Grounding...

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Old 07-20-05, 01:58 PM
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Grounding...

How/why does grounding work? Why is electricity attracted to the earth and want to find the path of least resistance to it?
 
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Old 07-20-05, 02:03 PM
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Whole books are written to answer that exact question. So I don't think I can answer it in one post.

There are multiple different kinds of grounding and they serve multiple different purposes. One kind of grounding is designed to trip the breaker in the event of certain kinds of faults. Another kind of grounding is designed to keep all electrical equipment at a common potential so that there aren't stray currents. Another kind of grounding is intended to lessen the damage of nearby electrical strikes or downed power lines.

Electricity always seeks a point of lower potential, in the same way that a ball always falls to the earth when you drop it. Electricity is composed of trillions of electrons, and they use every possible path to get to a lower potential, in inverse proportion to the resistance of that path. This is similar to water in a bucket with holes in the bottom. The water will come out all the holes, with more coming out the bigger holes than the smaller holes.

There are even certain situations where we don't provide grounding on purpose, because grounding can sometimes increase the hazard. In most cases, grounding is a mixed bag, offering both advantages and disadvantages. When the advantages outweigh the disadvantages, we ground.

The code uses many similar terms, but "ground", "grounding", "grounding wire", and "grounded wire" are all different things. What some people call "grounding" is actually not grounding at all, but "bonding".

So there's the 0.001% of the book.
 
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Old 07-20-05, 03:48 PM
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Originally Posted by John Nelson
Whole books are written to answer that exact question. So I don't think I can answer it in one post.

There are multiple different kinds of grounding and they serve multiple different purposes. One kind of grounding is designed to trip the breaker in the event of certain kinds of faults. Another kind of grounding is designed to keep all electrical equipment at a common potential so that there aren't stray currents. Another kind of grounding is intended to lessen the damage of nearby electrical strikes or downed power lines.

Electricity always seeks a point of lower potential, in the same way that a ball always falls to the earth when you drop it. Electricity is composed of trillions of electrons, and they use every possible path to get to a lower potential, in inverse proportion to the resistance of that path. This is similar to water in a bucket with holes in the bottom. The water will come out all the holes, with more coming out the bigger holes than the smaller holes.

There are even certain situations where we don't provide grounding on purpose, because grounding can sometimes increase the hazard. In most cases, grounding is a mixed bag, offering both advantages and disadvantages. When the advantages outweigh the disadvantages, we ground.

The code uses many similar terms, but "ground", "grounding", "grounding wire", and "grounded wire" are all different things. What some people call "grounding" is actually not grounding at all, but "bonding".

So there's the 0.001% of the book.

Very interesting info, thanks for that. Sounds like it was a loaded question. Thanks again!
 
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