[TowerTalk] Ground Rods

[Roger (K8RI)]

On 11/30/2010 11:09 PM, jimlux wrote:
> Dan Bookwalter wrote:
>> Ok , i have seen several discussions regarding what people are using for ground
>> rods.... some use actual 5/8" ground rods , while others use 1/2" copper pipe ,
>> thoughts on which is better ?
>>
>> also i was thinking about using 4ft ground rods instead of 8 footers , but use
>> twice as many of them , it is much easier to drive the 4 footers  , thoughts ?
>>
>>
> Why are you driving ground rods at all (not as silly a question as you
> might think)?
>
> Is it for electrical code compliance?
> Is it for lightning grounding?
I find only the first two to be applicable to most tower installations.
I have 32 or 33 8' ground rods cadwelded to a network/grid of over 600 
feet of bare #2 copper.(purchased BEFORE the price went up)
The single point ground for the house/shack is part of this network at 
the entrance bulkhead.

73

Roger (K8RI)

> Is it for RF?
> Is for some other reason, not listed above?
>
> The code has rules about what the electrodes can look like (and a ground
> rod by itself generally can't be the sole grounding means any more).
> The code requires 8 feet in contact with the soil (so that means either
> the rod and connection is buried OR you use a 10 ft rod.)
>
> Buried copper pipe is usually a lot more expensive than a decent copper
> clad steel rod, and harder to drive.
>
> For lightning protection, the goal is to spread the current out.  So if
> you had a choice between 4 rods driven 8 feet deep 10 ft from the tower
> (so they're 14 feet apart) or 8 rods driven 4 feet deep also 10 ft from
> the tower, the more shorter rods is probably better.
>
> Rules of thumb for ground rods:  Space them by at least twice their length
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