Steel Building-Lighting Rods?

[Steven Hockstein]

One of my clients called me today and asked me if a steel barn needs to have lighting rods or is it acceptable to ground the building?

Answers?

[hausdok]

I guess I'd need to know if it's a pole barn with a steel skin or if it's an all-steel building solidly bolted to a foundation. If it were the latter, it would already be grounded, no? If it's a pole barn with a metal skin wouldn't it make sense to have a lightning rod system to ensure if it gets hit by lightning there is a clear path to ground?

I know, Steve; I didn't provide any answer. Hell, how long have you known me on this board? You know 'lectricity ain't by strong suit.

ONE TEAM - ONE FIGHT!!!

Mike

[Scottpat]

With lighting rods,isn't the goal to attract and then direct the lighting to the ground?

Growing up out in the hill country of TX we had poll barns that all had metal skins over wood frames with dirt floors. None of them had lighting rods. We had a few metal buildings on slabs that had electricity and plumbing, they did not have lighting rods either. I know that we had a few lighting strikes over the years and all it did was to punch a hole in the roof and short out the electrical. I have no idea if a lighting rod would have made any difference.

I'm afraid I would have to punt that question to an lighting rod expert, I'm sure we have them around.

[Bill Kibbel]

One of my clients called me today and asked me if a steel barn needs to have lighting rods or is it acceptable to ground the building?

Answers?

If it's just steel skin (roof and wall panels) on cold-rolled steel framing, it doesn't offer lightning protection. If the skeleton is made up of "metal bodies" 3/16" or thicker, it will conduct a direct strike to a grounding system.

http://www.oldhouseweb.com/how-to-advic ... tion.shtml

[kurt]

The last time I looked, which was a long time ago, there was no compelling evidence that conventional lightning rod systems didn't do anything in particular to route lightning away from a building, or to deter damage.

Are they really necessary anywhere?

[Bill Kibbel]

The last time I looked, which was a long time ago, there was no compelling evidence that conventional lightning rod systems didn't do anything in particular to route lightning away from a building, or to deter damage.

Are they really necessary anywhere?

More recent research shows they do protect buildings and property, when used as part of a complete lightning protection system.

[Steven Hockstein]

I was curious and called a local steel building rep and he was not in. I left a message wih his receptionist and asked if steel barns need to have lighting rods. I returned from a meeting to this message from him on my desk "We don't do that." WTF does that mean? Does it mean that someone else has to do it? Is it not needed at all?

I am just trying to get the answer as a favor but now I am wondering if this is something that is needed.

Bill, the described building is all steel so I am assuming all of the structure is steel framed. Does just adding lighting rods and grounding the structure equal a separate lighting grounding system?

I was hesitant to post this question because I thought maybe I should know the answer. Now I don't feel so bad!

Any sparkys reading this and want to answer?

[kurt]

More recent research shows they do protect buildings and property, when used as part of a complete lightning protection system.

Did they ever iron out the NFPA 780 and 781 issues?

At one time, it looked like the committee was largely made up of lightning rod mfg's. This is ancient, like maybe 10 years ago, but it's what I recall.

[kurt]

I've done the usual googling of the topic, and can't really come up with anything compelling. It's kind of like, they might work and they might not. Even Cecil Adams hedges.

The only certainty I've found is the mfg's. insisting they work and to think otherwise is obviously insane.

And, why would lightning hit a lightning rod and not the cast iron vent that's quite well grounded?

[tim5055]

I have a Morton Building in western North Carolina (future retirement/RV barn) and at no time did Morton, the engineer or the county building department talk about lightning suppression/rods.

As you can see, this one is all wood framing, bolted to a concrete foundation.

[Bill Kibbel]

I've done the usual googling of the topic, and can't really come up with anything compelling. It's kind of like, they might work and they might not. Even Cecil Adams hedges.

For one thing, the statistics studied by the insurance industry shows they reduce risk considerably.

And, why would lightning hit a lightning rod and not the cast iron vent that's quite well grounded?

A properly designed and installed lightning protection system provides a path to earth with the least resistance. Also, the shape and placement of the "air terminals", unlike plumbing vent stacks, is much more conducive to the release of ions called "streamers". When lightning occurs, paths of ionized air called "leaders" shoot toward the earth from the cloud. As the leaders near air terminals, streamers reach up and meet the leaders and the path is complete for the discharge to ground.

[Bill Kibbel]

I have a Morton Building in western North Carolina (future retirement/RV barn) and at no time did Morton, the engineer or the county building department talk about lightning suppression/rods.

As you can see, this one is all wood framing, bolted to a concrete foundation.

There's no requirement for a lightning protection system. It just reduces risk, and in some situations, insurance premiums. Put that building on a cleared working farm, fill it with expensive farming equipment, and it'd be stupid not to install protection.

[Bill Kibbel]

Bill, the described building is all steel so I am assuming all of the structure is steel framed. Does just adding lighting rods and grounding the structure equal a separate lighting grounding system?

