Grounding electrode issue

[usmcgrover]

I have a strange issue here with a grounding electrode.

We have installed a room for an electronics lab. The walls and ceiling of the room were covered in steel mesh before the sheet rock was installed. The lab guys want us to install a copper pipe all the way around the perimeter of the room at the floor to attach "grounds" to. The stated intent of this system is to absorb RF energy for an "RF clean environment" (I wonder if I should mention the electronic ballasts in the light fixtures...)

Anyway, the issue I have with all of this is the way they want to install the grounding electrode for this system. They want the grounding electrode to be installed independently of the rest of the grounding system for the building. I told them that any grounding electrode that is present is required by the NEC to be bonded to the rest of the grounding electrode system per 250.50. They insist that the building steel is too "noisy" for their purposes.

Has anyone else encountered such a situation? I'd appreciate your comments.

Jeff

 

[Dennis Alwon]

I am confused-- are you calling this piping that just covers the perimeter of the room an electrode. If so then I don't think this would qualify as a grounding electrode.

 

[usmcgrover]

Oops

Oops

The grounding electrode will be a 30' ground rod driven into the ground.

 

[e57]

I hope your code book is not on CD - because the printed version works better as a method to get this across to them...

If an electrode is installed it need not get connected to the electrode system. See 250.54
(Article on the topic)

Using a "Pipe" though???

Alternately - offer a complaint grounding means - oh and make it REALLY EXPENSIVE - which is easy to do... Copper buss work... And connect it to the Main Bonding Jumper... Or thier seperate rod if they wish...

You may also want to explain the reasons that copper pipe is no longer suitable as a GEC or EGC - past 5' from underground... The material is a code violation - so alternately an oversized conductor is preferred... Say 750MCM Then to bus work or listed terminal bars for the purpose...

 

[richxtlc]

I believe he means a ground bus (copper pipe) being used for grounding portable equipment on a test bench. I do not believe he is using the grounding bus as a grounding electrode.

 

[usmcgrover]

They want me to install a 30' ground rod for the grounding electrode for this system, not a pipe.

The pipe runs around the inside of the room to provide a point for them to attach "grounds" (not equipment grounds) to reduce noise from RF sources.

 

[usmcgrover]

250.54 answers my question, I just didn't read far enough. Thanks for your replies.

 

[e57]

I believe he means a ground bus (copper pipe) being used for grounding portable equipment on a test bench. I do not believe he is using the grounding bus as a grounding electrode.

A "tubular" bus and "Copper pipe" are two different things over the phone - I argee...

 

[cschmid]

could you not use screw together ground rods and mount them on the interior wall. connect them to a separate rod as this is only for secondary noise and nothing else.