# Grounding of light pole foundations?



## daveco

Can anyone help me with what's the latest on grounding of a parking lot light foundation? I'm replacing one that was snapped off and I searched the code for it.... but of course the code book is not designed for simplification of finding something that could save a life... (that's a whole nother topic!!)

30 years in the trade and I've seen several ways of grounding and not grounding and don't have the time or energy to waste time looking anymore since it's only one base replacement.

Thanks,

Daveco


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## BuzzKill

The code book is pretty simple; regardless, set a rod at each pole, and also bond the GE that comes with the conductor/switch leg.


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## Bob Badger

It's already in the ground isn't it?

As far as the NEC is concerned just run an EGC with the circuit conductors to the site pole and you are done.

Anything else is by choice or job spec.


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## BuzzKill

Bob Badger said:


> It's already in the ground isn't it?
> 
> As far as the NEC is concerned just run an EGC with the circuit conductors to the site pole and you are done.
> 
> Anything else is by choice or job spec.


no rod?
I've seen them here, must be a AHJ thing...


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## Bob Badger

BuzzKill said:


> The code book is pretty simple; regardless, set a rod at each pole, and also bond the GE that comes with the conductor/switch leg.


That could be required if the pole was supplied by a feeder or more than one branch circuit.

250.32(A)


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## Bob Badger

BuzzKill said:


> no rod?
> I've seen them here, must be a AHJ thing...


Many job specifications we get require ground rods at site poles. IMO it is ridiculous to think an 8' x 1/2" rod is going to 'connect' the site pole to earth anymore then the large concrete base already in the earth.


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## BuzzKill

Bob Badger said:


> That could be required if the pole was supplied by a feeder or more than one branch circuit.
> 
> 250.32(A)


a pole light counts as a "building or structure"?
that sounds arguable if that's the best ref.


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## BuzzKill

Bob Badger said:


> Many job specifications we get require ground rods at site poles. IMO it is ridiculous to think an 8' x 1/2" rod is going to 'connect' the site pole to earth anymore then the large concrete base already in the earth.


I disagree, for once, with you; the rod will definitely help in the event of a lightning strike...I bet BrianJohn knows of some studies on this.


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## daveco

I'm with you Bob. The concrete encased rebar six foot in the ground IS an electrode. I see though that it's still a frequently confusing topic and wanted to see if it was ever cleared up.

Dave


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## BuzzKill

daveco said:


> I'm with you Bob. The concrete encased rebar six foot in the ground IS an electrode. I see though that it's still a frequently confusing topic and wanted to see if it was ever cleared up.
> 
> Dave


I'd agree as long as the EGC is bonded to the footer, pole and the switch leg G.


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## NolaTigaBait

BuzzKill said:


> I'd agree as long as the EGC is bonded to the footer, pole and the switch leg G.


???:001_huh:


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## BuzzKill

NolaTigaBait said:


> ???:001_huh:


what now?


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## Bkessler

I worked for a contractor in Michigan that did a lot light poles and we put a ground rod in each one, Now in California I used to do a lot of school and have never installed a ground rod at a light pole.


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## 480sparky

BuzzKill said:


> what now?



What is a "switch leg G"?


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## BuzzKill

480sparky said:


> What is a "switch leg G"?


hm, the G wire, ground wire, green one.


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## BuzzKill

okay I get it I repeated myself,,,whatever, drrrr.


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## 480sparky

BuzzKill said:


> hm, the G wire, ground wire, green one.



OK, so now why are you switching it? :001_huh:


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## BuzzKill

BuzzKill said:


> I'd agree as long as the EGC is bonded to the footer, pole and the switch leg G.


switch what?


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## 480sparky

BuzzKill said:


> switch what?



The Switch Leg G.


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## BuzzKill

just ground/bond everything


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## daveco

Ok, thanks everyone... I think I have my answer. I just do what ever I feel is best ;-) It doesn't seem to be in the code except for those inspectors that "think" it is under their jurisdiction to make it so.

The pole that I'm replacing never had any grounding. It didn't even utilize and Equipment Ground. But then, it never had any rebar in it either and the base was only 12" in diameter for a 20ft pole, so they were probably not going by any specs at all. Anything I do will be better than what was there.

Thanks,

Dave


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## nitro71

Unless there is a local code or engineering spec requiring a ground rod the NEC does not require them for light poles. That's my stance on them. If not required I'm not a engineer and see no reason to put one in.

