Ground Rod for Light Pole

[charlie b]

I am having a disagreement with a client over the question of whether a metal light pole needs to have a nearby ground rod with a wire connecting the rod to the pole. I surmise that he is concerned over the possibility of a short from the ungrounded conductor to the pole itself, with a person leaning against the pole at the time. I tried to explain that that was the purpose of the EGC, and that (in the absence of an EGC) creating a path into planet Earth would not make the pole safe to touch. I would like to have a code reference handy, for the next time we discuss the issue, as a means of backing up my point of view.

Here is what I take from the NEC:

• The light pole is a ?structure,? in the context of the article 100 definition.
• The light pole does not need a local disconnecting means, because of Exception 3 to 225.32.
• The light pole does not need a ground rod, because of the Exception to 250.32(A).

Do I have adequate support for my point of view? Is there something I have missed?

 

[don_resqcapt19]

You have the code correct and there is no electrical or safety reason to install an grounding electrode at a light pole, but specs often require one.

 

[A/A Fuel GTX]

Around here, ground rods are always installed in addition to the EGC. However, it is optional and I believe you have the ammunition to prove it to your client. However, if the client wants to add them, why not? It can't hurt and doesn't cost much more.

 

[dicklaxt]

Been down the road a few times on that issue and as most are saying it is done more often than not but as you point out is not technically required.

Lightning protection may come into play tho,if the poles are intended to be a great big lightning rod then it must have a rod as lightning currents can't be imposed on fault current systems or something like thats if I remember correctly but don't have a code reference but its there somewhere.

dick

 

[scotteng]

NEC 250.32(A) states a separate building or structure shall have a grounding electrode or grounding electrode system. The exception to this requirement is that the grounding electrode is not required if the separate structure is fed by a single circuit, including a multi-wire branch circuit, and an equipment grounding conductor is run with the branch circuit conductors. Light poles are generally fed by a single circuit and therefore, it is permitted but not required to omit installing the grounding electrode at the pole. IMO, It is not a code violation to install a ground rod and grounding electrode conductor at each pole. There are two ?camps? on the value of driving a ground at the pole. One is that they provide no additional value (but don?t degrade the system in any way), and the other is that they will provide a low resistance path to ground for a direct lightning strike and prevent the majority of the strike surge from getting onto building/site wiring system. I am in the latter camp and believe that if it can?t harm and could help, it is better to install the ground rod.

 

[tom baker]

NEC 250.32(A) states a separate building or structure shall have a grounding electrode or grounding electrode system. The exception to this requirement is that the grounding electrode is not required if the separate structure is fed by a single circuit, including a multi-wire branch circuit, and an equipment grounding conductor is run with the branch circuit conductors. Light poles are generally fed by a single circuit and therefore, it is permitted but not required to omit installing the grounding electrode at the pole. IMO, It is not a code violation to install a ground rod and grounding electrode conductor at each pole.

However, Art 225 requires every separate building or structure to have a disconnecting means, 225.32, and the disconnecting means has to be suitable as a service disconnect. Once you install a disconnect, you no longer have a branch circuit, you have a feeder. A building with a feeder requires a grounding electrode system. So the application of a branch circuit without a grounding electrode is very limited and can only be used at out buildings for dwelling units

But exception 3 to 225.32 exempts towers or poles used as lighting standards from having a disconnecting means.

Charlie the debate over ground rods at metal lighting poles has no end or reason why its done. I call them time and material ground rods. I have an IEEE paper on the effectiveness of the concrete pole base and it indicates the concrete is just as good as a ground rod.

But install a ground rod if it makes your client happy, but only with the required EGC.

 

[ceb58]

Around here, ground rods are always installed in addition to the EGC. However, it is optional and I believe you have the ammunition to prove it to your client. However, if the client wants to add them, why not? It can't hurt and doesn't cost much more.

Why would you try to prove the customer wrong in this situation. Code wise, no, a rod is not required. If the customer will sleep better then drive the rods and charge accordingly. Why leave money on the table. Now if he thinks you are going to bear the cost then you pull out the code book.

 

[TimK]

Concrete Encased Electrode

Concrete Encased Electrode

Satisfy his need for additional ground and tell him you will add a concrete encased electrode and then just tie a #6 to the rebar. Acorn is for use in concrete, quick and easy. We have also done it with a coil of #6 solid bare coiled in the bottom before pour, but that was discussed here on the forum, and I realized I was wrong.:ashamed:

 

[tsamples]

Check with the Authority Having Jurisdiction. In some cases the Building Official will require a ground rod for lightning protection.

 

[roger]

Check with the Authority Having Jurisdiction. In some cases the Building Official will require a ground rod for lightning protection.

Unless the AHJ has made this a formal requirement it's nothing more than a "want"


Roger

 

[hurk27]

I am having a disagreement with a client over the question of whether a metal light pole needs to have a nearby ground rod with a wire connecting the rod to the pole. I surmise that he is concerned over the possibility of a short from the ungrounded conductor to the pole itself, with a person leaning against the pole at the time. I tried to explain that that was the purpose of the EGC, and that (in the absence of an EGC) creating a path into planet Earth would not make the pole safe to touch. I would like to have a code reference handy, for the next time we discuss the issue, as a means of backing up my point of view.

Here is what I take from the NEC:

• The light pole is a “structure,” in the context of the article 100 definition.
• The light pole does not need a local disconnecting means, because of Exception 3 to 225.32.
• The light pole does not need a ground rod, because of the Exception to 250.32(A).

Do I have adequate support for my point of view? Is there something I have missed?

You missed 250.4(A)(5)

250.4(A)(5) Effective Ground-Fault Current Path. Electrical
equipment and wiring and other electrically conductive material
likely to become energized shall be installed in a
manner that creates a low-impedance circuit facilitating the
operation of the overcurrent device or ground detector for
high-impedance grounded systems. It shall be capable of
safely carrying the maximum ground-fault current likely to
be imposed on it from any point on the wiring system
where a ground fault may occur to the electrical supply
source. The earth shall not be considered as an effective
ground-fault current path.

I would include the graphic that has been posted on here so many times that shows how the 3' shell around the pole will have a 90 volt difference of potential.



Also I would point out that the liability of not installing an EGC and the fact it could hurt or kill someone and could land them in jail facing charges or cost them everything they have.

Also if there intent is not to install an EGC, and they still wish you to provide a electrode, in no way would I do this, this is one of those jobs that I would walk away from.

 

[jazer]

I love this argument, especially about lightning protection. The idea of a tiny little #6 copper wire disipating a lightning strike had always made me laugh. Same goes for driving rods at outdoor distribution centers, generators and the such. Then, I listened to a Mike Holt webinar on this very subject, and the man himself made fun of the idea! It almost sounded like he was getting mad when someone asked the question concerning lightning protection! He explained that is why there are seperate standards for lightning protection, not the practice of driving ground rods.

 

[Stevareno]

Even though it may not be required by the NEC, inspectors around here will require what is spec'ed on the print.
If the print shows a ground rod or coil of wire at the bottom of the pole footing, then that is what you have to do.
If you want to do something differently, then you have to have the prints redrawn an approved by the city.

 

[Cavie]

Florida DOT light poles sit on a 8' or deeper concrete reinforced with rebar base. This rebar is not used as a ufer. The poles require 20' copper ground rods. AND must meet 25 ohms or less. go figure.