Lightning Protection

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WAbrothers said:
Howdy!

If someone is in contact with lighting protection when it is hit by lighting, will they get zapped?

Thanks,

Wojtek
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It depends on what else they are in contact with. If they are in contact only with the lightning protection system, they will not get "zapped"!
Think of a bird sitting on an uninsulated power line.
 
mgookin said:
It depends on what else they are in contact with. If they are in contact only with the lightning protection system, they will not get "zapped"!
Think of a bird sitting on an uninsulated power line.
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I imagine if you are holding onto the down-conductor standing on wet ground when the flag goes up, you're going to wind up roasty-toasty no matter what.
 
Not to mention that if a corona is eminating from the Lightning protection apparatus you are touching, you to should feel the effects of corona discharge around your body...No?

Ever connect yourself to a tesla coil and watch the sparks eminate from your eyeballs?
Nasty visual thought, but I never had the balls to try it.
 
I guess it depends what's coming through the LPS.
Are you hugging a trunk of the strike or is there a sizzle of a twig going through it?
 
I dont understand why some buildings in downtown have bare LPS conductors running down the side into the ground. Not even the bottom 8ft is in PVC.
 
WAbrothers said:
I dont understand why some buildings in downtown have bare LPS conductors running down the side into the ground. Not even the bottom 8ft is in PVC.
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All that would do is provide 8 feet of shrapnel in the event of strike. Corona effects can turn the air immediately around the conductor into a plasma that expands explosively and then collapses just as energetically. Hence the "boom".
 
gadfly56 said:
All that would do is provide 8 feet of shrapnel in the event of strike. Corona effects can turn the air immediately around the conductor into a plasma that expands explosively and then collapses just as energetically. Hence the "boom".
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But NFPA 780 G.1.1.2 Sideide flash and Touch Potential Reduction states that the down conductors must be shielded to at least a height of 8 ft.

Shielding down conductors to at least 2.4 m (8 ft) in height with electrically insulating materialthat is resistant to climatic conditions and impact.

Im still confused because I've seen an inspector pass exposed and encased LPS at ground level.
 
The secret is simple. The Empire State building, for exampe, has regularly been hit by lightning but no harm to life or property. Why?
 
mopowr steve said:
Not to mention that if a corona is eminating from the Lightning protection apparatus you are touching, you to should feel the effects of corona discharge around your body...No?

Ever connect yourself to a tesla coil and watch the sparks eminate from your eyeballs?
Nasty visual thought, but I never had the balls to try it.
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I've done this with my coil on an insulated platform. You can still feel it crawling on your skin...high frequency current, corona, whatever you want to call it.

Lightning is made up of "all frequencies" (1 Hz, through visible, to past the X-ray spectrum). A flying bird in the path of a lightning strike will still get blown to pieces. There is a lot more to lightning than just the electrical component, i.e., voltage, current, EMI, etc. It also creates a plasma as it passes through the atmosphere, so heat is an issue.

If someone is hanging on to any part of an LPS during a strike, they are just very well bonded.
 
WAbrothers said:
But NFPA 780 G.1.1.2 Sideide flash and Touch Potential Reduction states that the down conductors must be shielded to at least a height of 8 ft.

Shielding down conductors to at least 2.4 m (8 ft) in height with electrically insulating materialthat is resistant to climatic conditions and impact.

Im still confused because I've seen an inspector pass exposed and encased LPS at ground level.
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That's only Annex G for "Picnic Ground, Playgrounds, Ball Parks, and Other Open Places". You can't cherry pick out of a code for a structure which it may not apply to.
This is from the section which applies:

Chapter 4 General Requirements

4.9.11 Protecting Down Conductors. Down conductors located in runways, driveways, school playgrounds, cattle yards, public walks, or other locations subject to physical damage or displacement shall be guarded.
4.9.11.1 Metallic guards shall be bonded at each end.
4.9.11.2 The down conductor shall be protected for a minimum distance of 6 ft (1.8 m) above grade level.
 
WAbrothers said:
But NFPA 780 G.1.1.2 Sideide flash and Touch Potential Reduction states that the down conductors must be shielded to at least a height of 8 ft.

Shielding down conductors to at least 2.4 m (8 ft) in height with electrically insulating materialthat is resistant to climatic conditions and impact.

Im still confused because I've seen an inspector pass exposed and encased LPS at ground level.
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Annex G is for picnic grounds, playgrounds, ballparks and other open spaces, not buildings per se.

Context man, context...
 
Sahib said:
The secret is simple. The Empire State building, for exampe, has regularly been hit by lightning but no harm to life or property. Why?
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My best guess. Lightning is a high frequency event. The empire state building has tons of steel in it that direct the lightning's many paths deep into the earth. If the empire state building was not built with so much conductive material and instead was built with say plastic my guess is that it would suffer a lot of damage.
 
Ravenvalor said:
My best guess. Lightning is a high frequency event. The empire state building has tons of steel in it that direct the lightning's many paths deep into the earth. If the empire state building was not built with so much conductive material and instead was built with say plastic my guess is that it would suffer a lot of damage.
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That's pretty much it.

In Skywarn weather training, they referred to it as 'sheer mass'. Nothing beats large masses of electrically conductive metal to safely shunt a lightning bolt to ground.
 
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