[TowerTalk] Fwd: Re: Earthing a tower

[Jim Lux]

On 12/30/12 11:28 AM, Eugene Jensen wrote:
> This keep coming up from time to time and being a retired electrician the
> NEC  has been updated in the late 90's.

yes, the big update around then was to eliminate the use of a single 
ground rod as your grounding electrode, as well as using water pipes. 
Those can be "part" of a grounding system, but not the sole means, for 
the most part.


   There is requirement for a ring
> ground and it's all laid out in code. The information is ready available
> from lots of sources and all hams with or installing a tower should follow
> code.

Bear in mind that the NEC (NFPA 70) is not the code that drives the 
grounding for lightning protection (NFPA 780), although there's plenty 
of NEC stuff that is driven by lightning protection considerations.


  Besides the house you save is yours. I helped a friend of mine with
> his electrical system after he took a super hit and if he had been in chair
> when it struck he would had been killed. On inspection I found over the
> years the tower had corroded the connection's away at it ground rods.

This is one of the big advantages of the Ufer ground: done properly, it 
should last forever with no maintenance.  The rebar or copper wire 
inside the concrete is good forever, if no water is pooling where the 
conductor comes up through the surface, that should be pretty durable, 
and the bonding of "ground system" to "grounding electrode" if done with 
approved means should last a very long time.

It
> came in on the coax's and to find it pass to ground return by the electrical
> line's.  When I installed both of my towers under permit it had to pass
> electrical inspections.  Also just a point of information either use cad
> welds or proper mechanical approved  clamps in your grounding system. 73
> Gene AA4VX
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Al
> Kozakiewicz
> Sent: Sunday, December 30, 2012 1:10 PM
> To: Patrick Greenlee; towertalk
> Subject: Re: [TowerTalk] Fwd: Re: Earthing a tower
>
> Have your friend Google "Ufer ground"
>
> Al
> AB2ZY
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> Patrick Greenlee
> Sent: Sunday, December 30, 2012 12:17 PM
> To: towertalk
> Subject: Re: [TowerTalk] Fwd: Re: Earthing a tower
>
> I have a friend who is a ham and is EE with 30+ years of antenna design
> experience.  He tells me emphatically, "concrete is not a good conductor."
> Given this, I'd be trying to not depend on concrete as part of a grounding
> system.  Rebar installed correctly in steel reinforced concrete is probably
> at least 2 inches under the surface of the concrete on any side, top, or
> bottom.  Weld plates installed when the concrete was wet (to give you
> something to anchor to) or bolts or other components set into the concrete
> are typically NOT in contact with the rebar cage inside the concrete (which
> is not a good conductor anyway.)  So again, it is better to not rely on the
> concrete to conduct.
>
> 73 Patrick AF5CK
>
> -----Original Message-----
> From: Jim Lux
> Sent: Wednesday, December 26, 2012 8:58 PM
> To: towertalk
> Subject: [TowerTalk] Fwd: Re: Earthing a tower
>
>
>
>
> -------- Original Message --------
> Subject: Re: [TowerTalk] Earthing a tower
> Date: Wed, 26 Dec 2012 17:28:43 -0800
> From: Jim Lux <jimlux at earthlink.net>
> To: Jim <zl2bmh at xtra.co.nz>
>
> On 12/26/12 3:14 PM, Jim wrote:
>> Hello.
>>
>> I hope I have sent this correctly, as it's my first post.
>>
>> Is it necessary to earth a tower?
>
>
> Yes..
>
> If your tower is securely bolted to a concrete base with bolts and there's a
> decent amount of rebar in the base, it's probably pretty well
> grounded/earthed.
>
> The concern is whether the bolts are in close contact with the concrete with
> no tiny crack for water to get in and corrode the steel, or for the water to
> create steam in the event of a lightning stroke.  Typically, this is assured
> by keeping the top of the concrete above grade and sloped so that water
> doesn't just sit on it.
>
> If it's just sitting on the bare soil, you might want to do some more
> grounding.
>
>
> A bigger issue is whether the coax shields are bonded at the bottom of the
> tower, or where they come into your house, etc.
>
>
>
>
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