Cell Tower Service grounding

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bonovox

New member
Location
New Jersey
Gentlemen, I'm in the process of changing the service at a cell tower site. There is presently two service laterals. I am replacing these with a 400A meter stack and refeeding these existing panels. There is no water pipe or building steel at the site. There is a #2 solid copper? ground ring? around the site, which I believe, is intended for lightening and it does not appear to meet the requirement of being 30" deep. My question is would I be wrong in sizing my GEC per 250.66 and then bond to the #2 copper per 250.106
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: Cell Tower Service grounding

Do not have a code book handy at the moment, but it sounds correct.

Is the a exposed copper bus on the wall or a bus where the coaxes enter the building? These buses should be bonded to the ring also.
 

websparky

Senior Member
Location
Cleveland, Ohio
Re: Cell Tower Service grounding

2002 NEC 250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(4) Ground Ring. A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 2 AWG.

250.66 Size of Alternating-Current Grounding Electrode Conductor.
(C) Connections to Ground Rings. Where the grounding electrode conductor is connected to a ground ring as permitted in 250.52(4), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than the conductor used for the ground ring.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: Cell Tower Service grounding

If the existing ring is not at least 30" deep, it is not a grounding electrode per the code. You will have to provide your own grounding electrode and bond the ring to your electrode.
Don
 
Re: Cell Tower Service grounding

We do quite a bit of work for a large wireless telecommunications company. Their standard is to use a continuous #2 tinned bare copper wire (minimum 30? below grade) around the entire building with ground rods every 10-16 feet. Both ends of this wire terminate on a 4? x 48? x ?? Ground Bus with 2-hole compression lugs. All other grounding connections within the building originate from this bus. Since our Grounding electrode conductor for the service entrance connects to this bus bar rather than directly to the ground ring, I have always sized the GEC by 250.66 (larger than the #2 bare for any service size over 250A). I do, however, also run a conductor (same size as the GEC) to building steel and under ground water pipe.
 
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