ground rods

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BKDog

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i got hit with a question which i could not anser today:

Why is it ok to drive a ground rod at a 90 angle or 45 or lay flat with stipulations like "no steeper than a 45" when 90 is ok. and why is the code so specific about 2.5 feet or deeper? I had some theories and am researching now but I told the kids that i would find out before I answered.
Any clues?
 
The mission is to get the rod into intimate contact with planet Earth. Driving it straight down is the best way to achieve that mission. If you can't do that, because of rocky soil or other constraints, then you can try at an angle. The rule is not "no steeper than 45 degrees," but rather "not to exceed than 45 degrees from the vertical." If you can't do that either, then dig a trench that is deep enough (2.5 feet) to make it effectively in contact with the planet.
 
I once had a theory based on some research that followed like this. The first "grounding" of electrical systems was on telegraph transmission lines and poles. Telegraphs lines could be conveniently run right along already installed railroad tracks to connect town to town. However, the railroads leased or owned only a small strip of land barely wider than the tracks. So when the telegraph companies wanted to put lines and poles along the railroad tracks, they were very limited on space. They obviously needed to stay clear from the tracks and passing train, but also couldn't encroach into the neighboring property. Thus ground rods needed to be driven as perpendicular to the earth as possible.

This seemed to make perfect sense to me and nearly reality except that ground rods really didn't come into use until around 1918. This was well past the main telegraph years. It appears ground plates were a common grounding electrode during the telegraph days.

Other than that useless bit of information, I think Charlie has hit right on...
 
I am going to be honest and probably break some ethically binding rule that inspectors aren't suppose to reveil. So be it. I could care less at what angle a ground rod is driven. If I came across a ground rod driven at a 22? angle, however met every other requirement outlined by the NEC, I would approve the installation.

But to answer your question, yes. I think the 45? designation has something to do with the "angle of repose" issue and would result in a ground rod not suitably deep enough nor with enough compacted earth "above" its length. But then they allow you to bury it horizontally throwing that whole idea right out of the "ground" (pun intended).

Bottom line. Don't overthink the issue or try to reason it out. The entire section really doesn't have any good substaniation to exist and would likely not result in ANY type of hazard as a result of not following the rule.

So my official response is: Please follow the rule.
 
Jhaney said:
so charlie your saying if I drive the ground rod at 22? (pulled that out of the air) then its too steep? Or am I thinking backwards?
Click to expand...

You are thinking correctly. Remember when you drive the rod straight then it is driven at 90 degrees to the earth. So 22 degrees would be at too horizontal to make enough contact down deep. I do agree with Bryan. I can't imagine it would make much difference.

I guess it goes back to the rod not having enough contact with good earth-- thus the 2.5 feet deep if you lay it in a trench ( zero degrees)
 
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