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Hollow grounding electrode


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I came across a hollow, relatively light gauge galvanized steel tube used as a grounding rod today. I don't know the actual thickness since the top was distorted due to being mauled by a hammer, but I suspect it was simply a piece of conduit re-purposed for this use. Age about 20 years or so, and rusting pretty heavily at the soil line. Seems fishy at best.

I wrote it up for replacement simply due to the rust, (and the likelihood that it wasn't 8' deep) but I'm curious if anyone is aware of any hollow rods that are/were OK?

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(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.44 m (8 ft) in length and shall consist of the following materials.

(a) Grounding electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size ?) and, where of steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.

(b) Grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm ( in.) in diameter, unless listed and not less than 12.70 mm (? in.) in diameter.

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Thanks for the replies. It may be a regional thing, but I might see one hollow rod for every fifty solid ones. Generally, the hollow ones are on older installations.

I always wiggle solid rods to try to gauge whether they are possibly too short, but I don't grab or wiggle the older, hollow ones precisely because I am afraid they might break. On a related note, this pic is of a rod I easily pulled out that was inserted all of 6" deep...and most of that was through gravel. As you can see the total rod length was less than 2'. The home was built in 2002 in a town that does have muni inspections. It appears that the inspector was sleepwalking that day.

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tn_201212211414_REALLY%20short%20ground%20rod.jpg

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I came across a hollow, relatively light gauge galvanized steel tube used as a grounding rod today. I don't know the actual thickness since the top was distorted due to being mauled by a hammer, but I suspect it was simply a piece of conduit re-purposed for this use. Age about 20 years or so, and rusting pretty heavily at the soil line. Seems fishy at best.

I wrote it up for replacement simply due to the rust, (and the likelihood that it wasn't 8' deep) but I'm curious if anyone is aware of any hollow rods that are/were OK?

Still allowed today, as Chad pointed out. I believe that they're supposed to be at least 3/4".

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21 might mean mm which would=3/4" id mip?

I guess my question would be, Is 3/4" thinwall (EMT?) conduit suitable or should it be rigid conduit?

I just looked through several old editions of the NEC and they all say pretty much the same thing -- 3/4" pipe or conduit.

Your interpretation is as good as mine as far as EMT vs RMC etc.

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