You do need to get that EGC in there. That is a a safety issue and a direct code violation to not have a EGC.


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## Bob Badger

BuzzKill said:


> a pole light counts as a "building or structure"?
> that sounds arguable if that's the best ref.


Not arguable, to the NEC the light pole and base is a structure.

Here is the definition from article 100



> *Structure.* That which is built or constructed.


Pretty much covers anything that does not come from a seed or egg or the dirt.


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## Mastertorturer

*Contact with earth or driving a ground rod will not protect conductors to the equipment nor will it protect people from shock who touch the light post!*

*"Electricity does not seek the path of least resistance to the earth.* It seeks all available paths back to it’s source, in proportion to their resistance. The reason that a person gets shocked when touching an ungrounded conductor and the earth is because the neutral of the system is repeatedly connected to earth in a grounded electrical system. The earth becomes part of a return path to the transformer – it’s part of one route back to the source; the earth is not the destination for the electricity"

*"Driving a ground rod to ‘ground’ any electrical equipment does not provide the low-resistance path required to trip breakers.* Driving a ground rod, or using a Ufer, or a metal water pipe is not a substitute for an EGC. A ground rod with 25 ohms to earth will allow almost five amps to escape the system into the earth when directly energized from a 120V source. Five amps will never trip a 15A or 20A breaker, and in the meantime everything bonded to this ground rod will be energized to 120V."


http://forums.mikeholt.com/showthread.php?t=95495


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## brian john

Bob Badger said:


> Many job specifications we get require ground rods at site poles. IMO it is ridiculous to think an 8' x 1/2" rod is going to 'connect' the site pole to earth anymore then the large concrete base already in the earth.


Yeah a ufer at the house and a rod at a concrete base??????????? I'd bet the base test lower than a single rod.


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## brian john

mastertorturer said:


> *contact with earth or driving a ground rod will not protect conductors to the equipment nor will it protect people from shock who touch the light post!*
> 
> *"electricity does not seek the path of least resistance to the earth.* it seeks all available paths back to it’s source, in proportion to their resistance. The reason that a person gets shocked when touching an ungrounded conductor and the earth is because the neutral of the system is repeatedly connected to earth in a grounded electrical system. The earth becomes part of a return path to the transformer – it’s part of one route back to the source; the earth is not the destination for the electricity"
> 
> *"driving a ground rod to ‘ground’ any electrical equipment does not provide the low-resistance path required to trip breakers.* driving a ground rod, or using a ufer, or a metal water pipe is not a substitute for an egc. A ground rod with 25 ohms to earth will allow almost five amps to escape the system into the earth when directly energized from a 120v source. Five amps will never trip a 15a or 20a breaker, and in the meantime everything bonded to this ground rod will be energized to 120v."
> 
> 
> http://forums.mikeholt.com/showthread.php?t=95495


*why are you screaming?*

*rods are generally driven for lightning protection at poles not in place of egc's*

So what's your point?


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## brian john

daveco said:


> Can anyone help me with what's the latest on grounding of a parking lot light foundation? I'm replacing one that was snapped off and I searched the code for it.... but of course the code book is not designed for simplification of finding something that could save a life... (that's a whole nother topic!!)
> 
> 30 years in the trade and I've seen several ways of grounding and not grounding and don't have the time or energy to waste time looking anymore since it's only one base replacement.
> 
> Thanks,
> 
> Daveco


Two suggestions
Get the Soares book on grounding and a NEC Handbook and your troubles will be over.

http://www.contractor-books.com/IA/2008_Soares.htm


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## nitro71

The only issue I have with considering a light pole a structure is by that definition everything is. Weatherproof receps on a perma post or anything. Seems that part of the code needs re-defined.


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## Mastertorturer

brian john said:


> *why are you screaming?*
> 
> *rods are generally driven for lightning protection at poles not in place of egc's*
> 
> So what's your point?


The point was to get people's attention.

Bonding of the Light post must be seperate from a Lightning Arrestor. Attaching a ground rod of any kind to the foundation of the lamp post or metal frame would be incorrect.

The whole point of bonding is to give a low impedence path back to the source. Just getting the information out there is all.


