[TowerTalk] Ground Rods

[jimlux]

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?
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