Service neutral bonding location

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kmh said:
Oooh, gotta disagree with that! A charge of one polarity accumulates in the clouds ( I think it's positive, but Google it yourself.) A charge of the opposite polarity accumulates in the ground. Eventually the potential difference is so high that the atmosphere ionizes creating a conductive path between the two opposite charges, thereby equalizing the potential difference. Current does not need to flow any farther than that. It's merely a matter of positive charges meeting negative charges to reach equilibrium. And this has nothing to do with returning ground fault current to a transformer XO.
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Oh man oh man,,,,,,,, we're getting somewhere now. :) :thumbsup:

JAP>
 
Although I would think the difference of potential would need to decrease between the 2 for the strike to happen.

JAP>
 
kmh said:
Oooh, gotta disagree with that! A charge of one polarity accumulates in the clouds ( I think it's positive, but Google it yourself.) A charge of the opposite polarity accumulates in the ground. Eventually the potential difference is so high that the atmosphere ionizes creating a conductive path between the two opposite charges, thereby equalizing the potential difference. Current does not need to flow any farther than that. It's merely a matter of positive charges meeting negative charges to reach equilibrium. And this has nothing to do with returning ground fault current to a transformer XO.
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jap said:
If a lightning strike hit out in the middle of a field with nothing electrical near the strike location, I find it hard to believe that it would travel through the earth until it found the XO terminal of a transformer for it to come back out of the ground.

Why would it search for that point?

JAP>
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A strike in an open field would still result in the voltage/current traveling in the least resistive path - if NO transformer existed it would seek other sources such as a tree, a fence post or even a human being. Remember the earth itself is a relatively high resistance. That’s why it won’t travel to China


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Dale001289 said:
A strike in an open field would still result in the voltage/current traveling in the least resistive path - if NO transformer existed it would seek other sources such as a tree, a fence post or even a human being. Remember the earth itself is a relatively high resistance. That’s why it won’t travel to China


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What does a transformer have that would make a lightning strike that hit the ground make it want to head that way ?

Wouldn't it make more sense to say that if a lightning strike hit the transformer, the GEC, would give that current a path to the earth?


JAP>
 
jap said:
What does a transformer have that would make a lightning strike that hit the ground make it want to head that way ?

Wouldn't it make more sense to say that if a lightning strike hit the transformer, the GEC, would give that current a path to the earth?


JAP>
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If the transformer is solidly grounded it will be invariably least resistive path. If it has a high resistance ground the current will still flow to it but will be limited by the resistor. If the transformer is delta and corner grounded the current will still go there. In other words the lightning is traveling just like a ground fault on the EGC - except now it’s going via the earth.


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jap said:
What does a transformer have that would make a lightning strike that hit the ground make it want to head that way ?

Wouldn't it make more sense to say that if a lightning strike hit the transformer, the GEC, would give that current a path to the earth?


JAP>
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Most people think the GEC plays no role whatsoever in the circuit but in reality the GEC sees a very small percentile of current even under normal operation. If you put an ammeter on it you may see 1-2% with 98%-99% on the neutral, for example. Under fault condition the same relative percentile of current would flow on the GEC just a larger amount.


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Dale001289 said:
Most people think the GEC plays no role whatsoever in the circuit but in reality the GEC sees a very small percentile of current even under normal operation. If you put an ammeter on it you may see 1-2% with 98%-99% on the neutral, for example. Under fault condition the same relative percentile of current would flow on the GEC just a larger amount.


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I don't disagree with that.

I'm still wanting to hear why a lightning strike out in the middle of a field to the earth would seek an XO terminal of a transformer, Tree, fencepost or human.

JAP
 
Dale001289 said:
If the transformer is solidly grounded it will be invariably least resistive path. If it has a high resistance ground the current will still flow to it but will be limited by the resistor. If the transformer is delta and corner grounded the current will still go there. In other words the lightning is traveling just like a ground fault on the EGC - except now it’s going via the earth.
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BS - there is no connection between a lightning strike and an electrical system. C'mon, how do you even relate these two sources of energy?
 
jap said:
I don't disagree with that.

I'm still wanting to hear why a lightning strike out in the middle of a field to the earth would seek an XO terminal of a transformer, Tree, fencepost or human.

JAP
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It’s all about resistances. For example take a simple 2-wire 24VDC circuit with a 10A load. Add 3 resistors in parallel-one at 100 Ohms one at 10 Ohms and one at 1 Ohm.
Where would most of the current flow on this circuit? Across the 1 Ohm resistor of course - and the least amount would flow across the 100 Ohm.
It’s the same thing with a ground fault or lightning strike.
The path will go across ALL varying resistances however most of the current will flow to the least resistance “source” similar to a ground fault on an EGC - we know ground fault always flows back to the source - which is the transformer.

