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Lightning Current

01/26/2017 8:05 AM

i just read the IEC standard on lightning protection as well as technical literature by pheonix contact,germany, where they say that 50% of lightning current flows up into system from earth termination system.any idea why? because from earth termination system ,all lightning current should be dispersed into soil and not travel back into system through earthing conductors.

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#1

Re: lightning current

01/26/2017 8:21 AM

<...pheonix contact,germany...> will certainly know, and the quickest route to the required information is to to the originator of the article.

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#2
In reply to #1

Re: lightning current

01/26/2017 8:46 AM

i do not think this will be happening only in Germany

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#3
In reply to #2

Re: lightning current

01/26/2017 8:52 AM

Er....the relevance of the opinion in #2⇑ is what, please?

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#4

Re: lightning current

01/26/2017 9:05 AM

If I understand lightning facts correctly, there can be flow in either direction - cloud to ground, or ground to cloud. Hence, flow from earth into the system.

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#7
In reply to #4

Re: lightning current

01/26/2017 10:53 AM

Ground to cloud flow is due to ionization of air in between cloud and ground.same cannot be said about system.for current flow potential difference is required.and what is the purpose of using earth termination system if current is going upward in system .

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Guru

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#8
In reply to #7

Re: lightning current

01/26/2017 11:18 AM

Read the guide in #5

It's all there, mate. Everything you wanted to know about how lightning behaves and more.

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#20
In reply to #8

Re: lightning current

01/26/2017 4:39 PM

Read? Read? You want him to read something?

I do not believe that he comes here to read.

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#9
In reply to #7

Re: lightning current

01/26/2017 11:44 AM

Where do you want this current originating from? Anywhere on your building, or a "guided system" that allows flow from earth through your system and out the rod on top the building. Check out lightning characteristics of flow from cloud to ground or the other direction and you'll see that earth can be essentially a positive or negative source when it comes to lightning and that huge potential difference involved.

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Guru

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#31
In reply to #7

Re: lightning current

01/27/2017 8:15 AM

Define 'system'!

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#32
In reply to #31

Re: lightning current

01/27/2017 9:13 AM

That requires at least an engineering degree, a contract, a non-disclosure agreement(?), a bill for services rendered and most importantly a payment for services rendered!

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#5

Re: Lightning Current

01/26/2017 10:22 AM
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#21
In reply to #5

Re: Lightning Current

01/26/2017 5:04 PM

Its a damn good guide, and clearly answers coolyaar's question (with pictures) in section 2.

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#6

Re: Lightning Current

01/26/2017 10:34 AM

<Sigh>

Lightning is a static electricity effect. Thus a net positive or negative charge exists in the cloud prior to the strike. Half of the time (50%) it will be positive and the other half it will be negative.

<Can I get a rim shot?>

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#10
In reply to #6

Re: Lightning Current

01/26/2017 11:52 AM

u can take whatever "shot" u like

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#11

Re: Lightning Current

01/26/2017 12:05 PM

Why do cows stand with their legs closer together in lightening storms?

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#12
In reply to #11

Re: Lightning Current

01/26/2017 12:26 PM

Even if we milk them during lightning?

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#28
In reply to #11

Re: Lightning Current

01/27/2017 5:06 AM

1. So they don't fall over.

2. They use their body like an awning which keeps their feet dry.

3. The closer arc gap makes a better Jacobs ladder.

4. So they can hope to be in an equipotential zone and not be fried. (In their case step and step).

5. Because they know something humans don't and they are keeping it a secret from us.

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#13

Re: Lightning Current

01/26/2017 1:38 PM

"50% of lightning current flows up..."

A clearer statement might be written as...in 50% of lightning strikes, the current flows up...

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#14

Re: Lightning Current

01/26/2017 2:09 PM

You, Coolyar has just the appetite for asking too many questions.

I wonder what you are up to these days.

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#15

Re: Lightning Current

01/26/2017 2:25 PM

Lighting travels to the path of least resistance. I do not know if you are going to introduced something, would actually make lightning to go down there as well. It might choose other way it certainly likes to discharge.

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#16
In reply to #15

Re: Lightning Current

01/26/2017 2:32 PM

If that was true then lightning would predictably follow the same path. Lightning paths are complicated.

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#17
In reply to #16

Re: Lightning Current

01/26/2017 2:36 PM

The atmosphere is like a sea of charges, one part goes negative and the other the opposite, so as the ground could take any polarity. But, I never seen lightning that actually goes up. Sidewards, yes.

Lightning is like a cast down god.

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#18
In reply to #17

Re: Lightning Current

01/26/2017 3:12 PM

Lightning paths involve the suspended wind induced charged particles, water drops and droplets, dust particles. While most of the time these paths move faster than the eye can see they do move up, down, sideways all the time. It only takes a lucky but very fast camera to see this.

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#19
In reply to #18

Re: Lightning Current

01/26/2017 3:19 PM

Spectacular. But, it's always grounded would you agree? I am curios to know if the spectrum of light tend towards the direction of the positive or is it the negative?

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#22
In reply to #19

Re: Lightning Current

01/26/2017 5:06 PM

Show me where this is grounded - cloud to cloud?

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#24
In reply to #22

Re: Lightning Current

01/26/2017 5:09 PM

What is ground but merely a difference of potential.

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#33
In reply to #24

Re: Lightning Current

01/29/2017 11:54 AM

I agree, all goes to the ground.

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#34
In reply to #33

Re: Lightning Current

01/30/2017 1:34 PM

<sigh> That's actually the opposite of what I am saying.

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#35
In reply to #24

Re: Lightning Current

01/30/2017 1:40 PM

This is ground.

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#36
In reply to #35

Re: Lightning Current

01/30/2017 2:29 PM

This is not a fine ground answer so no GA for you! Quite clearly the grounds are coarse in nature.

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#37
In reply to #36

Re: Lightning Current

01/30/2017 4:12 PM

What can I say. I actually prefer drip coffee to espresso.

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#23

Re: Lightning Current

01/26/2017 5:07 PM

i just read the IEC standard on lightning protection as well as technical literature by pheonix contact,Germany.

Thank you, you have honestly just made my day. You keep that personal learning and development up.

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#25
In reply to #23

Re: Lightning Current

01/26/2017 10:26 PM

Yeah, who would have thought that after all those years he would start reading the standards. There is an improvement if I see one.

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#26

Re: Lightning Current

01/27/2017 12:46 AM

I will just place a self explanatory drawing here to explain my point. A total 10KA lightning current struck the arrester. 5KA (50%) dispersed in soil through earth termination mesh but a 5KA (50%) can flow upward into electrical system through circuit protective conductors. Surge protection devices (SPD) are installed on circuit protective conductors to prevent this back flow into electrical system.

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#27
In reply to #26

Re: Lightning Current

01/27/2017 4:57 AM

At those sorts of currents one might reasonably expect some capacitive and inductive coupling between the lightning rod down-comer conductor on the outside of the building and the conductors within the building.

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#29

Re: Lightning Current

01/27/2017 5:26 AM

I don't think it is important how the lightning current will flow but more important how to protect buildings and installation against lightning. So, in my opinion, NFPA 780 it will be very interesting to study and not some theoretical presumptions.

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#30
In reply to #29

Re: Lightning Current

01/27/2017 5:31 AM

Sorry, I forgot IEC 62305 also, of course!

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