2 grounding electrodes - how to bond?

[StevenMark]

OK, everone's favorite subject: Grounding

My dish antenna and grounding block are mounted about 50 feet from the grounding electrode for my electrical service. Since this exceeds the 25-foot rule for the the ground wire run I added an electrode just below the dish and ran #10 copper from the ground block and dish to the rod. Now, I'm trying to figure out the best way to bond the two electrodes together.

The easiest and cleanest looking way would be to run a green #6 (THHN/THWN) along with my coax into the attic, then over to the service panel. That would bond both rods together since they would share a common grounding block inside the panel. The coax is in PVC conduit outdoors, except for about 3 feet for a drip loop and grounding block. Would this comply with code?

 

[SmityWhity]

I believe it's safe to say that most jurisdictions have adopted the National Electrical Code, but that doesn't mean additional requirements have not been adopted by the State, County/Parish, and/or City.

Here's info to make you sleep better while not watching TV.
http://www.dbsinstall.com/whatis/Whatisgood-5.asp

 

[Todd Humphrey]

There are two ways you could have done this. The NEC, which may or may not be used "as is" in your area, requires you bond those rods together with #6.

Here is my take on the NEC as it applies to this issue. The 20 foot restriction is when using #10. What if you used a larger ground wire? What if you ran a #8? Should you not be allowed to exceed that 20' while maintaining a ground system equal in protection ability? I asked my local electrical inspector and he determined that installing #8 should be just fine for up to 30' and using #6 for up to 40', and using #4 up to 80'. Each of these lengths have a DC resistance of approx .002 Ohms resistance, which is the approx resistance of 20 of #10 solid copper.

Of course you must balance the cost of using #4 vs installing a rod and using #6 to bond.

The other choice to route the coax lines closer to the ground.

 

[Mike500]

An 8 foot long UL listed electrode burried completely connected to the original electrode with a #6 conductor (bare is code compliant) with UL listed direct burial electrodes, complies with any current code. Because it is #6, it is not required to be encased in a protective conduit. The 25 ohm earth resistance requirement only refers to the main electrode. Adding a second electrode alieviates the 25 ohm reuiirement. The bonding conductor should be outside of the structure or at least pass through or be placed in contact with a non-combustible material. That means masonary or earth. Wood or drywall board, unless fire rated, is not a non-combustible material.

In the case of the #6 conductor, burial depth is not important. It can be only 6 inches below the surface.

 

[StevenMark]

Thanks guys. Since I already have the 2nd rod installed (and a 500 foot spool of #6 for another project I'm working on), I'll bond 2 rods rather than run a larger grounding conductor in a single rod system. I figure I'll route the jumper outside the building since that's probably a bit more kosher because of the 'combustable materials' clause. Sure wish my arrangement looked like Mike500's avatar - grounding would be a lot simpler!