[TowerTalk] Screw Anchor Question

[Steve Maki]

Bill Coleman wrote:

>>>Can't one use a sacrificial anode to avoid exactly this sort of
>>>galvanic action?

>>Sure - see:   http://www.anchorguard.com
>>
>>Though it seems like for small towers it would be simpler to just  
>>add an
>>insulator in each guy wire.

> So, how do insulators on the guy wire (especially if the guys are  
> phillystran or fiberglass rod) prevent galvanic corrosion of the guy  
> rod in the earth?
> 
>  From what I understand of reduction-oxidation (redox) reactions,  
> ions in the soil will attack the metal ions in the guy rod just by  
> being in contact.

My limited understanding indicates that the highest current (and 
therefore the worst corrosion) flows between the steel anchors and the 
copper ground system, assuming a reasonable electrolyte (earth). So 
insulating the anchor from the ground system goes a long way toward 
reducing the current in the anchor shaft.

However, according to Anchorguard, even if insulated from the tower the 
anchor shaft can, under some conditions, act as both anode and cathode 
(by  being immersed in dissimilar electrolytes i.e. earth and concrete).

Of course, any piece of metal in the ground can rust....

73,
Steve K8LX