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Length between communications ground rod & service ground rods 800.93 810.21

Length between communications ground rod & service ground rods 800.93 810.21

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  #1  
Old 03-03-15, 10:23 AM
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Length between communications ground rod & service ground rods 800.93 810.21

I have a new construction home that the satelite/cable/telephone enter at the complete opposite side from the electrical service. This is home is all electric no gas and ran completely in pex plumbing. Needless to say I cannot bond to the electrical service within 20' so I am going to have to drive a ground rod. The 6awg wire that I bond this ground rod back to the ground rods next to the electrical service is where my questions are. Is there a maxium length of the 6awg wire that I run from the communications ground rod back to the main ground rods? It will have to be buried approximately 140' with 3 - 90 degree turns to get it back to the main service entrance. I have not seen anything limiting the length but this is a long distance and was curious if I skipped anything in my readings? Also are the bends of any concern here I can make them sweeping 90's but they are there.

810.21
800.93
 
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  #2  
Old 03-03-15, 04:33 PM
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Drive the ground rods as is customary for the electric service.

Attach a grounding bridge for electronic equipment to the grounding electrode conductor running between the panel and the ground rods.

Connect the satellite dish, phone, etc. ground wires to the grounding bridge. These wires may be as long as needed. Do not make sharp bends in any of these ground wires, for example use a "tin can" to form curves of about a 1-1/2 inch minimum radius in the wire.

Alternate: Drive an additional ground rod where convenient and recommended for the telephone, etc. Run #6 copper, again with no length limit and no sharp bends, from this ground rod to the other ground rods. Connect the grounding bridge near the additional ground rod for attaching the ground wires from the satellite dish, etc.

All ground rods must be interconnected using #6 copper wire as grounding electrode conductor except that such interconnections that have to cross the lawn, walkway, etc. to get to a different building or structure may be omitted. In the latter case, the equipment grounding conductors in power feeds will suffice as the needed grounding between the structures.

Some experts do not like having ground rods at both ends of the house, hence the first method of running the (usually #8 or smaller) ground wires from the satellite dish, etc. to the first set of ground rods near the breaker panel. But this sentiment is inconsistent with the requirement in some cases of having an additional ground rod at a separate structure.
 

Last edited by AllanJ; 03-03-15 at 05:29 PM.
  #3  
Old 03-03-15, 06:57 PM
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Ok I appreciate the input! I'm sure the satelite cable or phone contractors will not run a ground wire 140' to the service entrance so I am going to drive a ground rod and run a 6 awg to the service gec. I just wasn't sure if there was a length limit on that which you answered, again much appreciated.
 
  #4  
Old 03-04-15, 06:17 AM
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Just to add a little around the subject, if this was a commercial installation with such a distance between the rods we would probably do a ground ring configuration. This is where you take the #6 (or larger in some cases) around the perimeter of the building foundation and drive ground rods every X number of feet, usually something like 10', all bonded to the copper conductor. Generally these details would be specified by an engineer. This is to make sure there are no ground potential gradients around the building that effect communication or compromise lightning protection. I know the spacing of the rods is based on soil conditions, but don't know exactly what formula you would use to calculate it. What you're proposing is a small step in that direction; what I'm not sure of is if two rods over that span is enough.
 
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