[RFI] Depth of wires between ground rods?

[EDWARDS, EDDIE J]

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 4.5.1.4.1 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 4.13.2.3.1). See
Figure 4-11.
4.5.1.4.2 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 information.

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 at contesting.com> On Behalf Of Frank O'Donnell
Sent: Monday, August 10, 2020 10:57 AM
To: rfi at 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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