Column base grounding

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charlie

charlie

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Indianapolis
My company has always specified a coil of #6 solid Cu coiled on the bottom of precast concrete st. ltg. column bases. This wire is wrapped around one of the anchor bolts and the tail left long enough to reach the grounding termination at the hand-hole.

It is my opinion that this wire or a ground rod installation is not required. Therefore, I am looking for published papers that will either back up or refute my position. Links would be appreciated. :smile:
 
Can't answer your question, but the company I work for, we drive a g-rod at every pole base (but not in the base) and run the bare cu up for the hand hole
 
The '99 and '02 NFPA ROP's had some good articles on concrete encased electrodes... concrete in contact with the earth maintains a 35% moisture content and provides an excellent ground grid system. Here, we are required to use it if available ,, BUT.. not smaller than #4
See: 250.50 Grounding Electrode System.
All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.

Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete.

250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.

(3) Concrete-Encased Electrode. An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (? in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
 
Charlie,
The NEC does not require a grounding electrode at a light pole, at least not in most cases, however I would expect that your installations are not subject to the NEC. I don't know what the NESC would say. That being said, the only way to make the installation safe if it is supplied from a grounded system is to run an EGC from the power source.
 
Mr. Holt has had a lot to say about the useless nature of grounding light posts (presumably to protect the concrete bases) - he might have referenced some literature (?) (http://www.mikeholt.com/technical.php?id=grounding/unformatted/metalpoles&type=u&title=Ground%20Rod%20at%20Metal%20Poles%20a%20Waste?%20(8-5-2K))

On a side note - wrapping the wire around an anchor bolt, while better than nothing at all, seems lacking (in the realm of "low impedance path") ? Does your company have any literature to support the notion that a listed termination is not required ? (I'm interested in the reasoning, other than the cost of termination, that it was determined that a connection was not required ?)
 
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don_resqcapt19 said:
Charlie,
The NEC does not require a grounding electrode at a light pole, at least not in most cases, however I would expect that your installations are not subject to the NEC. I don't know what the NESC would say. That being said, the only way to make the installation safe if it is supplied from a grounded system is to run an EGC from the power source.
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I agree with the above statement and would like to add that when installing a GEC at a light pole, the code section to reference is 250.54.
 
tryinghard said:
Check out a Mike Holt newsletter “Grounding and Bonding Poster”. In summary he claims the ground rod serves no purpose except to spend money, I agree.
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Yes, but that newsletter says, "Lightning Protection. Nope, if lightning hits the pole, the lighting fixture is toast, with or without a ground rod."

I take some exception to that. I don't think anyone feels that a rod (or using the base as a CEE) will save the fixture. What it does stand a real good chance of saving is the interior wiring of the building that serves the light standard with power. It might also save nearby fixtures. I've seen an I-Line breaker that served parking lot lighting blown up in pieces all over the electrical room floor from a lightning strike that hit the pole. I don't know if a CEE or rod would have prevented that, but it might have helped limit the magnitude of the lightning's effects on the interior wiring.

I know the whole intent of that newsletter was to get the point across that a rod will not facilitate the operation of the OCPD on a fault, but it's not like the rod has no purpose whatsoever. It serves the same purpose as those installed at services.
 
The NESC doesn't require the grounding that I have described and you are correct, the NEC does not apply to these installations. The wrap around the anchor bolts is before the base is poured, the concrete will hold the #6 in place. The wrap is just to get the #6 in the vicinity of the anchor bolt, the bottom of the column will connect all of the anchor bolts together. A ground rod is only required when a base is poured in place where a customer is required to provide the base for our column.

Now, I have to go to the links you have provided and do some reading, thank you. :)
 
Marc, was the pole that was hit isolated from the earth in any way that would have a meaningful effect on lighting that just managed to jump hundreds of feet through the air?
 
iwire said:
Marc, was the pole that was hit isolated from the earth in any way that would have a meaningful effect on lighting that just managed to jump hundreds of feet through the air?
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I'm not sure where you're headed with that, but it was a set of bull horns on a wood pole with no down ground. At least a rod would have put some of the lightning's current that was on the fixture to the ground and less of it inside the building.
 
mdshunk said:
I'm not sure where you're headed with that, but it was a set of bull horns on a wood pole with no down ground. At least a rod would have put some of the lightning's current that was on the fixture to the ground and less of it inside the building.
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I never think of wood poles used for site poles. In that case I agree an added electrode might help .... but then again it I really don't know.


I assume Charlie is talking a metal pole bolted into a concrete base. In this case I can't imagine an added electrode will do anything.
 
iwire said:
I never think of wood poles used for site poles. In that case I agree an added electrode might help .... but then again it I really don't know.


I assume Charlie is talking a metal pole bolted into a concrete base. In this case I can't imagine an added electrode will do anything.
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I still see a lot of wood poles used for illuminating sports fields. Not new installs, but older, existing ones.
 
iwire said:
I know they exist, I just don't think that was what Charlie was asking about and they don't come right to my mind. :smile:
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Actually, when I saw who posted the question, a wood pole was the first thing that came to my mind. They certainly have the ready means to install wood poles, since they have them on hand. When one talks about power companies and metal poles, I think more of a municipal utility rather than a rural utility.
 
Yeah, power companies wood poles, I hear you, but it was the hand hole, precast base and anchor bolts that made me think metal poles. :wink:
 
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