Grounding electrode at exterior light poles

[xptpcrewx]

It is never the structure that benefits from the grounding electrode system, only the electrical equipment on or in the structure.

This isn’t 100% accurate. Electrical systems installed on separate isolated structures can create additional hazards. This could be one reason for adding a GE.

So you would require a GE at the outside AC unit sitting on a concrete pad?

You say “you”, but I assure you it’s not me that’s requiring anything. I am simply reading the text in the NEC as is. I’m having difficulty with most of these responses because they mostly seem like conjecture and opinions rather than official interpretation and intent.

You can put as many electrodes in as you want, but in reality, they don't serve much purpose on an under 1000 volt electrical system.

I tend to agree. See post #8 as that explains it best.

 

[xptpcrewx]

If you had a shed and you install electrical to the shed then that shed becomes a structure for electrical purposes.

Where exactly are you getting this from? It’s not in the definition. A structure is a structure is a structure and doesn’t need to become one for electrical purpose. It just is.

The concrete base that the light sets on is not supplied with power, the pole itself is but that is exempt by definition. As stated before a/c units are not structures etc

Not trying to be difficult but can you please provide direct references?


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[don_resqcapt19]

....
You say “you”, but I assure you it’s not me that’s requiring anything. I am simply reading the text in the NEC as is. I’m having difficulty with most of these responses because they mostly seem like conjecture and opinions rather than official interpretation and intent.
....

As far as I know an official interpretation, (Formal Interpretation) has never been issued on the definition of structure.
Based on the PI for adding the word "equipment" the intend is that the concrete base with the light pole on the base, or the concrete pad with an AC unit on it are not structures. However the only enforceable language is the words you see in the code book.

 

[Dennis Alwon]

Where exactly are you getting this from? It’s not in the definition. A structure is a structure is a structure and doesn’t need to become one for electrical purpose. It just is.


Not trying to be difficult but can you please provide direct references?


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So If I pour a slab outside for nothing do you need to install a grounding electrode conductor ? Of course not.... The slab or footing is not the issue and the nec only cares once there is electric going to it not a non electrical structure. If that shed had no wiring then no grounding electrode conductor is needed.

You are overthinking this

 

[Fred B]

Add a ground rod or dont add a ground rod, generally the code makes optional the addition of ground rods beyond that used for the primary service connection and a remote structure. Biggest safety concern is what too many will do, drive a ground rod but don't run a equipment ground back to the panel that has the protection device and by doing so the circuit has no way to clear a fault, a ground rod by itself will not clear the fault. Mike Holt's poster:

Quote from ECM magazine:
"Another example is a parking lot luminaire installed on a pole. The luminaire and the pole are equipment covered by NEC Article 410, and the concrete base is a structure to which the equipment is mounted. The key difference between equipment and a structure is that structures are constructed, as indicated in the definition, while equipment typically is produced or manufactured in a facility and delivered to the site for installation. It is important to differentiate between equipment and structures to effectively determine when 250.32(A) requires a grounding electrode and when it is an option in accordance with 250.54."

 

[xptpcrewx]

So If I pour a slab outside for nothing do you need to install a grounding electrode conductor ? Of course not.... The slab or footing is not the issue and the nec only cares once there is electric going to it not a non electrical structure. If that shed had no wiring then no grounding electrode conductor is needed.

You are overthinking this

You are missing the point with my question. I am not suggesting anyone install a GE to a slab of concrete with no electrical on it. You just said it clearly - “The NEC only cares once there is electric going to it”. By this comment, an isolated pad with an AC unit or a light pole with concrete base require it. I’m not agreeing or disagreeing with the requirement. What I’m questioning is your logic, understanding and interpretation for something that’s not explicitly written.

 

[xptpcrewx]

Quote from ECM magazine:
"Another example is a parking lot luminaire installed on a pole. The luminaire and the pole are equipment covered by NEC Article 410, and the concrete base is a structure to which the equipment is mounted. The key difference between equipment and a structure is that structures are constructed, as indicated in the definition, while equipment typically is produced or manufactured in a facility and delivered to the site for installation. It is important to differentiate between equipment and structures to effectively determine when 250.32(A) requires a grounding electrode and when it is an option in accordance with 250.54."

I’m glad you bring this up. I read that too. Unfortunately if you read further, that article claims (without basis) that the light pole base is not a structure. This is the premise of what I am asking about.


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[Dennis Alwon]

Here is the logic... The definition of structure..... in the 2020 they added except equipment. We all know that equipment must be set on a base of some sort so why would that be written if they wanted the base to be a structure for the light pole.

There is also section 250.32

(A) Grounding Electrode.

A building(s) or structure(s) supplied by a feeder(s) or branch circuit(s) shall have a grounding electrode system and grounding electrode conductor installed in accordance with Part III of Article 250. Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

Exception:
A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the normally non–current-carrying metal parts of equipment.

Light poles are feed with a single circuit so why would we be required to add a grounding electrode system .

 

[don_resqcapt19]

I’m glad you bring this up. I read that too. Unfortunately if you read further, that article claims (without basis) that the light pole base is not a structure. This is the premise of what I am asking about.


