ground rod for light pole

[cutekennydet]

I have read previous post saying it is not a NEC
requirement to install ground rods at each light pole.However, the AHJ is asking for them. My question is on the instalation of the Ground rods. The excva. guy made the form hole 10ft deep. Do I put the rod inside or outside of the form ? Does the rod have to touch soil or can it be completely in the concrete 8ft rod 10ft hole.
I normally do residential and have never done this so please tell me inside or outside of the concrete. Thanks

 

[ryan_618]

Re: ground rod for light pole

There should be a detail on your plan that shows it. if it is not on the plan (or otherwise required by the engineer), your AHJ is acting beyond the scope of his job and his/her bluff should be called. It is not an NEC requirement.

 

[dereckbc]

Re: ground rod for light pole

I agree with Ryan that it is not a code requirement. However contact the design engineer. The designs I have issued call out for the rod to extend below the form, in direct contact with earth. and the GEC welded to the re-enforcement bars as it passes through the center of the form, called a Ufer.

It is a design issue, not code

 

[cutekennydet]

Re: ground rod for light pole

It is not on the plan. What is the common detail?

 

[dereckbc]

Re: ground rod for light pole

There is no detail per NEC. Call your design engineer.

 

[dereckbc]

Re: ground rod for light pole

If I were to design it, I would drive the rod in the bottom of the hole and run the bonding jumper through the center of the form and cadweld/bond/connect to re-enforcing bar along the way. In addition I would make sure the concrete guys doulbe tie or spot weld all re-bar connections.

 

[cutekennydet]

Re: ground rod for light pole

Thanks Guys, I will call the insp on this in the morning maybe he will back down.

 

[tom baker]

Re: ground rod for light pole

Ask the AHJ to cite you a code rule. there is not one. And find out what he feels the ground rod will accomplish:
1. It will not protect the luminaire from lightning damage
2. It will not reduce step potential in the event that the pole is energized from a line to ground fault.
3. It will not clear a line to ground fault if no equipment grounding conductor is installed.
4. It will not protect the concrete foundation from damage in the event of a lightning strike. the concrete won't be damaged anyway.

If the inspector believes it will do any of the above, Mike Holt would like to hear from him, but only if he has proof. its mike@mikeholt.com

Intstalling ground rods at metal lighting poles for the above reasons is a waste of time.

However, ground rods are usefull if its a time and materials job.

[ December 10, 2003, 12:16 AM: Message edited by: tom baker ]

 

[jcook980]

Re: ground rod for light pole

I strongly recommend attending one of Mike Holt's grounding and bonding classes as I did two months ago here in Oregon. Mike is a dynamic and engaging teacher and explains with absolute clarity why ground rods at light poles serve no useful purpose. Even worse, they lead to fatal assumptions that they improve the safety of the installation. Tom cites the most common excuses for requiring a light pole ground rod (I love the T&M comment, Tom!).

 

[pierre]

Re: ground rod for light pole

Dereck
My following comment has no disrespect for you, I believe you are one of the more intellegent people I have met (posted to).

Tom and Jcook have both said most of how I feel about the grounding electrode at a light pole. The poster mentioned ten feet of concrete. That in itself is much better as an electrode than an additional groundrod, which at that point is a waste of time and money. The money could be better spent elsewhere.
Jcook's comment about the false sense of safety some feel when they see a 'lightning rod' at a pole is what I feel most strongly about.

Dereck the one thing I would EMPHASIZE if the 'lightning rod' is installed, is to make a solid connection of the equipment grounding conductor (that should be run with the circuit conductors) to the the grounding electrode conductor. That seems to me to be the most important part of the installation!

If you are looking for the code reference for this type of ground rod it is 250.54 and it is not required. I myself would ask for it in writing from the inspector - I wonder what else he asks for.

Pierre

 

[dereckbc]

Re: ground rod for light pole

Pierre, no offense taken. I agree with what has been said. I wouldn't install a rod for a light pole installed in this fashion.

In cases where I have had to install rods on towers, building foundations, etc that are under millitary contract, that is the way to construct a Ufer. Just passing on experience.

 

[chaos5505]

Re: ground rod for light pole

It sounds like the designer is installing these ground rods for lightning protection and as we all know, he cant do it that way. Why is he not grounding these poles using the circuit grounding conductor and bonding to each pole as he goes?

There should be some detail or specs concerning this.

 

[steve66]

Re: ground rod for light pole

If you ran an equipment grounding conductor with the branch circuit, and each pole is fed from only one branch circuit, the ground rod is not required. See the exception to 250.32(A). I believe a light pole is considered a "separate building or structure".

If you did not run a EGC, well, I will assume you did since the conduit is probably PVC.

STeve