(3) temporary poles, (1) service - do they each need a ground rod?

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Lee Graves

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On a project we're working on, we have (3) temporary poles with feed thru lugs supplied by one service. The poles are ~200' apart. They're 1p 4w. Should each pole get its own ground rod?

The difficult part: We lost (1) hot leg between TP01 and TP02. We are planning to re-phase the neutral conductor and use it as the lost hot leg. We will then re-phase the grounding conductor and use it as the neutral. This means between TP01 and TP02 we will only have a 3W system.

1. When we get to TP02, should we drive a ground rod since there is no grounding conductor being supplied on the line side? (currently the only ground rods are driven at TP01)

2. Should we install a main bonding jumper at TP02?


Thanks for the input,

Lee Graves
 
Lee Graves said:
On a project we're working on, we have (3) temporary poles with feed thru lugs supplied by one service. The poles are ~200' apart. They're 1p 4w. Should each pole get its own ground rod?
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250.32(A) says yes.


The difficult part: We lost (1) hot leg between TP01 and TP02. We are planning to re-phase the neutral conductor and use it as the lost hot leg. We will then re-phase the grounding conductor and use it as the neutral. This means between TP01 and TP02 we will only have a 3W system.
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Just a heads up using a bare for feeder neutral is not always allowed, what wiring method is in use?

1. When we get to TP02, should we drive a ground rod since there is no grounding conductor being supplied on the line side? (currently the only ground rods are driven at TP01)
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Yes, and that applies even if you had the EGC.


2. Should we install a main bonding jumper at TP02?
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Without the EGC running to TP02 you are required by 250.32(B)(2) to install a bonding jumper.
 
250.32(a)

250.32(a)

I don't see how this section applies to temporary poles? We're not supplying a building or structure with a feeder or branch circuit, ...We're just supplying a few GFI receptacles on the side of the pole? Now if we install temporary lights within the building or structure, I guess this rule would apply?
 
Lee Graves said:
I don't see how this section applies to temporary poles?
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Lee, without a doubt a temp pole is a structure.

Take a look at the definition of structure in Article 100.....

Well it's real short so I will type it out.

Structure: That which is built or constructed.
 
Lee, without a doubt a temp pole is a structure.

Take a look at the definition of structure in Article 100.....

Well it's real short so I will type it out.

Structure: That which is built or constructed.
Click to expand...



So to backup just a little bit, does each temporary pole need its own disconnecting means since its a 'structure'? We have (3) temp poles, we'll call them TP01, TP02, and TP03. TP01 has a 200A meter and panel with a main breaker. It also has a 60A breaker to feed TP02. TP02 is a main lug only panel with feed thru lugs to feed TP03. TP03 is also a main lug only. Is this installation a violation of the NEC?
 
while i don't disagree that ground rods are required on temp poles, there are only two AHJ's within a 60mi. radius of me that require them, and they are within the same county. they are also the only two that require permits on temp poles. so apparently there are a lot of other people that don't think rods on a temp pole are worth having.
 
Lee Graves said:
It also has a 60A breaker to feed TP02. TP02 is a main lug only panel with feed thru lugs to feed TP03. TP03 is also a main lug only. Is this installation a violation of the NEC?
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Each pole needs its own ground rods and each pole must either have a main disco ( usually a main breaker) or meet the maximum 6 disco rule (usually 6 breakers).
 
cutting ground rods!

cutting ground rods!

Hey walkerj you better not mention cutting rods in here!! Its like Rich suggested. Check out that post!!! It went on for a while! I started to tell Bob that I cut so many rods that I had to buy a chop-saw!! With the 2 rod requirement it paid for the saw fast. According to how short you cut 'em you can get several services out of one rod!!!
 
Lee Graves said:
I don't see how this section applies to temporary poles? We're not supplying a building or structure with a feeder or branch circuit, ...We're just supplying a few GFI receptacles on the side of the pole? Now if we install temporary lights within the building or structure, I guess this rule would apply?
Click to expand...

It helps to understand why we have electrodes. 250-4(A)(1) ?Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, lines surges, or unintentional contact with higher-voltage lines?

In other words the electrode serves no other purpose except to route lightning bolts and such to earth, it is NOT used to route shorts (ground faults) to open circuit breakers 250-4(A)(5).

