2017 - 250.50

[Isaiah]

Can anyone out there give me an accurate description of what defines a "structure served"?

 

[charlie b]

Sure: "That which is built or constructed, other than equipment." (Article 100 definition.) It would include buildings, garages, carports, sheds, permanently installed canopies, yurts, cell phone towers, light poles, and one particular bus I know of that has had its wheels removed, sits on a street corner, has had cooking equipment brought in, and serves the best halibut and chips I have ever had. Not all of these things will have electricity at all, and not all that do have electricity will require a grounding electrode system.

 

[Isaiah]

Sure: "That which is built or constructed, other than equipment." (Article 100 definition.) It would include buildings, garages, carports, sheds, permanently installed canopies, yurts, cell phone towers, light poles, and one particular bus I know of that has had its wheels removed, sits on a street corner, has had cooking equipment brought in, and serves the best halibut and chips I have ever had. Not all of these things will have electricity at all, and not all that do have electricity will require a grounding electrode system.

Thanks Charlie. Your last sentence "Not all of these things will have electricity at all, and not all that do have electricity will require a grounding electrode system", is what has me concerned.

Assuming rebar meets criteria of concrete encased electrode per 250.52(3), would a foundation supporting a tank, steel structure or vessel that contains NO electrical equipment require rebar to be bonded?
I assume foundations for electrical equipment such as Power Transformers, Switchgear, MCC's and Motors would definitely require bonding. And lastly just to clarify, this is not the same as a Ufer grounding system but rather about bonding all grounding electrodes that are present.
(Application is for a large Refinery).

 

[charlie b]

I listed light poles as fitting in the definition of "structure." But a light pole does not need a ground rod, so long as it has a properly installed EGC. That is what I meant by the sentence you quoted.

 

[Isaiah]

I listed light poles as fitting in the definition of "structure." But a light pole does not need a ground rod, so long as it has a properly installed EGC. That is what I meant by the sentence you quoted.

I was not aware of that. Are you talking about wooden light poles or steel?

 

[charlie b]

I was not aware of that. Are you talking about wooden light poles or steel?

Either. It doesn't matter. Look at the exception to 250.32(A).

 

[Isaiah]

Either. It doesn't matter. Look at the exception to 250.32(A).

I wish I had known this two years ago; could have saved thousands in ground rods for street lighting in LNG plant. thanks again Charlie.

 

[charlie b]

Keep in mind, however, that any number of engineers (sadly, as I must admit), inspectors, and tenants tend to expect there to be a ground rod at all light poles. Many standard design drawings show the ground rod. Several years ago, an "owner's representative," who was an EE, told me to add a ground rod to my design drawings. I pointed out that it was not required and that it can have no impact whatsoever on safety. His reply: "Yea, I know. But I want it anyway." I think there is a general fear that if a person receives a shock from touching a light pole that did not have a ground rod, the blame will come back to the engineer or the electrical contractor for failure to add the ground rod. The fact, and I do mean FACT, that had a ground rod been present the person would still have received the shock, does not seem to be able to break through their preconceived (and inaccurate) notions of how electricity works.

 

[Isaiah]

Keep in mind, however, that any number of engineers (sadly, as I must admit), inspectors, and tenants tend to expect there to be a ground rod at all light poles. Many standard design drawings show the ground rod. Several years ago, an "owner's representative," who was an EE, told me to add a ground rod to my design drawings. I pointed out that it was not required and that it can have no impact whatsoever on safety. His reply: "Yea, I know. But I want it anyway." I think there is a general fear that if a person receives a shock from touching a light pole that did not have a ground rod, the blame will come back to the engineer or the electrical contractor for failure to add the ground rod. The fact, and I do mean FACT, that had a ground rod been present the person would still have received the shock, does not seem to be able to break through their preconceived (and inaccurate) notions of how electricity works.

Excellent point Charlie; believe me, I know the feeling. Perceptions seems to over ride technical fact, especially when it comes to grounding and bonding.