Lightning protection

B

benfuest

New member
Dear American Arborist Collective.

While I do occasionally look at at some of the threads its been a while since I logged in to post. I've been in a forced retirement since 2011, sports injury. Rehabilitation has been focused on the physical but now, attempting to reduce the meds and re-boot the brain.

My request is a simple one, re conductor cable on lightning protection systems. For nearly ten years it has been common practice in the USA to employ a 14 strand 17 gauge conductor. I have in my memory recollections of anecdotal accounts of conductors over heating and scorching trees. Perhaps melting and or over heating soil around earth points resulting in disruption at grade.

Over hear we employ a slightly different method of measurement, cross section surface at 50 mm minimum, its a 32 strand.

Any recollections first hand, second hand or otherwise greatly appreciated.
Thank you
Ben Fuest
 
The ANSI Standard says
" 46.5.2.3 Conductors shall be at least 14 strand of 17 AWG copper wire."

at least. that is usually what is used. You could use 32 strand, but it costs more. And why spend/charge more money when less will meet the Standard? (not necessarily my attitude, because if the tree should require the maximum protection you can provide, why not use a higher capacity conductor?)

I have installed many LP systems and seen a few systems that had been hit and have not seen the overheating and scorching you mention. Not saying it couldn't happen.
 
Same as treegazer here. I sure don't recollect seeing any melted soil--that's the kind of thing that would stick in your brain! No scorching or worse yet bark popped off due to 14 strand use.

There are trees with fuses at Bartlett Labs and U of PA; you might ask them, I doubt they would say different. No, wait, there was one buttress root there that seemed to be damaged by sideflash, but that was attributed to not burying the conductor soon enough, (and inadequate length of fasteners). Far from fatal anyway. 32 strand seems like overkill by all accounts, though I wish the folks who dominate the ANSI process paid more attention, as you do, with earthing!
The standard just got revised, with very little change in anything but wording to be more in line with NFPA.
Nothing was allowed in on simple arboricultural practices to manage trees after a strike, but the quaint list of 'susceptible' species, the junkiest of science, stayed in there.
 
Thank you for your responses, I have some recollections from the dim past, but cant quite pin them down. I recall five systems at Bartlett lab three had taken hits , all three had issues. none fatal but issues non the less. Guy didnt you write an example of a system that over heated but the tree remained intact.
14 strand 17
 
.....Posted that before I finished!
14 strand 17 AWG is indeed what Ansi requires as a minimum. Looking back at the NFPA archive in 07 A submission for 14 strand 17 AWG was made and Rejected. In 2013 a second submission was made only this time for 16 strand 17 AWG. It was accepted in principle. I could be wrong but as far as I am aware theres no such thing.
When making a change to reduce the specification from 32 to 14 I think it fare to say thats dramatic, and if its sound then OK but please can we see the scientific pier review evidence to support it. Many of us in the lightning protection industry have looked for research papers articles or otherwise. Its a shame because with out the supporting evidence it will not get off the ground nay where else in the world.
 
A tree with LPS overheated but was intact? No recollection of that, nor any other issues that struck trees had at that lab. If NFPA approved 16 strand, what research did they go on? Maybe NFPA's the place for your search. Scott Cullen and Bill Graham cowrote the BMP; you might also ask them.

The change was before my brief time on the committee, and I don't remember the topic arising at the 2007 symposium.
 
The NFPA is where I started, the submission for 16 strand 17 AWG conductor was made by Dr Tom Smiley of Bartlett lab, the onus was on him to provide the supporting evidence for change. If we set aside the issue around does 16 strand 17 gauge exist and consider the claim made. "the new standard provides the same level of protection as the old" The old being 32 strand 17 AWG the new being 14 strand 17 AWG, less than half the size. There are of course many different varieties of lightning but if we in this instance restrict ourselves to classic cloud to ground, then it would be fare to say, it is pretty much the same the world over and trees are subject to the same, so what is it that has been discovered by the authors of the standard hitherto unknown. This new standard is unique in its specification and unique in its claim, I am not saying the claim is falls, but if true then the implications to the scientific lightning protection community around the world are not to be under estimated. The claim Also states that " the cost is cut from one third to half" As you can imagine very interesting to very many people. I have been asked to look at this and report on the science behind it, Unfortunately there would seem to be no empirical evidence in support of the standard and no pier review papers in the pipe line either.
Its a shame as if it were possible to produce a 14 strand 17 AWG with the performance of a 32 strand 17 AWG, then you could give up your day job. Many claims are made around the world on a daily basis, few are ever substantive and most are found to have less than admirable motive. To suggest reputations are at stake would be premature, I doubt those responsible would be so rash as to advance such a standard into a community before considering all the options and implications.
In the meantime I shall continue to look for the evidence to support the standard and its claims, should any one have any leads on published articles then I shall of course be greatfull.
 
