[TowerTalk] We pour tomorrow - grounding

[K7LXC@aol.com]

In a message dated 10/27/00 1:03:23 AM Pacific Daylight Time, 
conners@teleport.com writes:

> We are pouring the pad for my MA-770 tomorrow afternoon.
>  
>  I have 4 copper ground rods to use to ground the tower. Should I pour the
>  concrete into the hole with the ground rods at each corner or keep them in
>  solid earth.
>  
>  Assuming the answer is keep the ground rods out of the concrete base,
>  please review the following:
>  
>  I have a large excavation with no forms, therefore, no back-filling..Any
>  suggestions as to how to keep the cement from contacting the rods??
>  
>  I cannot simply drive them into the earth after the pour as there is solid
>  basalt at 3 feet.
>  
    The answer to your question is - yes, put one in each corner for a total 
of three (one for each leg) and don't worry about them touching the concrete. 
Concrete is a conductor and it won't hurt anything.

    Four ground rods is only about one per leg - you should have 2 or more 
per leg per industry standards so you need to put in more ground rods. Since 
you can't get down very far, my recommendation is to put them in 
horizontally. You still get a decent contact with earth which is what you're 
trying to do and this will complete the tower portion of the ground system.

    With the cables grounded at the building entry forming a Single Point 
Ground System, you'll be in reasonable shape for lightning protection. More 
info at the Polyphaser website or their new lightning protection book 
(available from http://www.championradio.com).

Cheers,   Steve   K7LXC
Champion Radio Products

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