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## The Lightman

Mastertorturer said:


> A ground rod with 25 ohms to earth will allow almost five amps to escape the system into the earth when directly energized from a 120V source. Five amps will never trip a 15A or 20A breaker, and in the meantime everything bonded to this ground rod will be energized to 12


Energized poles are no fun. I repaired a short in a fixture on a pole that was centered on the door of a grocery store. I was removing the hand hole cover at night and the arc from the bolt to my nut driver was the first clue. It turned out a wire nut melted over the reflector and was shorted to it and the whole pole was energized.


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## Bob Badger

Mastertorturer said:


> Attaching a ground rod of any kind to the foundation of the lamp post or metal frame would be incorrect.


It is done all the time and while I do not see a benefit it is not 'incorrect' or hazardous.


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## Bob Badger

nitro71 said:


> The only issue I have with considering a light pole a structure is by that definition everything is. Weatherproof receps on a perma post or anything.


I agree, if it did not grow there it is a structure to the NEC and most building codes use the same or similar defintion of structure.

There is a reason the NEC uses the both 'buildings' and 'structures' and the reason seems to be that they want it to apply to more than just buildings.




> Seems that part of the code needs re-defined.


What part of that code is causing a problem?


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## brian john

Mastertorturer said:


> The point was to get people's attention.
> 
> Bonding of the Light post must be seperate from a Lightning Arrestor. Attaching a ground rod of any kind to the foundation of the lamp post or metal frame would be incorrect.


As noted by others this is done all the tiime a waste of an 8' rod in my opinion but done and there is nothing wrong with it or illegal as far as I can see. What is the difference between a concrete base (basically a Ufer by default) and adding an additional electrode?



> The whole point of bonding is to give a low impedence path back to the source. Just getting the information out there is all.


This discussion as I see it has nothing to to with the EGC back to the supply service that is a seperate issue and is mandatory. This supplemental rod is not per design (for the jobs I have worked on) have anything to do with serving as a fault path for the distribution wiring.


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## Bob Badger

brian john said:


> This supplemental rod is not per design (for the jobs I have worked on) have anything to do with serving as a fault path for the distribution wiring.


AKA 'The grounding voodoo rod' , it is simply an offering to the Gods of lightning in the hopes to save the light pole ........ and it will not. :jester:


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## jwjrw

Bob Badger said:


> AKA 'The grounding voodoo rod' , it is simply an offering to the Gods of lightning in the hopes to save the light pole ........ and it will not. :jester:


 

Seems like all engineers have the thought that the more grounding the better.


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## RIVETER

Bob Badger said:


> AKA 'The grounding voodoo rod' , it is simply an offering to the Gods of lightning in the hopes to save the light pole ........ and it will not. :jester:


The way things are going we may have to drive a ground rod at each tree. They seem to get struck a lot.


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## nitro71

Bob Badger said:


> What part of that code is causing a problem?


The only thing I see get ground rods as structures are ones that get feeders to them and have sub panels in my neck of the woods. Was just thinking some clarifying of whether it is the NEC's intent for us to use ground rods at light poles and which structures require them and those that dont.


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## RIVETER

In my opinion and it is just an opinion, there is a need for a grounding rod at a lighting pole. It does seem redundant to the "ufer" created by the pole foundation but it goes deeper into more moist ground. The other reason is that if a hit does occur at the pole the strike current has a lesser opportunity to track into the source via the egc. Maybe if an arrester is installed, I'd change my mind.


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## Bob Badger

RIVETER said:


> In my opinion and it is just an opinion, there is a need for a grounding rod at a lighting pole. It does seem redundant to the "ufer" created by the pole foundation but it goes deeper into more moist ground.



It is all about surface area, the surface area of the concrete base is literally thousands of times more than a rod. I agree with Brian, if you tested the base and the rod separately the base would show much lower resistance to ground.


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## RIVETER

Bob Badger said:


> It is all about surface area, the surface area of the concrete base is literally thousands of times more than a rod. I agree with Brian, if you tested the base and the rod separately the base would show much lower resistance to ground.


Maybe so. I am sure that someone, somewhere has done just that test. Maybe they would post the results. Until then, if it's just a money and time issue I'd do it because that is why I would be there.:thumbsup:


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## nitro71

Last year I removed some old light poles that had probably been in for 30 years or more. Didn't see any signs of lightning hits or damage to them. They did not have ground rods driven for them. The tallest one was 25-30', so nothing to excessively tall. I really don't have an opinion on it really. 

Does a good ground(as in real dirt) connection make it so the lighting doesn't differentiate between that tall pole and the dirt next to it? Or does it see it as a taller structure and tend to hit it? I'm not really sure on lightning hitting taller structures more, that's just what I've heard before.