So the NFPA did not ask for or receive ANY substantiation? Is that why they accepted the claim 'in principle', not 'in fact'?

Empirical evidence might be gained by sending a current through both and see how much jumps away from the conductor. But how much is too much depends on sensitivity of living tissue like cambium, and that's gotta vary widely; think redwood vs. beech. I think I'll try to market the installation of fuses during LPS checks. Many clients will pay extra to contribute to research. Do/did you add fuses to your installations?

Ben, re this 14 vs. 32 strand, I'm reminded of Arbor-Plex, the old standby climbing rope. Its strength was 5000 pounds. When safety standards were developed, the question of how strong is enough could not be precisely answered, so they just went by what was most commonly used, the 5000# of Arbor-Plex. So, after several revisions, 5000# remained the standard, out of habit, not science, is my understanding.

Ignorant of all this, I used to climb with a 3/8" sailing rope, ~3000#, tied to my bosun's seat (single-strap 'saddle'/belt) for 10+ years without incident (without much comfort, either...). now when weight restrictions impact traveling, I look at this heavy 5000#rope, and consider alternatives. But re the lightning standard I agree that claims should be verified. I imagine if anyone spoke up to the safety committee and claimed #3000 was strong enough, substantiation would be sought.
Did you ask Richard Roux, the NFPA liaison to A300?
 
"except the claim 'in principle', not in fact'
The NFPA have three responses to a submission, they are except, except in principle or reject. Thats it, nothing else.

Your methodology re your research suggestion is unclear, are you proposing sending current through the tree of the conductor or both? perhaps you could re think that one.

All our systems were fused.

14 vs 32. Look at it this way. Lightning kills people and costs billions of $ in insurance claims every year. There is only one recognised defence and that is the Franklin rod. The new standard takes the only defensive tool in the box and cuts it in half, while publicly stating it offers the same protection. That is either very bold or the work of genius. I have been asked to come out of retirement to look at it.

Consider the numbers, ANSI A300 PART 4 requires a minimum of 14 strand 17 AWG as opposed to the old A300 Part 4, 32 strand 17 AWG.
In 2007 the A300 committee made a submission to the NFPA 780 committee for the change to the 14 strand, it was rejected.
it is very time consuming and costly to make a submission, but the ANSI A300 committee, one presumes were keen to gain acceptance for there new specification. So in 2013 they tried again, only this time instead of submitting a proposal for 14 strand 17 AWG they submitted a proposal for 16 strand 17 AWG. On Monday morning ring Jan Yoder of the Independent Protection Company in Goshen, Indiana and ask for some.

So in short if you are using 14 strand you are working to A300 part for. But not the NFPA 780. because they gave acceptance in principle to 16 strand.

The above is just a side show to the feature which remains the absence of scientific research performed by are called on by the A300 part 4 committee.
I am not here to tell any one how its done or how to go about there research, I am here as requested to locate the research or reasoning behind the changes. You recently informed me you had installed over 100 of these systems and sit on the A300 committee as an observer, I assumed you would have all the up to date research and reasoning behind the standard.
 
Sorry Ben, I was attending meetings in 2013 and was in the lightning subgroup but do not recall that submission being reported to the subgroup or the committee. Sorry to disappoint you but 2007 was before my time on the committee. It may seem reasonable to assume the information would be public, but it is not. Despite ANSI principles of Openness and Transparency, a lot seems to happen behind the scenes.
Observers are no longer allowed to participate in A300 meetings, so I doubt I'll attend in October.