So the issue is: can this pole be struck by lighting? And the answer is obviously yes.
 
tryinghard said:
So the issue is: can this pole be struck by lighting? And the answer is obviously yes.
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But that lightning risk doesn't matter if the pole is served by a single branch circuit? It doesn't matter to a 50' steel light pole served by a single circuit? :)

I think 250.32 is an oversimplification for simplicity's sake - as awkward as the position may be, I'd keep driving ground rods at these wood temp poles than to try to complicate the wording to exclude them. I kinda wonder if the CMP's take is the same.

Edit to add: Lee, take a look at this. I wouldn't worry about it in the application you're talking about (temp), but worth considering in the future to avoid a tag, IMO.
 
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georgestolz said:
But that lightning risk doesn't matter if the pole is served by a single branch circuit? It doesn't matter to a 50' steel light pole served by a single circuit? :)

I think 250.32 is an oversimplification for simplicity's sake - as awkward as the position may be, I'd keep driving ground rods at these wood temp poles than to try to complicate the wording to exclude them. I kinda wonder if the CMP's take is the same.
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George I?m not sure what you mean? I understand Lee as trying to justify not installing electrodes at each pole [structure] and with this my site #11 is used to help advise him to install the electrodes at each pole.
 
tryinghard said:
George I?m not sure what you mean?
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What I meant is, the NEC is written such that there is a line drawn between a pole served by a feeder, as opposed tp a branch circuit, that's all. I wasn't taking issue with your reply - I was just noting that I believed you were attributing more sense to 250.32(A) than it probably deserves. :)
 
georgestolz said:
But that lightning risk doesn't matter if the pole is served by a single branch circuit? It doesn't matter to a 50' steel light pole served by a single circuit? :) IMO.
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George this is not Lee?s case he?s feeding. And I know you know this but not having an electrode is an exception not the rule so it may not be required on branch but installed anyway. Often light poles do bond to cages with [or without] electrodes so if hit by lightning the lightning will travel the shortest distance possible to ground rather than throughout the equipment grounding system.

georgestolz said:
What I meant is, the NEC is written such that there is a line drawn between a pole served by a feeder, as opposed tp a branch circuit, that's all. I wasn't taking issue with your reply - I was just noting that I believed you were attributing more sense to 250.32(A) than it probably deserves.
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I appreciate your comments and take no offense to them at all but I actually haven?t stated 250-32 in this post yet but it really does apply to Lee?s application.

He?s feeding so: an electrode is required at each pole (structure), all these electrodes are required to be bonded together, and if he does not have any other metallic paths between these poles ? temp power poles usually don?t ? and there?s no ground fault protection at the service disconnect then he can use the neutral for the electrode bonding qualifying a 1ph 3w circuit meaning 250-32(B)(2) certainly applies.:)
 
Around here, in the past is was common practice to use a "butt wrap" for the grounding electrode on a temporary service or power pole. I don't think that was ever permitted by the code...unless you wrapped 20' of #4 around the bottom of the pole...(a ground ring).
Don
 
tryinghard said:
I appreciate your comments and take no offense to them at all...
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That's good to hear. :cool:
...an electrode is required at each pole (structure)...
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Agreed.

...all these electrodes are required to be bonded together...
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Huh? Between the different poles? I'd disagree with that.

...and if he does not have any other metallic paths between these poles ? temp power poles usually don?t ? and there?s no ground fault protection at the service disconnect then he can use the neutral for the electrode bonding qualifying a 1ph 3w circuit meaning 250-32(B)(2) certainly applies.:)
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I would agree with that. :)
 
georgestolz said:
tryinghard said:
...all these electrodes are required to be bonded together...
Click to expand...

Huh? Between the different poles? I'd disagree with that.

:)
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How so?

These poles are fed from one common service (250-32(A)), so this application really is an ?either or? type meaning:
either
?An equipment grounding conductor?shall be run with the supply conductors and connected to the?grounding electrode(s)? (250-32(B)(1))
or
?the [neutral] conductor run with the supply to the [pole] shall be connected to the?grounding electrode(s)? (250-32(B)(2))
 
Well, that's like saying that all of the structures have to have their weight supported by the ground - yes, it's true, but it's not something that takes conscious effort. The statement "all electrodes shall be bonded together between structures" sounds like a dedicated bonding jumper would be installed to accomplish that, and that is incorrect.

I mean, several houses along the street may be fed from the same utility transformer, and as a result their electrodes are incidentally bonded together - but there's not a requirement to intentionally do that.
 
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