# parking lot pole grounding



## donselec (May 7, 2011)

can soneone point me to the article for pole grounding. do i need to drive a rod at each pole ?

thanks


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## Dennis Alwon (May 9, 2009)

donselec said:


> can soneone point me to the article for pole grounding. do i need to drive a rod at each pole ?
> 
> thanks


No but some engineers draw it in the plans.


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## 480sparky (Sep 20, 2007)

They are not required by the NEC, nor can a ground rod be used as the sole means to ground the pole.


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## RIVETER (Sep 26, 2009)

Okay, the NEC may not require that you "GROUND" a lighting pole. It may be because the pole...if of a certain height and weight, and means of attachment to the "dirt", at it's base, would already be in intimate contact with the earth. I would agree with that.


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## erics37 (May 7, 2009)

donselec said:


> can soneone point me to the article for pole grounding. do i need to drive a rod at each pole ?
> 
> thanks


Pole grounding = install a properly sized equipment grounding conductor with your circuit conductors and *bond* it to the pole. Bond it to the fixture heads too; I wouldn't trust a couple of rusty set screws to make a connection. That's it, that's the final story.

You may install a ground rod at each pole if you wish, and bond it to the equipment grounding conductor that you installed. This will be an auxiliary grounding electrode. It's also largely a waste of time in my opinion.


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## 480sparky (Sep 20, 2007)

erics37 said:


> .......... It's also largely a waste of time in my opinion.


It's not a waste of time if it's spec'd that way and you get paid to do it, regardless of whether it does any good.


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## erics37 (May 7, 2009)

480sparky said:


> It's not a waste of time if it's spec'd that way and you get paid to do it, regardless of whether it does any good.


Indeed. I've never seen it spec'd personally, but from all y'all, I'm sure it is sometimes and somewheres.

However, given what the OP's question is, I doubt there's any job specs for the pole lights.


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## BBQ (Nov 16, 2010)

RIVETER said:


> Okay, the NEC may not require that you "GROUND" a lighting pole. It may be because the pole...if of a certain height and weight, and means of attachment to the "dirt", at it's base, would already be in intimate contact with the earth. I would agree with that.


Do you own an NEC?


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## chicken steve (Mar 22, 2011)

erics37 said:


> You may install a ground rod at each pole if you wish, and bond it to the equipment grounding conductor that you installed. This will be an *auxiliary grounding electrode*. It's also largely a waste of time in my opinion.


 
This is where it gets_ interesting_ , at least in terms of _theory_ Eric

One can have as many aux. grounding electrodes as one desires

but what if those electrodes are spread out, number more than any other electrode, and possibly attach to other structures?

~CS~


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## 480sparky (Sep 20, 2007)

erics37 said:


> Indeed. I've never seen it spec'd personally, but from all y'all, I'm sure it is sometimes and somewheres.
> 
> However, given what the OP's question is, I doubt there's any job specs for the pole lights.


Typically, it's merely copied from an existing set of specs to the next. Once an architect or EE has requested them, it gets carried over to the next job that has light poles.

I think there's a myth that ground rods at metal light poles somehow reduces lightning strikes, or mitigates the damage they will cause, when a rod is installed at the pole base.


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## brian john (Mar 11, 2007)

chicken steve said:


> This is where it gets_ interesting_ , at least in terms of _theory_ Eric
> 
> One can have as many aux. grounding electrodes as one desires
> 
> ...


 
So what is the theory?


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## Big John (May 23, 2010)

480sparky said:


> ...I think there's a myth that ground rods at metal light poles somehow reduces lightning strikes, or mitigates the damage they will cause, when a rod is installed at the pole base.


 Even if it did, the base is already a fantastic Ufer and one silly piece of copper ain't gonna be much improvement.

-John


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## Mr Rewire (Jan 15, 2011)

I remember a thread where they were arguing if a pole was a "structure" and required a ground rod.


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## joethemechanic (Sep 21, 2011)

I like to use these, but I usually don't have them when I need them. So the bottom of the pole gets a spiral of copper wire stapled to it


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## jmsmith (Sep 10, 2011)

Where I've seen bonding in the specs, it involved having a "grounding grid" or no. 2 bare braided buried conductor, to which a no. 4 whip was cad-welded at each pole location. This whip was to be brought-up alongside the pad then connected straight to the post via either a lug or cad-weld, depending on what the spec called-for.

Sent from my iPhone using ET Forum


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## Dennis Alwon (May 9, 2009)

RIVETER said:


> Okay, the NEC may not require that you "GROUND" a lighting pole. It may be because the pole...if of a certain height and weight, and means of attachment to the "dirt", at it's base, would already be in intimate contact with the earth. I would agree with that.


The NEC does require you to ground the pole. It does nor require you to drive a ground rod. A rod doesn't do anything in terms of grounding. A ground rod will only help with lightning and surges- not an NEC issue.