I won't ring Jan on Monday; it's a holiday. RR at NFPA should know why they accepted the submission only 'in principle'.
All I know is that a lot of textual changes were made to Part 4 to sync with NFPA, but few actual changes were allowed.
This is a lot more help than I can afford to give, in exchange for...nothing.

And no i won't be adding 2 strands to all those systems I installed, just to comply with NFPA!
The 32-strand systems I've seen look like a waste of copper. Like climbing with a 10,000# rope. Show me a 14-strand system that failed and I may well change my mind.
 
Standards committee meetings and there minutes are not published and thats just the way it is, I would not have asked for them. All I am doing is looking for the scientific reasoning published or otherwise behind the standard. if there is none then that is also the way it is, one would look for alternate motives for the change.

"this is a lot more help than I can afford to give, in exchange for...nothing"

The implication being if I gave you something, money perhaps, you would have more to say. Not sure that would be entirely proper, but thank you anyway. While you are unable to shed any light the science behind the standard you have at least provided your reasoning behind employing it.

"The 32 strand systems I've seen look like a waist of copper"

If that is what you believe then great that's an opinion from a sub committee member and Master Arborist with a hundred systems or more under his belt. It has value, so thank you for sharing that with us and enjoy your day off.
 
My reason for installing 14 strand instead of 32 is duty to client's interests, and maybe some monkey see monkey do aka following the standard, despite your questions. Alternative motives on their part may include the desire to protect more trees for less money.

Can you say 32 is needed, or is it just habit?

Implications...money hahaha nah way off Ben, I am out of the loop there, no longer a member, and as underinformed as can be. But I will ask my A300 reps about what was behind the change; you got me curious.
 
As I said in a previous post in the thread, if we confine your selves to traditional cloud to ground lightning then it matters not weather you are protecting an oil refinery, windmill, tree or whatever. They are all subject to the same laws of physics and when I said this new standard is unique in its specification, it is just that, unique.

The discipline of lightning protection and its associated studies have a history older than the study of trees. The new standard has adopted the principles of lightning protection without the knowledge of the fundamentals.

Imagine you have a 200 foot tall Douglas fir in a field and in the next field a 200 foot tall mast of some description. Both have a lightning protection system installed. The system in the tree has a conductor less than half the size of the one in the mast. Both the tree and the mast belong to the the same person, he says to you "They are both subject to the same phenomenon, yes" What do you say?
The question remains what is so different with the tree?

I am not here to tell you how to do it or tell you you are doing it wrong, yes I have opinions, thats why I have been asked to look at this. I have been asked to locate the science behind the standard and comment on that. Before I submit my findings I thought it interesting to ask the people that have been asked to work with this standard, do you no why trees are considered by the standard to be the exception and not subject to the same laws of physics?
 
Ben, if you and I stood under 2 identical trees, one with a 32-strand and the other 64-strand, and I told you the 32-strand offered equivalent protection to the 64-, would you agree?

Can you locate the science behind the 32-strand usage, and comment on that? You and I heard a lot of scientific presentations on lightning and trees in that symposium, did this topic even come up? The proceedings were on the ISA website for a while, but not now.

"The discipline of lightning protection and its associated studies have a history older than the study of trees." Where can I locate the science behind this electrifying claim? :oops:
"They are both subject to the same phenomenon, yes", where does that come in? This is getting hard to follow.
 
would I agree? no I would not.

The science behind the design and specification of conductors of goes back decades, if you really wanted to study it I would start with the works of Gold circa 1977.

Benjamin Franklin, 1749.

You have two structures same height, One is tree other is not. Other structure has conductor specifies to its standard, lets call it radio mast. The tree carries a conductor specific to A300. I
 
... they are both subject to the same laws of physics. the lightning that strikes trees is the same lightning that lands elsewhere. So why would the tree only require 14 strands? when 14 strands is not a recognised conductor for any land based lightning protection system. So the question remains the same. What is it that the ANSI standard believes that is unique to tree lightning protection and where is the research.

There is no point in asking for the evidence to support the use of 32 strand, it was what it was and worked. The ASNI has changed it, it is incumbent on the authors to provide the scientific evidence to justify it. If they cant then so be it, one would have to look elsewhere.

Thats all been typed very slowly for you.

