Effective January 1, 1006; tower grounding standards in the United States are
specified in ANSI/TIA-222-G-2005.
Section 10.4 states:
Connections between a structure and grounding electroes or connection between
electrodes shall be compatible with the electrodes and be accomplished by leads
no smaller in surface area than 2/0 solid.
Gounding electrodes shall be as a minimum, be equivalent to 5/8 inch diameter,
10 feet long metal rods constructed of copper, copper clad steel, galvanized
steel or stainless steel alloy. The minimum embedment depth of grounding
electrodes shall be 10 feet. All electrodes must be connected to the
structure, however, all electrodes need not be interconnected
Section A.10.0 Protective Grounding states:
It is intended that the owner or the owner's representative will verify that
total resistance will not exceed 10 ohms based on actual on site soil
conditions. Additional grounding electrodes may be required.
For guyed masts the default grounding configuration shall be a minimum of three
grounding electrodes installed symetrically around the base of the structure at
a minimum 20 ft spacing and each symetrically connected to the base of the
structure. A minimum of one grounding electrode shall be installed and
connected at each (guy) anchor.
For self supporting structures, the default grounding configuration shall be a
minimum of six grounding electrodes installed symetrically around the base of
the structure at a minimum of 20 feet spacing. A mimumum of one lead shall be
connected to each leg for latticed structures and a minimum of thee leads shall
be symetrically connected to the base of pole structures.
73!
Frank
W3LPL
---- Original message ----
>Date: Thu, 4 Jan 2007 12:11:44 -0500
>From: <ersmar@comcast.net>
>Subject: Re: [TowerTalk] Antenna/Tower Grounding (Lightning Protection)
>To: "Richard W. Solomon" <w1ksz@earthlink.net>, <towertalk@contesting.com>,
>"Jim Lux" <jimlux@earthlink.net>
>
>Jim:
>
>----- Original Message -----
>From: "Jim Lux" <jimlux@earthlink.net>
>To: <ersmar@comcast.net>; "Richard W. Solomon" <w1ksz@earthlink.net>;
><towertalk@contesting.com>
>Sent: Thursday, January 04, 2007 10:10 AM
>Subject: Re: [TowerTalk] Antenna/Tower Grounding (Lightning Protection)
>
>
>
>>>2. Your tower ought to have at least one ground wire, minimum of #8
>>>gauge wire, to one ground rod within two feet of each tower leg. The
>>>latest version of the National Electrical Code mandates two ground rods
>>>and two wires at each leg.
>>
>>
>> Really? Which code? The 2005 NEC is silent on towers, per se. Art 810.15
>> says masts and metal structures shall be grounded in accordance with
>> 810.21. 810.21 just has the stuff about the size of the wire, straight
>> line runs, protection of the connections, and what can serve as a
>> grounding electrode.
>>
>> Art 820 (CATV etc) has very similar provisions.
>>
>>
>> Maybe you're thinking of some lightning protection code? Or a
>> recommendation of a manufacturer?
>>
>>
>> Jim, W6RMK
>>
>>
>
> I'm pretty sure I read about these new grounding requirements in the
>latest (2008) proposed NEC here on TowerTalk within the past six months or
>so. I can't just yet find that reference in the archives. I'll do more
>searching and report back to the reflector. But I'm just as certain what I
>read was not something from a manufacturer.
>
>73 de
>Gene Smar AD3F
>
>
>
>
>
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