Grounding electrode at exterior light poles

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confused-engineer81

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My question is really short.

Does the NFPA 780 reference exterior light poles and have requirements for this? I checked but couldn't find one. I know that adding a grounding rod at each light pole base isn't required by the NEC but is a common practice.

Also, are there whitepapers discussing the effectiveness of lightning protection with and without a grounding rod?
 
confused-engineer81 said:
My question is really short.

Does the NFPA 780 reference exterior light poles and have requirements for this? I checked but couldn't find one. I know that adding a grounding rod at each light pole base isn't required by the NEC but is a common practice.

Also, are there whitepapers discussing the effectiveness of lightning protection with and without a grounding rod?
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Maybe someone has better insight but a grounding electrode would seem to be required by the NEC if the light pole is considered a “structure”.
 
Xptpcrewx said:
Maybe someone has better insight but a grounding electrode would seem to be required by the NEC if the light pole is considered a “structure”.
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Correct.

But there is an exception. The exception is under NEC 250.32 (A)

A grounding electrode isn't required whre only a single branch circuit supplies the structure

I should have said this in the original post. Im looking for hard proof that either the grounding rod at the lightpole is necessary, or it does nothing and is a waste of money. Proof as in a whitepaper or code reference saying its necessary
 
A luminaire on a pole is equipment, not a building or structure. See Article 100 for equipment and structure definitions. As such, no GE is required and 250.32(A) Exception is not even applicable (no matter how many branch circuits). A GE at a light pole is an option per 250.54 but not required.
If an NFPA 780 system is installed that may require a GE but not do to the NEC.
 
texie said:
A luminaire on a pole is equipment, not a building or structure. See Article 100 for equipment and structure definitions. As such, no GE is required and 250.32(A) Exception is not even applicable (no matter how many branch circuits). A GE at a light pole is an option per 250.54 but not required.
If an NFPA 780 system is installed that may require a GE but not do to the NEC.
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Can you clarify why the structure the pole is mounted to is not considered a “structure” for the purposes of requiring a grounding electrode?
 
confused-engineer81 said:
Correct.

But there is an exception. The exception is under NEC 250.32 (A)

A grounding electrode isn't required whre only a single branch circuit supplies the structure

I should have said this in the original post. Im looking for hard proof that either the grounding rod at the lightpole is necessary, or it does nothing and is a waste of money. Proof as in a whitepaper or code reference saying its necessary
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The answer depends. If there is a possibility of the pole becoming energized in such a way where the fault would persist and cause step/touch potentials without clearing, or if it became energized by some other means (as with lightning or nearby high-voltage circuits coming into contact with the pole), a grounding electrode could either create a more hazardous situation or provide a safer installation. The soil resistivity, remoteness of the circuit, weather conditions, bonding, other nearby systems, and whether the electrical system is grounded/ungrounded all comes into play. Grounding electrodes do work, but having only one or installing it in an ineffective location may not present any noticeable benefits. There are many standards and references out there. One is the IEEE Green Book and another is Industrial Power System Grounding Design Handbook. You can also read about the fall of potential grounding test to see how adding grounding electrodes influence one another.
 
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I have an article on effectiveness of rebar in pole base. I can send you title tommorrow, its copyrighted from IEEE.
 
texie said:
A luminaire on a pole is equipment, not a building or structure. See Article 100 for equipment and structure definitions. As such, no GE is required and 250.32(A) Exception is not even applicable (no matter how many branch circuits). A GE at a light pole is an option per 250.54 but not required.
If an NFPA 780 system is installed that may require a GE but not do to the NEC.
Click to expand...

thanks for the reply

Do you know of an NFPA 780 reference that might talk about this? I tried using a search PDF function but couldn't come up with anything.
 
