods workThe National Weather Service Office ofClimate, Weather, and Water Servicesoffers a brief explanation of how lightning6happens :A moving thunderstorm gathers (a) .pool of positively charged particles alongthe ground that travel with the storm. Asthe differences in charges continue toincrease, positively charged particles riseup taller objects such as trees, houses, andtelephone poles. .The negatively charged area in the storm

TCI Mag 06 04 FrontV5.qxp5/17/20043:16 PMPage 14Indeed, Franklin’s research into lightning has had a lasting influence in the fieldof meteorology. In 1750, Franklin speculated that “the emissions from sharp-tippedrods would prevent lightning by discharging electrified clouds.” In practice,however, he discovered that instead of discharging the clouds and preventinglightning strikes, the rods acted as a lightning receptor.will send out a charge toward the groundcalled a stepped leader. It is invisible to thehuman eye, and moves in steps in less thana second toward the ground. When it getsclose to the ground, it is attracted by allthese positively charged objects, and achannel develops. You see the electricaltransfer in this channel as lightning. Theremay be several return strokes of electricitywithin the established channel that you willsee as flickering lightning.This understanding of lightning has ledto thorough research regarding lightningrods.Dr. Charles Moore, a retired professor ofphysics at New Mexico Tech, has studiedthe best way to improve lightning rods thatare used in lightning protection systems.The conclusions drawn by him and othersemphasize that “using sharp lightning rodsis a mistake. They ionize the area aroundthem” – meaning that sharp rods create“electric field rates of intensificiation .much greater than those over similarlyexposed blunt rods for the initiation of7upward-going leaders” –or lightning.Thus, the sharp tips are, in effect, protecting themselves instead of dischargingelectricity from the storm. “Blunt rods,”according to Moore, “are better receptor(s)for lightning.”“With a blunt tip, electric forces getstrong enough because there is not that ionization occurring,” he adds. “Thus, theTo order a copy of the ANSIA300 Lightning ProtectionSystemsstandard,call1-800-733-2622 or order onlineat www.treecareindustry.org.electricity in the air can be more easily discharged,” resulting in a strike to the rod andnot the tree or other high points nearby.Although this recent breakthrough inunderstanding lightning has been incorporated into arboriculture in relatively recentyears, scientists have actually been studying the phenomenon for more than 2,000years. Few of us might recall that in 55 BCsomeone named Lucretius discovered that8lightning bolts prefer elevated objects, butmost of us can envision Benjamin Franklinoutside in a lighting storm with a key onhis kite string.Franklin’s discoveries regarding lightning – which he called a “most sudden andterrible mischief” – were held in highregard and for centuries were used as thebasis of lightning protection systems.Although the recent studies by Moore andothers have concluded that sharp-tippedrods are less ideal, it will take time beforethe new blunt-tipped-rod recommendationis commonplace.“We’re recommending that the NationalFire Protection Association specify theoptimum form for a lightning rod,” Mooresums up. “Right now, it’s still haunted bythe memory of Franklin’s suggestions.”Other research used in the ANSI A300standard came from studies done by thosewho are tree care specialists. “At theBartlett Tree Research lab, we have nearly100 (lightning protection) systemsinstalled that we monitor,” says Smiley.These trees have fuses on them, and whenthey are struck by lightning, researchersare able to observe any damage to the tree,wires and roots. “We draw conclusionsbased on damage and the system that is inplace,” Smiley adds.In addition, a lot of the new research usedin the standard comes from work done inFlorida, where a high count of lightningstrikes makes for an ideal testing area.“We learned a lot from sailboat lightningprotection,” Smiley explains. “They actually use a smaller wire on sailboats (thanwe use on trees)!”ConclusionPlease circle 14 on Reader Service Card14TREE CARE INDUSTRY – JUNE 2004With the thought in mind that at anygiven moment there are 1,800 thunder-

TCI Mag 06 04 FrontV5.qxp5/17/20043:16 PMstorms in progress somewhere on the earth,9adding up to 16 million storms every year,it’s little surprise that lightning protectionsystems are an important factor in savingtrees.Page 15Not yet ready to change with the times?The arborist uses ANSI A300 specs as a guide for writing work specifications. Your specs need tomeet the requirements and recommendations of ANSI A300. Beyond that there is nothing wrongwith over-specifying the system for those critical or high-end jobs. Over-specifying, with a reason,goes on in most industries – we are not an exception.Clearly, the new ANSI lightning protection standard is a huge boon to the tree careindustry. The new standard can make lightning protection a reality for homeownersand others who previously could not affordthe heavy-duty hardware that was part ofthe process. In addition, arborists andclients alike can rest assured that lightningprotection systems installed according tothe ANSI A300 standard have the bestchance of surviving a lightning strike.For the arborist, it is easy to get caught up in the actual “shoulds” and “shalls” of the standard.Don’t forget that anything over and beyond the standard is fine. The important thing is that theclient has a written spec to compare with others so they can make an informed decision. ANSI A300Part 4 allows the arborist flexibility so that the needs of individual trees and individual clients canbe met. A tree care company could even specify “deluxe” and “economy” lighting pr

The new industry standard ANSI A300 (Part 4) – 2002, Lightning Protection Systems incorporates significant research in the field of atmospheric meteorology. This relatively new information has a pro-found impact on the requirements and recommendations for all arborists who sell tree lightning protection systems. Since there are an average of 25 million strikes of lightning from the cloud to .

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