Air terminal

[quogueelectric]

I would like to know what the exact purpose of an air terminal is. I have my own theorys but want to see what is out there any takers?? There are a lot of smart people out there and like any theory it is all subject to interpretation.

 

[LarryFine]

I would like to know what the exact purpose of an air terminal is. I have my own theorys but want to see what is out there any takers?? There are a lot of smart people out there and like any theory it is all subject to interpretation.

Air terminal = lightning rod. Contrary to popular belief, the primary purpose is to minimize the liklihood of a lighning strike, and not to divert a strike.

The rods should have a sharp point, which helps stream electrons into the air, reducing the voltage across the space between the clouds and the earth.

"Discharging the capacitor" as it were.

 

[don_resqcapt19]

Larry,
Some area require the use of "safety" type air terminals that have a blunt end. There have been field tests that show no difference in the effectiveness of the blunt end terminals as compared to the traditional sharp tipped rods.
Don

 

[bphgravity]

An "air terminal" is a "strike termination device". It doesn't necessarily have to be a "lightning rod". Other materials and architectural features can be used as a strike termination device.

As a component of a Lightning Protection, an air terminal does not attract, divert, or serve to reduce the changes of a strike. It provides an intentional attachment point for lighting to terminate instead of other parts of the building or structure being protected.

In essence, if lightning strikes a building, the likelihood of the damaging effects being mitigated or reduced is increased by the installation of a LPS.

 

[quogueelectric]

air terminals

air terminals

I have installed hundreds of them and as you say they are brutaly sharp. Really dangerous to work with especially on a roof. I was taught that the air terminals actually cloak the building by making the ridge line an equipotential plane like a pool the same potential as the ground rods spiked into the earth. The electrons flow although slowly because air is a poor conductor yet they do flow slowly. This phenomenon is so that as a lightning cloud is passing by it looks at the building as an unatractive target the same potential as a groundrod 8 feet below grade. I just wanted to check with the experts so that I can keep believing in this theory.

 

[bphgravity]

No. The theory you describe is not accurate.

Lightning Protection does not cause nor can prevent a structure from being struck by lightning.

All earth-based objects emit streamers when the air is electrified from an approaching storm. When the charge separation occurring within a cloud reaches a critical point, a stepped leader(s) is emitted from the cloud towards the earth. If you, a tree, or your building just happens to be the earth based object in which the connection is made, the stroke occurs.

If your building happens to have a LPS, the stroke attachment is more likely to occur at the strike termination device which has an intentional low impedance path to earth. If your building does not have a LPS, the stroke attachment may occur anywhere on the structure and cause destructive currents to flow over high-resistance paths. In either case, neither building is any more likely or any less likely to be struck.

 

[quogueelectric]

air terminal

air terminal

No. The theory you describe is not accurate.

Lightning Protection does not cause nor can prevent a structure from being struck by lightning.

All earth-based objects emit streamers when the air is electrified from an approaching storm. When the charge separation occurring within a cloud reaches a critical point, a stepped leader(s) is emitted from the cloud towards the earth. If you, a tree, or your building just happens to be the earth based object in which the connection is made, the stroke occurs.

If your building happens to have a LPS, the stroke attachment is more likely to occur at the strike termination device which has an intentional low impedance path to earth. If your building does not have a LPS, the stroke attachment may occur anywhere on the structure and cause destructive currents to flow over high-resistance paths. In either case, neither building is any more likely or any less likely to be struck.

Is this the theory which Heary Bros had to go to court over??

 

[quogueelectric]

air terminals

air terminals

Larry,
Some area require the use of "safety" type air terminals that have a blunt end. There have been field tests that show no difference in the effectiveness of the blunt end terminals as compared to the traditional sharp tipped rods.
Don

I would always screw blue/grey wirenuts over the points so I didnt get impailed on those darned things. I would take them off at final install because insulating the air terminal is not a good thing either.

 

[iwire]

Is this the theory which Heary Bros had to go to court over??

Heary Bros

 

[bphgravity]

Is this the theory which Heary Bros had to go to court over??

No. The lawsuit they were apart of was in regard to ESE or Early Streamer Emmission claims.

To date, there is no evidence that any "enhanced" lightning protection system exists which provides superior protection to a "conventional" LPS as recognized by the NFPA 780, LPI, or NLSI.

 

[charlie tuna]

in the systems i have installed the air terminals can be heard arcing when a thunderstorm is close by. they bleed the charge to neuturalize the potential difference between the building and the charges in the air...

 

[quogueelectric]

heary bros

heary bros

No. The lawsuit they were apart of was in regard to ESE or Early Streamer Emmission claims.

To date, there is no evidence that any "enhanced" lightning protection system exists which provides superior protection to a "conventional" LPS as recognized by the NFPA 780, LPI, or NLSI.

I am trying to figure out where I read or learned this theory it was either a discovery channel or instalation instructions on one of the systems I have installed. I do not remember where most of the installations I have done was Heary Brothers I do remember doing some systems other than heary bros but I dont remember thier names. It could have been a company rep on the phone explaining instalation instructions or a company rep who came out to inspect the instalation and sign off on the install done compliant to thier spacific instructions. I have always been intrigued by lightning and will further track down more information on the subject . Thank you all for your input.

 

[cadpoint]

... I have always been intrigued by lightning and will further track down more information on the subject . . .

Since your going you can read back to Ben Franklin, enjoy ...

Oh shoot that's the Lighting rod ... never mind

 

[quogueelectric]

Air terminal

Since your going you can read back to Ben Franklin, enjoy ...

Yes I am looking for an all night kite store and a locksmith with a big Key.