Now let’s say you’re waking in a large open field and lightning suddenly hits the earth. The current will travel horizontally through the earth toward all resistances - trees, posts, etc (like the example above with resistors). Now what happens?
Unless you are wearing shoes with 3 inch thick rubber soles some of the current will likely enter your foot, travel through your body and exit your other foot once it hits the ground. Unfortunately you’d probably be dead at this point.
This is why LPI-175 states you should kneel down on the tips of toes if suddenly you find yourself caught in a lightning storm and no cover


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Dale001289 said:
It’s all about resistances. For example take a simple 2-wire 24VDC circuit with a 10A load. Add 3 resistors in parallel-one at 100 Ohms one at 10 Ohms and one at 1 Ohm.
Where would most of the current flow on this circuit? Across the 1 Ohm resistor of course - and the least amount would flow across the 100 Ohm.
It’s the same thing with a ground fault or lightning strike.
The path will go across ALL varying resistances however most of the current will flow to the least resistance “source” similar to a ground fault on an EGC - we know ground fault always flows back to the source - which is the transformer.

Now let’s say you’re waking in a large open field and lightning suddenly hits the earth. The current will travel horizontally through the earth toward all resistances - trees, posts, etc (like the example above with resistors). Now what happens?
Unless you are wearing shoes with 3 inch thick rubber soles some of the current will likely enter your foot, travel through your body and exit your other foot once it hits the ground. Unfortunately you’d probably be dead at this point.
This is why LPI-175 states you should kneel down on the tips of toes if suddenly you find yourself caught in a lightning storm and no cover
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What about cloud to cloud lightning? Or intra-cloud lightning? Lightning does not travel "toward all resistances". Lightning is an electrostatic discharge between to oppositely charged bodies that equalizes the charges between the bodies. The GEC and grounding electrode try to give lightning a low impedance path to earth to avoid damage to the electrical system, but it is debatable on how effective it is in doing its job.
 
packersparky said:
What about cloud to cloud lightning? Or intra-cloud lightning? Lightning does not travel "toward all resistances". Lightning is an electrostatic discharge between to oppositely charged bodies that equalizes the charges between the bodies. The GEC and grounding electrode try to give lightning a low impedance path to earth to avoid damage to the electrical system, but it is debatable on how effective it is in doing its job.
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After lightning hits the earth is the topic of conversation - not what it does in the clouds


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Dale001289 said:
After lightning hits the earth is the topic of conversation - not what it does in the clouds


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Lightning acts the exactly same way from cloud to cloud as it does from cloud to earth. It is just equalizing the charges between the two. Once it hits the earth it is not seeking a tree, a transformer, or anything else.
 
packersparky said:
Lightning acts the exactly same way from cloud to cloud as it does from cloud to earth. It is just equalizing the charges between the two. Once it hits the earth it is not seeking a tree, a transformer, or anything else.
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Thank God.

I'm not alone on this one.

JAP>
 
Service neutral bonding location

packersparky said:
Lightning acts the exactly same way from cloud to cloud as it does from cloud to earth. It is just equalizing the charges between the two. Once it hits the earth it is not seeking a tree, a transformer, or anything else.
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Everyone knows how lightning acts From clouds to earth - positive to negative charges equalizing.
But please back up your claim ....”once it hits the earth it is not seeking a tree a transformer or anything else”.
Are you another one who thinks it dissipates into the earth?


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jap said:
Thank God.

I'm not alone on this one.

JAP>
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No you’re not alone. The vast majority of people don’t understand how lightning strikes react once it hits the earth. Lightning is not a magical mystical phenomenon - like any electrical current it’s governed by the laws of physics.



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Dale001289 said:
No you’re not alone. The vast majority of people don’t understand how lightning strikes react once it hits the earth. Lightning is not a magical mystical phenomenon - like any electrical current it’s governed by the laws of physics.



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And it seems you don't understand fault clearing which is the conversation we started out having before this turned into a lightning storm.

JAP>
 
jap said:
And it seems you don't understand fault clearing which is the conversation we started out having before this turned into a lightning storm.

JAP>
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LOL! Really?
The GEC bonds directly to the grounding electrode system and thereby establishes a low impedance (fault) path back to the transformer. This is exactly what we were talking about.
In other words it serves to mitigate this: NEC Article250.4(A)(1) “Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.”

I don't know how I can make it any simpler. If you don't understand by now you probably never will....
 
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