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Old 03-09-2011, 08:52 PM   #16
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Household current wants to return to the pole transformer. Lightning wants to go to the (real) ground or earth. Hence the ground rod or ground plate.

Now a lightning bolt can be thousands of amperes, enough to melt a #6 wire. But the National Electric Code specifies (for most services) a #6 wire so I do not know the theory behind that.

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Old 03-09-2011, 08:57 PM   #17
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The grounding electrodes are there for things like lightning strikes. They are NOT there to assist in short circuit conditions in your premises wiring.

You can hook one of your hot lines directly to a ground rod, and it will just bleed electricity into the ground, running up your electric bill.

ASSUMING a ground rod has a resistance of 25 Ohms, then a 120 Volt line connected to it would draw 4.8 Amps --- much less than what is required to trip out a 15 Amp circuit breaker. IT ain't there to trip the breaker(s) for short circuits, but to give lightning and other catastrophic events a place to discharge.
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Old 03-09-2011, 09:00 PM   #18
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Jeters, go back and read post #9. The grounding electrode has nothing to do with current flow.
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Old 03-09-2011, 09:00 PM   #19
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Quote:
Originally Posted by AllanJ View Post
...a lightning bolt can be thousands of amperes, enough to melt a #6 wire. But the National Electric Code specifies (for most services) a #6 wire so I do not know the theory behind that.
For the most part, a lightning bolt will not melt a #6 wire (too short a duration), but made electrodes (such as ground rods, plates, pipes, etc) can't dissipate any more juice than a #6 can carry, hence the Code limitation on that wire size. Installing a larger wire size is a waste of resources.
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Old 03-09-2011, 09:06 PM   #20
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Thanks everyone for the replies , these forums are very helpful and interesting, one thing I do know is that this home inspector that made the original post has to be just confused by now, thanks again, take care.
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Old 03-09-2011, 09:10 PM   #21
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They wouldn't want every short relying on the main neutral in residential, the #6 would take it to the plate unless theres a big short where the amprage exceeds the panel rating, (barley happens) then the neutral would take It, right? Just wondering,
And what will happen with the current that "goes to the plate?" It has to get back to the source.

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