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Re: [RFI] Depth of wires between ground rods?

To: 'Frank O'Donnell' <vfo@inkbox.net>, "rfi@contesting.com" <rfi@contesting.com>
Subject: Re: [RFI] Depth of wires between ground rods?
From: "EDWARDS, EDDIE J via RFI" <rfi@contesting.com>
Reply-to: "EDWARDS, EDDIE J" <eedwards@oppd.com>
Date: Mon, 10 Aug 2020 16:36:21 +0000
List-post: <mailto:rfi@contesting.com>
Depends on a lot of variables, such as site type, rod length, cable size, 
copper vs tinned copper, etc.  Either 24 inch or 30 inch depth seem the two 
possibilities.  I'd go 30" on tower rings and 24" around the home.  But others 
may interpret differently. 

R-56 (based on NEC/NFPA70) states:
>From section Light Duty (Type A) sites (2017 "-C" rev):  
At a Light Duty (Type A) site, for better efficiency from each individual 
ground rod, the ground rods should be installed farther
apart than the 1.8 m (6 ft) allowed by NFPA 70-2017, Article 250.53, such as 
the sum of their respective lengths. See
Figure 4-6 for more information.
Where not part of a ground ring system, such as at a Light Duty (Type A) site, 
the entire length of the rod shall be in contact with soil (NFPA 70-2017, 
Article 250.53). It is recommended to install the ground rods so the top of the 
rod is buried to a minimum depth of 610 mm (24 in.) below the surface of the 
earth (NFPA 780-2017, section See
Figure 4-11. Standard Duty (Type B) and Extra Duty (Type B2) Sites:
* Where part of a ground ring system, the top of the ground rods shall be 
buried to the depth of the ground ring, typically 762 mm (30 in.) minimum below 
finished grade. See "External Building and Tower Ground Ring" on page 4-25.
* Where part of a ground ring system, ground rods shall be installed at 3 m to 
4.5 m (10 ft to 15 ft) intervals (ATIS-
0600334.2013, section 5.3.2).
* See "External Building and Tower Ground Ring" on page 4-25 for additional 

Should be able to find a copy of R56 on the repeaterbuilder dot com web pages.  

73, de ed -K0iL
Omaha, NE

-----Original Message-----
From: RFI <rfi-bounces+eedwards=oppd.com@contesting.com> On Behalf Of Frank 
Sent: Monday, August 10, 2020 10:57 AM
To: rfi@contesting.com
Subject: [RFI] Depth of wires between ground rods?

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When using large-gauge wire to tie together ground rods, is there an optimal 
depth to bury the wire? I have the relevant guides but am not finding that 
particular info.

Thanks and 73,

Frank K6FOD

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