Service neutral bonding location
- Thread starter kmh
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Dale001289
Senior Member
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- Georgia
True. Fault that goes into the ground must come out. It does not 'disperse' into the unknown earth.
The GEC is important for reasons I won't go into here. But the EGC is what's really needed to clear a ground fault in a timely manner. So I disagree with your statement "but back to the Xfmr (via the GEC)." Ground fault current gets back to the xfmr primarily via neutral bonded to the EGC.
Dale001289
Senior Member
- Location
- Georgia
If a fault occurs within the circuit, on the conduit or at the end device, it will travel via the neutral/EGC back to Xfmr - this represents the vast majority of faults--But when a fault hits the earth or grid remote from the EGC, it wont simply disappear into the earth - it will go back to the Xfmr.
Hopefully everyone in this forum realizes current does not just disappear into the earth.
When a fault occurs to normally non current carrying paths that are conductive, that current travels via the EGC back to the Grounded Conductor at the transformer if wired correctly, and yes, this represents one type of fault condition.
Again. A lightning strike is not a fault.
I've never seen a transformer or overcurrent protection device ahead of a lightning strike....... have you?
Yes, a lightning strike does in fact simply disappear into the earth.
You can't stop a lightning strike by any amount of ground rods or grids.
If what you were saying were true, about a lightning strike traveling back up the GEC to the Grounded Conductor on a transformer in close proximity, lightning would destroy a ton of transformers each time one decided to strike the earth.
That's simply not the case.
JAP>
Where does it come out at?
If a strike occurs in Colorado on a stormy day, does it come back up out of the ground in China and jump back up into the sky on a perfectly beautiful day ?
JAP>
Dale001289
Senior Member
- Location
- Georgia
I used to think lightning would dissipate into the earth too - but it doesn't work that way. It will seek a path to come out of the earth - it seeks ALL resistances, the sum of which equals the path of least resistance. That's why the people Hong Kong will never see a lightning strike in the US.
Lightning is a whole different story than ground fault current. Charge a capacitor with DC voltage, then take the voltage connection away. Now jumper one side of the capacitor to the other. You'll get momentary current flow as the charges equalize. That's lightning. It's two opposite charges equalizing.
Dale001289
Senior Member
- Location
- Georgia
Dale001289
Senior Member
- Location
- Georgia
Dale001289
Senior Member
- Location
- Georgia
Call it what you want.... but in a major lightning strike you could have hundreds of thousands of Amps/Volts hitting the earth — where does it go after it hits the earth?
Answer: it travels horizontally thru the earth seeking a path to come out - and where is the least resistance? Is it a tree? A fence?
Remember the transformer XO is at very low resistance
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For the Lightning strike to hit the earth, or a strike from the earth to the clouds, that portion of the cloud to earth or earth to cloud path had to be the path of least resistance to begin with.
Otherwise, the lightning strike would have never happened in the first place.
JAP>
Dale001289
Senior Member
- Location
- Georgia
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>
Why would it search for that point?
JAP>
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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