Lightning protection for site/roadway poles-what works?

mcutler

Member
I have a client with 40 - 35' poles on their site. Since this facility was built 2009 they have had 5 storms come through and cause significant damage to lamps, ballasts, and pole conductors. What can be done to increase isolation from lightning direct or indirect strikes?
 

cadpoint

Senior Member
Welcome to the Forum!

What are on the poles, what are all the poles used for, what's the circuit runs like, please describe all the equipment that's in service. Are these all metal or a "telephone pole"?

The only isolation thought for me is not to run metal conduit between poles, change to a lower pole use a lower profile lamp but be it a broadcaster of light!

How's the Area look in respects to 2012 ? :) It just seems that nothing been spared in this country or missing any weather as of late!

The NFPA 780 covers; Standard for the Installation of Lightning Protection Systems.

Good Luck! :)
 

mcutler

Member
Lightning protection for

Lightning protection for

What are on the poles-35' square metal, cutoff fixtures, what are all the poles used for-site lighting, what's the circuit runs like-20A/3P with 480V-2P lamps-circuits loaded to 10 amps in PVC, please describe all the equipment that's in service-500' to 1500' circuits with TVSS at building.
 

bphgravity

Senior Member
One option would be to install an overhead ground wire system between all the poles located on the property. This is sometimes referred to as a "faraday cage" or "catenary wire" lightning protection system. This can be seen at military installations and other hazardous occupancies.

Some guidance can be found in ANNEX G.1.2 of the NFPA 780. An example of this protection method can be found at FIGURE 7.3.3.2 of the NFPA 780.
 

kingpb

Senior Member
Ground rod at each pole connected to a rod at the top of the pole. That's the simplest. The effectiveness could be questionable depending on if the pole grounded through the base has a lower resistance than the ground wire to ground rod.

I suppose you could use shield masts and/or shield wires like in a substation, but that is probably not practical, and possibly not viable.

Could look into changing to concrete or fiberglass poles.
 

guggemos

Member
lightning protection

lightning protection

Usually the vendor supplying the pole sells lightning rod attachments for the top of the pole. There would be a ground wire run internally to the base of the pole and attached to a groundlug or plate. This in turn is connected to a ground rod.
 

weressl

Esteemed Member
Usually the vendor supplying the pole sells lightning rod attachments for the top of the pole. There would be a ground wire run internally to the base of the pole and attached to a groundlug or plate. This in turn is connected to a ground rod.
Seldom do these type of failures due to direct lightning strikes, but induced currents as the strike travels through the pole. The traditional lightning 'protectors' actually increase the strike potential as they attract the strike to be conducted through them by providing a low impedance path, thus the induced current damage could potentially increase.

We have found the highly controversial LEC systems to be an effective solution. We installed a comprehensive system over one of our largest plant that suffered 2-3 strikes and subsequent plant shutdowns. That happened 5 years ago and we experienced no shutdowns related to lightning strikes hence. The Waisala nationwide strike monitoring system actually indicated slightly increased strike density for some of the years in the area.

We also had similar experience with smaller installations, but those were not as well researched/documented after the fact, just the comment: "we no longer seem to have a problem with lighting."
 

bphgravity

Senior Member
The traditional lightning 'protectors' actually increase the strike potential as they attract the strike to be conducted through them by providing a low impedance path, thus the induced current damage could potentially increase.
Sorry, but this is a false statement. "Traditional" lightning protection systems do not attract nor prevent a strike from occuring. The presents of or lack of a LPS on a structure does not and can not indicate if a strike will occur at some point in the future. A properly installed LPS does not increase the potential for damage, but MAY help to mitigate or reduce any potential damaged.



We have found the highly controversial LEC systems to be an effective solution.
Any component of or method of installation of a LPS not recognized by the NFPA 780 or other nationally recognized lightning protection standard should not be considered, regardless of the claims made by the manufacturer and/or installers. Devices and equipment that are not listed to the ANSI/UL96A standard should also be discounted.

While I am not an authority on the LEC Dissipation Array System, I can assure you there are as many studies showing the ineffectiveness of these systems as there are claims that they actually do work. Any one considering a non-conventional system should first consult their insurance provider and research the system fully before committing.
 

weressl

Esteemed Member
Sorry, but this is a false statement. "Traditional" lightning protection systems do not attract nor prevent a strike from occuring. The presents of or lack of a LPS on a structure does not and can not indicate if a strike will occur at some point in the future. A properly installed LPS does not increase the potential for damage, but MAY help to mitigate or reduce any potential damaged.
Incorrect. Traditional lightning protection system DOES provide a low impedance 'attraction' point. That is the WHOLE purpose of it! The fundamental provision for a strike to occur is a low impedance path from the two charged objects - earth vs. cloud - and that is what the lightning rod provides compared to all other objects in the surrounding area. The charges are not stationary, but move along as the clouds blown by the wind. When the charges are high enough and the atmospheric discharge conditions optimal and a low impedance path is found, the strike occurs. So if a low impedance point is intentionally established that point will be more likely to be struck by lightning than others within a given area.




