[RE-wrenches] rebar v/s fiber

[Kelly Keilwitz, Whidbey Sun & Wind]

As long as the pole surface area required is in earth contact I don't  
see a problem with that. However, our pole mounts are filled to ground  
surface with concrete- usually necessary for foundation strength  
requirements.
If the hole is big we use a rebar mesh cage surrounding the pole. If  
auger-dug w/ less than 6" annulus no rebar. The mesh helps to keep the  
'crete acting as a uniform cohesive block.

Kelly,
from mobile

On Mar 13, 2010, at 13:26, R Ray Walters <ray at solarray.com> wrote:

> Actually my read of 2008 code should allow the pole to qualify as  
> the grounding electrode:
> 690.47 (D) allows the mounting structure to be the electrode if it  
> meets  250.52.
> 250.52(A.7) plate electrode says you need at least 2 sq. ft of 1/4"  
> steel plate.
> A 6" diam pipe 4 ft in the ground, will have 6.8 sq. ft of surface  
> area......
> A 4" diam pole will have 4.7 sq ft of surface area.....
> Anybody see a flaw in this logic?
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
> On Mar 13, 2010, at 1:06 PM, Bob-O Schultze wrote:
>
>> Agreed. I'm surprised that no one mentioned that nice 3'-5' deep  
>> hole is a hell of a nice start for your grounding electrode....
>>
>> On Mar 13, 2010, at 8:30 AM, Kent Osterberg wrote:
>>
>> The need for rebar or not depends on how the pole is secured and on  
>> the shape of the footing.  If you are installing a pipe in a deep  
>> narrow hole per most mount manufacturer's specifications, no rebar  
>> should be necessary.  Anything else will certainly require rebar  
>> and per manufacturers' disclaimers should be designed by an  
>> engineer.  For example, if the installation will have j-bolts in  
>> the concrete with the post welded to a plate held in place by the j- 
>> bolts, a full rebar cage will needed.
>>
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