They appear to assume that the guy wires on a guyed structure will be
electrically connected to the tower, so that ground rods at the guy anchors
will provide additional grounding, else why 6 ground rods for self-supporting
towers? I would have thought that many/most guyed towers would have insulated
guys.
73, Pete N4ZR
At 01:08 PM 1/4/2007, donovanf@starpower.net wrote:
>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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