Any component of or method of installation of a LPS not recognized by the NFPA 780 or other nationally recognized lightning protection standard should not be considered, regardless of the claims made by the manufacturer and/or installers. Devices and equipment that are not listed to the ANSI/UL96A standard should also be discounted.

While I am not an authority on the LEC Dissipation Array System, I can assure you there are as many studies showing the ineffectiveness of these systems as there are claims that they actually do work. Any one considering a non-conventional system should first consult their insurance provider and research the system fully before committing.
LEC offered system is UL listed. I have shared my experience, that's all. I used to be a sceptic, but I find it hard to argue with facts and try to explain it away. Prof.(Emeritus) Moore of the Univ of Minessota, one of the foremost authority on lighting, had clearly acknowledged that while there is insufficient scientific understanding of what seems to occur with these systems, there is evidence that merits future work. So did Prof. Besleayan et al. None of the 'studies' that attempted to disprove the systems actually used the hardware, but conducted various statistical gymnastics. Studies need to be funded.
 

K8MHZ

Senior Member
Being a radio operator, lightning is a huge consideration among my ranks.

Here is how I was explained that dissipation, whether by simple placement of a tower or installation of some sort of dissipation system such as an array, works.

Lightning is an arc between two charge centers. We are concerned about strikes to the earth. Now, since a million volts isn't enough to travel over a mile on it's own, something else has to happen. That something is ionization.

Before any strike occurs, narrow arcs, actually spurs, form both in the cloud and from the earth. They are called feelers. You can see them in slow motion videos. The feelers, one from each charge center, are basically coronas that are in the process of ionizing the air. When one feeler meets up with another from an oppositely polarized charge center, a path of ionized air now exists from one charge center to the other. Ionized air conducts electricity really well, so now it's like we have a wire from one charge center to another and in the blink of an eye hundreds of thousands of amps travel through the ionized path.

The feelers are created from the most intense point of charge above the charge center. A charge center can occupy quite a bit of space, but only a tiny point will be the source of the corona that makes the feelers.

Dissipation is what we call the act of making adjustments to the design and adding devices to spread and even out the conductive area below the protected object so that the most intensely charged point above a charge center is moved outside the protected area.

Dissipation does not prevent lightning from striking. I minimizes the creation of feelers so that when the strike occurs, it occurs via a path outside the protected area.

It seems to work. If it didn't there wouldn't be so much testimony to that effect, which there is, but it is employed quite frequently in lightning protection.
 

K8MHZ

Senior Member
Ground rod at each pole connected to a rod at the top of the pole. That's the simplest. The effectiveness could be questionable depending on if the pole grounded through the base has a lower resistance than the ground wire to ground rod.

I suppose you could use shield masts and/or shield wires like in a substation, but that is probably not practical, and possibly not viable.

Could look into changing to concrete or fiberglass poles.
I have seen videos of a #6 solid conductor bonded to a ground rod serving a power pole vaporized by a strike of lightning.

A connection to earth with the intent of being a low impedance path for lightning to follow without fusing open won't be made of a small wire and it won't consist of one or even two rods pounded into the ground. It's a myth that a couple ground rods with a wire and a clamp will safely shunt a bolt of lighting to ground.
 

bphgravity

Senior Member
...So if a low impedance point is intentionally established that point will be more likely to be struck by lightning than others within a given area...
If that were true, a structure would be more protected without a LPS than with one installed. So would you suggest that a building with a LPS installed would be less likely to be struck if the LPS were removed and therefore less likley to be damaged from the effects of a direct lighnting strike.

This really doesn't make any sense.



LEC offered system is UL listed.
Yes, but only as a strike termination device (air terminal). They would still need to be installed (quantity and spacing) per the NFPA 780 and ANSI/UL96A. But they are not. The manufacturer gets the product listed but then says you only need one to protect an entire structure that would otherwise require 10+ terminals.

It's all a marketing ploy...


We will have to agree to disagree...
 

iwire

Moderator
Staff member
I think it is worth pointing out that while bphgravity claims not to be an expert here he is the only person I know that used some vacation days to visit a lightning research facility, he lives in the lightning capitol of the US (I think) and I bet he has study the subject far more than most.
 

weressl

Esteemed Member
If that were true, a structure would be more protected without a LPS than with one installed. So would you suggest that a building with a LPS installed would be less likely to be struck if the LPS were removed and therefore less likley to be damaged from the effects of a direct lighnting strike.

This really doesn't make any sense.
Of course things may APPEAR not to make sense IF taken out of context.

But, let me try to give you an example.