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It is strictly an opinion as to what a structure may or may not be, and at this point, the only opinion that counts, is that of your AHJ.

 

[xptpcrewx]

Here is the logic... The definition of structure..... in the 2020 they added except equipment. We all know that equipment must be set on a base of some sort so why would that be written if they wanted the base to be a structure for the light pole.

There is also section 250.32

I don’t know. Only thing I can think of is because buildings or structures can be separate/isolated/remote and that in of itself can create a problem. What about running a feeder to the shed into a box and not supplying any equipment/loads?

Light poles are feed with a single circuit so why would we be required to add a grounding electrode system .

See post #8.[/QUOTE]

 

[Hv&Lv]

https://ksite.org/images/meeting/071817/wci_grounding_streetlighting_and_tc.pdf

 

[xptpcrewx]

It is strictly an opinion as to what a structure may or may not be, and at this point, the only opinion that counts, is that of your AHJ.

Thanks. I agree with you. Believe me, anywhere I can avoid installing a GE I will seriously consider not doing it. It would be nice for a formal interpretation to be issued to put this to rest.

 

[don_resqcapt19]

Thanks. I agree with you. Believe me, anywhere I can avoid installing a GE I will seriously consider not doing it. It would be nice for a formal interpretation to be issued to put this to rest.

You can request one from the NFPA. Your question has to be structured so that it can be answered "yes" or "no" and the process takes months as a Formal Interpretation is processed the same way as a code change...that is circulated to the Code Making Panel members and voted on by them.

However in many, if not most, cases the structure/equipment is fed by a single branch circuit and the exception to 250.32(A) says no GE is required.

 

[xptpcrewx]

You can request one from the NFPA. Your question has to be structured so that it can be answered "yes" or "no" and the process takes months as a Formal Interpretation is processed the same way as a code change...that is circulated to the Code Making Panel members and voted on by them.

However in many, if not most, cases the structure/equipment is fed by a single branch circuit and the exception to 250.32(A) says no GE is required.

Any idea why it must be structured as a “yes” or “no” question?

 

[tom baker]

The NEC long ago recognized a lighting standard or pole is a structure. Here is the code language to support that;
Article 225 has the requirements for wiring of the supply of utilization equipment located on or attached to a building, structure or poles.

Part II is buildings or other structures supplied by a feeder or branch circuit
225.31 Disconnecting means - means shall be provide to disconnection of all ungrounded conductors that supply or pass through the building or structure
225.32 Gives the location – readily accessible
Exception No 3 For towers or poles used a lighting standards the disconnecting means shall be permitted to be located elsewhere on the premises

Exception #3 was added many code cycles ago as lighting pole was considered a structure and required a disconnect. The CMP recognized having a fused disconnect (example) on the pole was not required.

So no disconnect, then clearly not a feeder, and no GE required,

 

[xptpcrewx]

I’m glad you bring this up. I read that too. Unfortunately if you read further, that article claims (without basis) that the light pole base is not a structure. This is the premise of what I am asking about.


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I want to clarify one thing. I mistakenly said the article claims (without basis) the light pole base is not a structure, when what I should have said is, the equipment and structure together do not trigger a GE requirement (without basis).

 

[tom baker]

On the issue of ground rods a lighting poles, my theory is when lights were first put on poles, they were supplied from an system with no EGC, so a ground rod was added. This habit carried over to today but has taken on the lightning protection myth. I researched this for Mike Holt, and I never found direct evidence of a foundation being damaged by lighting. In this article

The author did high voltage impulse testing of various footings with rebar and found no damage
The conclusion was

The article is from Aug 1970. Its copy righted but if you want a copy you can get one from the IEEE

 

[xptpcrewx]

On the issue of ground rods a lighting poles, my theory is when lights were first put on poles, they were supplied from an system with no EGC, so a ground rod was added. This habit carried over to today but has taken on the lightning protection myth. I researched this for Mike Holt, and I never found direct evidence of a foundation being damaged by lighting. In this article
View attachment 2556784
The author did high voltage impulse testing of various footings with rebar and found no damage
The conclusion was
View attachment 2556785
The article is from Aug 1970. Its copy righted but if you want a copy you can get one from the IEEE

All this is really saying is that concrete encased electrodes perform better than a grounding rod - which is no mystery and not particularly interesting.

This low resistance connection to earth is nice but useless unless the pole is bonded to the rebar.

 

[don_resqcapt19]

Any idea why it must be structured as a “yes” or “no” question?

Too many possible variations if they have to write sentences to give you an answer. Yes or no makes it very clear based on the conditions of your question. Note that FIs are not very common.

 

[texie]

Here is the logic... The definition of structure..... in the 2020 they added except equipment. We all know that equipment must be set on a base of some sort so why would that be written if they wanted the base to be a structure for the light pole.

There is also section 250.32



Light poles are feed with a single circuit so why would we be required to add a grounding electrode system .

I don't think 250.32 is relevant here as this is equipment, not a structure. As I and others have mentioned, take the case condensing unit on a slab/foundation away from the building. Many larger units have multiple branch circuits feeding them and no GES is required because it is equipment. Likewise light pole could have multiple branch circuits and still not need a GES.