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[Towertalk] Ground wire impedance

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Subject: [Towertalk] Ground wire impedance
From: (
Date: Tue, 30 Jul 2002 08:32:44 EDT
In a message dated 7/29/02 10:26:52 AM Pacific Daylight Time, writes:

> There seems to be some debate over multiconductor wire for grounding.  As I 
> see 
>  it, the only advantage of stranded cable is mechanical flexibility.  I 
>  think "skin effect" (current flowing on the surface) has much to do with 
>  stranded wire, since the strands are all touching and are all in each 
>  magnetic fields. What is good is to maximize the surface area of the whole 
> cable 
>  -- by making it into thin/wide strap (or hollow tube) instead of a filled 
>  circular cross-section, keeping the same amount of copper per foot.   That 
>  minimizes the inductance.  (Yes, that amounts to the skin effect argument 
>  placing all the copper near the surface of the conductor.)

    Two things. First, stranded wire is NOT acceptable for ground systems. 
Each strand will oxidize and then the strands will be electrically insulated 
from each other. Use solid wire or copper strap only. 

    Next, while the multi-strands do offer more surface area over single 
strand, if you need more earth contact you should use copper strap instead of 
the multi-strand stuff. Using copper strap in rocky or other poor earth 
conditions instead of wire is a good way to improve the effectiveness of a 
potentially poor ground system. Another poor earth technique is to lay ground 
rods horizontally if you can't get them in vertically. 

Steve    K7LXC

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