Say that there are some trees located nearby the said building, or any other structure of equivalent height, BUT a lower impedance level than what the building represents as a whole. In that case the likeliness of the strike terminating on the lower impedance points is greater than to terminate on the building.

As soon as you establish one or more lightning termination points on the building, the likeliness that the strikes will terminate on the new, lower impedance point - and not randomly on any point on the building - has increased. If the adjacent points would now fall UNDER the protective zone, then the likeliness of the strikes to terminate ON the termianls had greatly increased, but never 100%.

If anybody disputes that the traditional lighting protection is not a method of not only ATTRACTING but actually INDUCING lightning strike needs to go back and re-examine Ole Ben's experiment.
 

spikes2020

Member
I think it is worth pointing out that while bphgravity claims not to be an expert here he is the only person I know that used some vacation days to visit a lightning research facility, he lives in the lightning capitol of the US (I think) and I bet he has study the subject far more than most.

i would agree with this, if you want a full proof system you should get an expert. Lightning is not something you want to have a mistake with unless it's replaceable.

The guys i had quoted there also make a counter that counts the number of strikes on their device, we had about 10 in one year..... not too shabby.
 

bphgravity

Senior Member
Like I stated earlier, we will have to agree to disagree. And that is okay as this topic is extraordinarily controversial.

So instead of arguing the merits and limitations of conventional verses unconventional lightning protections systems, dropping a bunch of names of experts in the field, or citing research that makes one claim or another, let me just give my perspective as a code official for a local jurisdiction.

I can only enforce the legally adopted codes, standards, and local ordinances that govern lightning protection systems. And that is whether I agree with them or not or understand why or what the requirements they prescribe.

In the state of Florida, hospitals, nursing homes, educational facilities, and most other public buildings (EOC centers, government buildings, etc.) require lightning protection systems. These systems must be installed per the NFPA780 and ANSI/UL 96A. Section 1.1.3 of the NFPA 780 states, ?This document shall not cover lightning protection systems installation requirements for early streamer emission systems or charge dissipation systems.? I also know that both UL and the LPI will NOT certify (aka ?master label?) a nonconventional LPS unless it is installed and listed to the NFPA780 / LPI 175 / ANSI/UL 96A.

So it doesn?t matter what a manufacturer or installer of a nonconventional system claims if the systems are NOT legal. And it would be a disservice to install one of these systems (even if they work) if not in accordance with the law and nationally recognized standards.

So it is really not worth arguing over something that is really not aloud to be installed anyway. What would be the point? But I will make one last statement regarding a conventional system and its function. Again, I will simply reference the NFPA 780.

Annex B, section .3 in part states, ?Air terminals placed upon a structure do not substantially increase the probability of the structure being struck by lightning. If the downward progressing lightning leader is close to the structure, it will probably attach to that structure anyway. Thus, air terminals are designed to provide a preferential attachment point on structures that already provide a likely lightning attachment point. Once lightning connects to the air terminal, it is easier to control the lightning current and direct it to the earth, as opposed to it taking a random, uncontrolled (and usually damaging) path through the structure otherwise.?

So that is that?
 

Twoskinsoneman

Senior Member
Just wanted to say I really enjoyed reading through these post. It seems that in matters of lightening it is unlikely that the slight impedance changes we make with the protection system would make a significant effect on where the lightening will strike. (as if to say lightening would not have struck if the air terminal wasn't there). With the sheer magnitude of the forces involved I don't see how we could induce strikes by installing air terminals...
 

bphgravity

Senior Member
Look at it this way. Any and every earth-based object can and will be struck by lightning. This includes towers, buildings, trees, vehicles, mail boxes, people, animals, the open ground, and bodies of water. The list is endless. The event is so random and unpredictable that no model or math equation can be created that can predict or assume when, where, or how an object will be struck. People are struck by lightning standing next to buildings with a LPS. Tall building with robust LPS installations on the roof are struck on the side. Streamer emission paterns and charge dispersion of an earth-based object can not be used to indicate leader attachment.

The best that can be done is mitigation of a potential or realized strike. This is done using nationally recognized MINIMUM standards and manufacturer's recommendation that frequently exceed base standards.

The minimum code states that air terminals typically need to be installed at intervals not greater than 25 feet which will protect a zone roughly 30 degrees from vertical sometimes called the cone of protection. This method is derived from the rolling sphere model which is recognized by the NFPA 780.

ESE, CTS, DAA, and the other nonconventional systems typcially indicate a single device can protect up to 200 feet of linear roof surface and have cones of protection in access of 120 degrees from vertical. Many use the "collection volume method" or CVM model to establish this range of protection. And while it does appear the IEEE and other international organizations has accepted this model in whole or in part, the NFPA, UL, and LPI does NOT.

So like the NEC, why would anyone be comfortable or even consider an installation so below the minimum standard? The rsik associated with lightning is already high enough, isn't it?
 
Top