Benjamin Franklin and before him the ancient Romans, Greeks and Egyptians. The Egyptians attempting to produce fulgurites as collected by Cleo Patra.

The topic of conductor specification was included in many conversations in 2007 and has done since. One of the most obvious example would be the amendment to the IPC web site offering both the new and the old, they have little confidence in the new.

As some one that has provided workshops, written articles, spoken at conference, sat as an observer on A300 and installed as you say over 100 lightning protection systems you really should be better informed with the science and service you provide.

I said I would not be critical or judgmental, I am just looking for the supporting evidence. But if I may make so bold as to suggest you discontinue with this particular service line, until such time as you have studied it and researched for you your self. It is as you said "duty to clients interests"

It has taken me 15 years of study and practical, it is not possible to do the subject justice on a forum in this add hoc manor. You no what you need to look for, apply our self and look.
 
"would I agree? no I would not." OK, then 64-strand would be better than 32. Would 128-strand be better than 64-strand?

Ben, trees were studied long before Cleopatra's time. The IPC website indicates a higher profit made on costlier material, not science. If I may make so bold as to suggest you discontinue with this inquiry, until such time as you can make statements that are reasonably defendable. (Not to be critical or judgmental of course) :D

One could say "There is no point in asking for the evidence to support the use of 14 strand, it is what it is and has worked for 7 years now." but I'm curious, so I have asked.

Best of luck with your endeavours.
 
The first officially recognized and published work on tree care was a book called Sylva it was first published sometime in the 1700's. A significant work, and the beginning of tree care as we no it today. It has been republished a few times and perhaps some one out there has a copy. It would be advisable to look and study the roots of the science and follow to today. It is the heritage and provides the underpinning knowledge of how we arrive at where we are today.

The same is said of lightning protection, in order to understand the science of today it is necessary to look back for the reasoning behind yesterday. Its not easy, it takes a long time and requires discipline. The net results of studying in the traditional manor may well seem outmoded and too time consuming in this day of instant info on line. This instant info on line is often incorrect, If you want to find an opinion to support your own you will probably find it. However this type of study lacks the all important guidance as provided by mentors that posses the history.

I could provide you with the mathematical formulae to equate the impedance and resistances of given conductors through a range of conditions, but it would be a meaningless mass of foreign language to you. So I attempted to provide simple examples in simple words, perhaps it is my fault for not being clear. But then you are not the only one reading this and maybe others have taken on board what has been said.

I'm not sure where you are going with the idea of continually doubling the size of conductor and asking me weather it would be better or not, I can only guess. You would need to look at the performance curve of the conductors and reason from there, but that perhaps is beyond your scope. However there is a very simple reason why one would not employ a 64 strand 17 AWG conductor in trees that perhaps you can grasp. I am confidant that there are a few viewing the post that can tell us, its not rocket science. In fact will some one please post the answer. Perhaps Treegazer, Treegazer sorry if your post appeared to be ignored, it was not. Your response was clear and considered, I believe you have installed systems and your clients interest is at the hart. Could you, being familiar with the 14 strand think why you would not work with 64 strand 17 AWG conductor and tell Guy.

The IPC web site does not indicate higher profits made on costlier materials. I have had many personal communications with IPC and one of the results of our communications was an amendment to the web site. The amendment was to set, side by side the two standards, old and new. Providing a choice for those that wanted the better of the two options. There is absolutely no reference or indication to profit made on either standard. However if you are looking for cost comparison between the old standard and the new I provide this. Its a quote, matter of public record from the lead architect of the new standard, Dr Tom Smiley.

"The new standard provides the same level of protection as the old standard but (at) about one-third to one-half the cost which means more people are willing to purchase lightning protection"

So you see, in the absence of any empirical scientific evidence in support of the change we look as I said for an alternative motive for change. I think we have it.

Thank you for wishing me well with my endeavour but it was completed last week, what was needed to complete it was an example of the ignorance and where better than here from you a Board Certified Master Arborist with over 40 years in the field. You have published articles on the subject, you have spoken at conferences on the subject, You claim to have installed over 100 systems and finally you sat as an observer on the ANSI committee.

I posted here confidant you would come to the surface and provide us with just such an example. Your words have exceeded expectation and the the transcription will provide a valuable insight into the mind set.
 
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