Again, if the frame is made up of steel at least 3/16" it just needs bonding to a proper grounding electrode system. Ask the manufacturer of the building components to be sure.

[kurt]

"Members of the Scientific Committee of the International Conference on Lightning Protection has issued a joint statement stating their opposition to Early Streamer Emission technology." hmmmm.......

There's also the thing where it's been shown that lightning doesn't move in one direction; it's been shown that it can, and does often, move in two directions, mitigating the "streamer" effect or theory. Photographic studies have shown that the charge both emanates from clouds and is met by similar charges emanating from the Earth.

I am not saying they don't work, because I have no idea. But, I'm finding a lot of conflicting information, and little or nothing that indicates the science of lightning protection is firmly established, save the insurance statistics.

What's the thing where, if one believes, it's made real...(?). You know, like the feather Dumbo used so he could fly. What's the term for that?

[Marc]

Lightning rods are pointed for a reason. Electric charges tend to concentrate at sharp points and this attracts the opposite polarity charges in the sky more than the blunt cast iron plumbing vent. I forgot the name of this phenomena. Google 'skin effect'.

When they said that charges 'flow towards each other' they meant opposite polarity charges. One convention is to define lightning charges as existing in pairs, positive and negative. Similiar charges don't flow towards each other. Opposites attract. Other people, including myself, define lightning charge flow as the same as electron flow.

Marc

[kurt]

I read a study that indicated that's exactly what happens, and they meet somewhere in the "middle". They've got photos of it.

What I've gotten out of my reading is, no one is quite sure how lightning works. There's lots of opposing camps, all sure for sartin' that the other camp is wrong. One of the studies indicated "pointed rods" don't do anything in particular. The Faraday Cage phenomenon is agreed on, but that's about it.

I can't get away from the idea that there's some element of folks putting protection on a building, and when the building never gets damaged, claiming that as proof the equipment is "working".

[rjbrown2]

An object used for warding off undesired or bad consequences is called a talisman (formally) aka mojo, juju. gris gris, etc. Based on the conflicting information on the whole subject of lightning, said rods may have the mojo workin'

[Bill Kibbel]

"Members of the Scientific Committee of the International Conference on Lightning Protection has issued a joint statement stating their opposition to Early Streamer Emission technology." hmmmm.......

That's completely out of context and not about traditional lightning protection systems. When you Google, try reading more than one line that appears to support your unfounded criticism. Just like your post about NFPA 780/781"issues" you found a snippet, but didn't bother to read what it's about.

Early Streamer Emission technology was a theory that involved air terminal devices that looked like they were from a '50s science fiction movie. They supposedly released a stored ground charge and discharged an upward streamer earlier than any other object in the area.

The "conflicting information" you're finding is because it's about 2 different systems. One that works and has worked for 2 centuries and a recent theory that was dismissed after extensive testing and long-term studies under real lightning conditions.

[Douglas Hansen]

Franklin systems have propagated since 1752 because they work.

UL 96 provides listing for components of lightning protection system, and NFPA 780 provides installation guidelines. NFPA 780 is dealing essentially with passive lightning protection using the principles espoused by Franklin. Early streamer emission and dissipation array systems have been attempted and have no real record of success, whereas passive protection has worked for a long time.

Lightning is an alternating current that travels in steps, in both directions from earth to sky and back. The placement of air terminals per NFPA 780 is intended to provide an umbrella of protection. It uses a "rolling sphere" model for this, where air terminals on top of a building are of sufficient height such that a sphere with a 150 foot radius would roll over the terminals without touching the building. By placing them at those intervals, the "step" of the lightning strike would reach a terminal before it would reach the building structure.

While some aspects of lightning protection are understandable, there are also things like ball lightning that defy explanation. NFPA 780 has an interesting disclaimer: "Lightning is a stochastic, if not capricious, natural process. Its behavior is not yet completely understood. This standard is intended to provide requirements, within the limits of the current state of knowledge, for the installation of those lightning protection systems covered by the standard."

[kurt]

It has nothing to do with unfounded criticism and everything to do with finding contradictory information. And, why the **** do you think you know what I'm reading?

Even Hanson just went through an "explanation" and then finishes up with describing the recognized limits of understanding.

One of you says streamers work, the other says they don't. Compelling arguments.

Sheesh.

[Bill Kibbel]

One of you says streamers work, the other says they don't.

That statement makes it clear that you're still confusing Early Streamer Emission devices with traditional air terminals.

[kurt]

You didn't answer why the **** you think you know what I'm reading, and continue to choose "arguments" that are insults instead of providing links to science showing how lightning rods work.

You haven't, because I'm not sure you can. Read the disclaimer for NFPA 780.

Proclaiming something is true over and over until people believe it's true is political campaigning, not compelling argument.

[Steven Hockstein]

My question about lightning rods has really sent the sparks flying!!