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## RIVETER

nitro71 said:


> Last year I removed some old light poles that had probably been in for 30 years or more. Didn't see any signs of lightning hits or damage to them. They did not have ground rods driven for them. The tallest one was 25-30', so nothing to excessively tall. I really don't have an opinion on it really.
> 
> Does a good ground(as in real dirt) connection make it so the lighting doesn't differentiate between that tall pole and the dirt next to it? Or does it see it as a taller structure and tend to hit it? I'm not really sure on lightning hitting taller structures more, that's just what I've heard before.


As far as I know the lightning strike will just go in the direction of the buildup of the opposite ions. If they are allowed to accumulate they will be on the top of the pole, on the sides, and on the ground of the entire area. the Voltage will attempt to satisfy itself onto and all around the pole. The pole won't take the full surge. What it does take, hopefully will go to ground at the base with whatever the attachment to earth is.


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## kolbychamberlain

can anyone tell me what is the largest wire size to terminate to a ground rod ___Awg?


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## jwjrw

kolbychamberlain said:


> can anyone tell me what is the largest wire size to terminate to a ground rod ___Awg?


 

Is this a school question?


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## 480sparky

kolbychamberlain said:


> can anyone tell me what is the largest wire size to terminate to a ground rod ___Awg?





The size stated somewhere in Article 250.:whistling2:


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## RIVETER

480sparky said:


> The size stated somewhere in Article 250.:whistling2:


That is what I was going to say...somewhere in the code book, right?:blink:


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## 480sparky

If I wanted to get technical, I'd say the largest conductor you could terminate on a ground rod is 2000 kcmil. However, the NEC has a size stated that is the largest required.


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## RIVETER

480sparky said:


> If I wanted to get technical, I'd say the largest conductor you could terminate on a ground rod is 2000 kcmil. However, the NEC has a size stated that is the largest required.


And, you are correct. Specific answers are good.:thumbsup:


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## kolbychamberlain

yes its a school question how does that translate to awg? i have several of these type questions


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## 480sparky

We're not picking on you, Kolby. We just discourage new members from posting homework-type questions. You need to learn to look up the answer yourself.

Let's try this: Where in Art. 250 (which Part #) do you think it would be?


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## kolbychamberlain

can i look up article 250 on the internet?
i dont have a code book


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## 480sparky

kolbychamberlain said:


> can i look up article 250 on the internet?
> i dont have a code book



You can. But it will take a while. In any event, you should learn to use the old-fashioned paper version. For two reasons.

One is, when you're out in the field, you won't be able to fire up your laptop just to look something up. Second, electronic versions aren't allowed for most tests you take.


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## kolbychamberlain

thankyou


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## 480sparky

kolbychamberlain said:


> thankyou



OK, if you must:

NEC online.


Don't say you weren't warned.


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## kolbychamberlain

i found it you are right its a bitch...lol


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## 480sparky

So, back to your question.... which Part of Art. 250 do you think it would be in?


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## lem

Check Mike Holt.com He advises to usr just the egc.


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## macrylinda

BuzzKill said:


> what now?


I worked for a contractor in Michigan that did a lot light poles and we put a ground rod in each one, Now in California I used to do a lot of school and have never installed a ground rod at a light pole.


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## RIVETER

BuzzKill said:


> a pole light counts as a "building or structure"?
> that sounds arguable if that's the best ref.


The grounding is for lightning strikes or some other weird phenomena. If a rod is there, use it, if not, drive one. It doesn't make sense to send a strike current into the building to be nullified. The egc is hooked up normally.


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## Bob Badger

RIVETER said:


> The grounding is for lightning strikes or some other weird phenomena. If a rod is there, use it, if not, drive one. It doesn't make sense to send a strike current into the building to be nullified. The egc is hooked up normally.


So how do the electrons know to take a right and head for the rod and not take a left and head into the building on the EGC?


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## TOOL_5150

Bob Badger said:


> So how do the electrons know to take a right and head for the rod and not take a left and head into the building on the EGC?


Well duh... the "path of least resistance" of course. Everyone knowes that a ground rod is the best path to ground..... :jester:

~Matt


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## BobBob

*Latest*

"what's the latest on grounding of a parking lot light foundation?"


Well, the latest thing I've seen developers do is bond the neutral to the ground rods at poles. That would be latest, obviously dangerous as hell.

BobBob


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