Lightning Protection

[Grouch1980]

What's the difference between a lightning protection system versus a lightning prevention system? I've heard it several times, but can't find good definitions for it... is it in NPFA 780?

 

[hbiss]

One is real, the other imaginary.

-Hal

 

[OldBroadcastTech]

Well said !!

My observation to Radio Station Owners was 'You can never prove you have ENOUGH lightning protection, but Mother Nature will let you know if you DON'T have enough.

 

[Grouch1980]

... so what is each one and how are they different?

 

[drktmplr12]

understand the difference, you need to understand how lightning works. This is a pretty good diagram and explanation that won't take too much of your time:

a protection system provides a path of least resistance to the ground and may encourage strikes, but the system is designed so that the strike is safely grounded. think lighting rod, conductors routed down building to grounding grid

a prevention system claims to either (1) create enough insulation between the ground and the sky to prevent a strike altogether or (2) redirect charges from an area you do not wish for a strike to occur.

one is installed in nearly every critical facility in the country (protection system), and the other is not (prevention)

 

[Grouch1980]

a prevention system claims to either (1) create enough insulation between the ground and the sky to prevent a strike altogether or (2) redirect charges from an area you do not wish for a strike to occur.

aah ok. That's what I was missing. How do they create this insulation?

 

[drktmplr12]

aah ok. That's what I was missing. How do they create this insulation?

I don't know enough about it to even guess.

I do know I wouldn't design a "prevention" system

 

[Grouch1980]

I don't know enough about it to even guess.

I do know I wouldn't design a "prevention" system

Gather a bunch of rubber tires?

 

[cadpoint]

I love a good Etch-a-Sketch !

 

[OldBroadcastTech]

'corona discharge' systems ( or 'gadgets', take your pick) were VERY big with broadcasters in the 70's-80's

here's a web-site, I actually saw these installed on an FM tower over in Missouri

Lightning Protection Systems By Lightning Eliminators | LEC

Regardless of where lightning comes from Nature, God, Zeus doesn't matter. Lightning protection systems by LEC can still protect against it.

www.lightningprotection.com

now whether they actually helped is a good question, since this was after a devastating strike and we put in a TON (well, several hundred pounds) of ground rods and copper strap tying everything together at the same time.....the theory being that it doesn't matter that if, for a split second, the tower and equipment is several hundred or even thousands of volts above ground, as long as EVERYTHING is at the same potential....what kills equipment is the current flow between them if not at the same potential

At least that's the theory, your mileage may vary, as they say........I do know that I have been at that site when lightning struck the tower, and except for it being very bright (door was open) and very loud and my hair standing straight up, the transmitter and all else kept right on working

 

[LarryFine]

 

[Grouch1980]

View attachment 2563910 View attachment 2563911

Looks like fun.

 

[Sahib]

No. It is an engineering feat that the lightning hitting the plane and moving along the wing failed to ignite the fuel stored in the wing.

 

[ggunn]

No. It is an engineering feat that the lightning hitting the plane and moving along the wing failed to ignite the fuel stored in the wing.

Has a plane ever been set on fire by a lightning strike?

 

[Sahib]

Has a plane ever been set on fire by a lightning strike?

 

[xformer]

aah ok. That's what I was missing. How do they create this insulation?

Extremely large farday cage?

 

[Julius Right]

Lightning Prevention | Lightning Protection System

The basic form of lightning protection that many people are familiar with is the lightning rod. Lightning Rod Prevents Lightning Effects.

www.lightningprotection.com

 

[LarryFine]

Think of the plane's body as an equipotential bonding conductor.

No voltage difference between points means no current flow.

 

[Sahib]

Think of the plane's body as an equipotential bonding conductor.

No voltage difference between points means no current flow.

In post 11 photo, the lightning hit the plane at one point and exit at another point and that means current flow along the path(s) connecting the two points, damage avoided by extremely short duration of current flow thereby negligible temperature rise.

 

[LarryFine]

In post 11 photo, the lightning hit the plane at one point and exit at another point and that means current flow along the path(s) connecting the two points, damage avoided by extremely short duration of current flow thereby negligible temperature rise.

I'm referring to the entry and exit points being at the same potential eliminating voltage drop.