Xptpcrewx said:
The answer depends. If there is a possibility of the pole becoming energized in such a way where the fault would persist and cause step/touch potentials without clearing, or if it became energized by some other means (as with lightning or nearby high-voltage circuits coming into contact with the pole), a grounding electrode could either create a more hazardous situation or provide a safer installation. The soil resistivity, remoteness of the circuit, weather conditions, bonding, other nearby systems, and whether the electrical system is grounded/ungrounded all comes into play. Grounding electrodes do work, but having only one or installing it in an ineffective location may not present any noticeable benefits. There are many standards and references out there. One is the IEEE Green Book and another is Industrial Power System Grounding Design Handbook. You can also read about the fall of potential grounding test to see how adding grounding electrodes influence one another.
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That's interesting. The question turns from, is this necessary or overkill to is this necessary or does it create a hazard. From what you said I would think I would never install a GE at the lightpole, only the ground from the panel.
 
confused-engineer81 said:
That's interesting. The question turns from, is this necessary or overkill to is this necessary or does it create a hazard. From what you said I would think I would never install a GE at the lightpole, only the ground from the panel.
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As I mentioned in my previous post, you are free to install one per 250.54. But again, a light on a pole is equipment just like any other such as an outside condensing unit, a non-SDS genset or any number of things that are routinely installed away from a building. All of which are equipment and do not require a GES.
 
confused-engineer81 said:
That's interesting. The question turns from, is this necessary or overkill to is this necessary or does it create a hazard. From what you said I would think I would never install a GE at the lightpole, only the ground from the panel.
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I wouldn’t dismiss it so quickly. Let’s say the light pole is electrically floating at its location, and an EGC is the only path back to the grounding electrode. A lightning strike at the light pole could be transferred into the building or wherever the grounding electrode is installed. Doesn’t seem like a very good situation….
 
Looking at NFPA 780... I don't think a lightpole would classify as a structure as it is defined (Not that I thought it was. Based on NEC 100 I referred to them as equipment.) But, how do articles 4.19.4 or 4.19.5 of NFPA 780 tickle your fancy for an answer?
 
Here is another post regarding Ground Rods at light poles

Ground Rods at Light Poles

250.32(A) tells us it is not required. I keep encountering people who cling to the urban legend that they, somehow, provide a necessary protection. I can make the case for a shock hazard, given that the EGC, and not the ground rod, provides protection. But what about lightning strikes? I am...
forums.mikeholt.com

And I caught crap for posting this... but I found it helpful once when debating this topic...
iaeimagazine.org

Are Your Streetlights Grounded?

It had been raining and the sidewalk was wet. This had been one of those summer storms where the temperature outside was a balmy 78 degrees. So the children playing on the sidewalk were in short pants, some were barefoot. One of these barefoot children, eight-year-old Sarah, was chasing Eric...
iaeimagazine.org iaeimagazine.org
 
Xptpcrewx said:
Anyone?
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I would say that because a light pole requires a base to create a completed system, that by the definition of Equipment in the NEC, it would be "used as a part of, or in connection with, an electrical installation.

If you build a shed, that is a structure because you do not have to put electrical devices with in it. Once you apply electric to it, now you have a structure which requires a ground.

That is my opinion at least.
 
Rock86 said:
I would say that because a light pole requires a base to create a completed system, that by the definition of Equipment in the NEC, it would be "used as a part of, or in connection with, an electrical installation.

If you build a shed, that is a structure because you do not have to put electrical devices with in it. Once you apply electric to it, now you have a structure which requires a ground.

That is my opinion at least.
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Thanks. Wondering if there is something more official than an opinion because the definition for structure in the NEC specifically states, “That which is built or constructed, other than equipment.”.

Concrete/footing/rebar is definitely something built or constructed. This is not like anything described in the definition of Equipment which states, “A general term, including fittings, devices, appliances, luminaries, apparatus, machinery, AND THE LIKE used as a part of, or in connection with, an electrical installation.”.

Applying this definition would seem to suggest the base to which the light pole will be mounted is in fact a structure and not equipment.
 
Xptpcrewx said:
Thanks. Wondering if there is something more official than an opinion because the definition for structure in the NEC specifically states, “That which is built or constructed, other than equipment.”.

Concrete/footing/rebar is definitely something built or constructed. This is not like anything described in the definition of Equipment which states, “A general term, including fittings, devices, appliances, luminaries, apparatus, machinery, AND THE LIKE used as a part of, or in connection with, an electrical installation.”.

Applying this definition would seem to suggest the base to which the light pole will be mounted is in fact a structure and not equipment.
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I'll grant you that the definition is some what ambiguous. But to use your logic that would mean that equipment such as a genset or a condensing unit, etc. attached to a concrete pad/foundation located outside of a building would need a GES.
 
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