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## Dennis Alwon (May 9, 2009)

Mr Rewire said:


> I remember a thread where they were arguing if a pole was a "structure" and required a ground rod.


IMO, It is a structure but if it is fed with one branch circuit then no rod is required. I am not sure if there is somewhere in the code that exempts us from having a disconnect at the pole. I say that cause you never see one.


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## chicken steve (Mar 22, 2011)

brian john said:


> So what is the theory?


 
i can't say John

i can only conjecture

so there's a mass of electrodes that collectively have a better Z to ground than the _'main electrodes' _

so they mitgate a lighning strike _better_

how that theoretically adds up against an NEC application is a curiousity i would_ dearly_ like others to opine on

~CS~


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## jmsmith (Sep 10, 2011)

chicken steve said:


> i can't say John
> 
> i can only conjecture
> 
> ...


Is there anyone on the forum that is certified for lightning protection installation? They would probably be able to explain. The bonding that I had seen speced usually dealt with substation construction... Everything metal including fences had to be held to ground potential. The refineries and plants I worked around followed the same guidelines, but to also prevent ANY static charges which could prove to be an ignition source.

Sent from my iPhone using ET Forum


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## electricalperson (Jan 11, 2008)

Dennis Alwon said:


> IMO, It is a structure but if it is fed with one branch circuit then no rod is required. I am not sure if there is somewhere in the code that exempts us from having a disconnect at the pole. I say that cause you never see one.


what if the pole had a receptacle on the side for christmas lights? would you need a ground rod then?


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## swimmer (Mar 19, 2011)

480sparky said:


> Typically, it's merely copied from an existing set of specs to the next. Once an architect or EE has requested them, it gets carried over to the next job that has light poles.
> 
> I think there's a myth that ground rods at metal light poles somehow reduces lightning strikes, or mitigates the damage they will cause, when a rod is installed at the pole base.



I was told, by one of the local inspectors, that cell phone towers are encircled by about a dozen ground rods to mitigate the damage caused by a lightening strike or near strike.


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## Dennis Alwon (May 9, 2009)

electricalperson said:


> what if the pole had a receptacle on the side for christmas lights? would you need a ground rod then?


Well, IMO I could care less but the NEC, IMO states that if the receptacle were from a different source and not part of a mwbc then I say it is a violation. Obviously many inspectors would either turn the other way or not consider it a structure but by definition it is clearly a structure.


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## brian john (Mar 11, 2007)

swimmer said:


> I was told, by one of the local inspectors, that cell phone towers are encircled by about a dozen ground rods to mitigate the damage caused by a lightening strike or near strike.


The tower itself is a giant ufer, in our area the concrete bases are dug 25 feet and poured. The multiple ground rods are driven to help mitigate lighting strikes from entering the facility. Typically the ground ring surrounds the towers and building and often installed in a radiating pattern. The towers are generally located on the highest point in the area (when feasible) and they stick up higher than any surrounding structures. One giant lighting rod.


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## Cletis (Aug 20, 2010)

*Engineer*



brian john said:


> The tower itself is a giant ufer, in our area the concrete bases are dug 25 feet and poured. The multiple ground rods are driven to help mitigate lighting strikes from entering the facility. Typically the ground ring surrounds the towers and building and often installed in a radiating pattern. The towers are generally located on the highest point in the area (when feasible) and they stick up higher than any surrounding structures. One giant lighting rod.


I had an engineer once tell me at job site to set grounds to get rid of dangerous harmonics and also lighting strike dissapation...


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## rdr (Oct 25, 2009)

Once had a job to do 30 some odd poles. They were spec'd to have ground in conduit, #6 bare running outside the conduit (ground loop) as well as every pole have its own ground rod. The pole was to be bonded to the circuit ground as well as be bonded to the rod and the ground loop. Not only that but it HAD to be cadweld. As an employee you can go **** it if they wanna pay for it.....as an EC you can go **** it if they wanna pay for it. :laughing:


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## brian john (Mar 11, 2007)

Cletis said:


> I had an engineer once tell me at job site to set grounds to get rid of dangerous harmonics and also lighting strike dissapation...


He is half right any chance you can get 1/2 your money back from him?


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## Cletis (Aug 20, 2010)

I knew he was full of crap from all your harmonic disappation disputing over the last couple years


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## jmsmith (Sep 10, 2011)

brian john said:


> He is half right any chance you can get 1/2 your money back from him?


Until I let my license expire (accidentally..will test again one day for it), I was involved in ham radio. At some of the lower frequencies we used to deliberately isolate a tower from ground to make it one-half wavelength. The other half-wave was usually formed by the actual base plate with wire radials cut to length to total the tower height. This formed the equivalent of a ground- plane antenna. A lot it older AM radio and TV stations treated their "antennas" in the same way. Lightning protection was just an added "bonus" to this set-up. Traditional antennas get far to large at the lower freqs, especially at the power levels involved when you start talking 3000 watts on up.


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