I use Burndy Penetrox on all metal-to-metal bonded connections. Every few
years I remove the bonding clamp (bolts, screws, etc.) and check that the
metal surfaces are still clean and not corroded. The oldest bond is still
good after 12 years.
73, Keith NM5G
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jeff
Sent: Monday, October 16, 2017 12:28 PM
To: Billy Cox <aa4nu@comcast.net>; Ward Silver <hwardsil@gmail.com>
Cc: Reflector <towertalk@contesting.com>
Subject: Re: [TowerTalk] Fwd: Grounding connection to tower legs
I have finally succumb to the wisdom of the board and ordered up some
commercial Penn Union clamps which have 3/8" u-bolts and a comparatively
huge bronze clamp. They are sized for my intended wire as well. I'm not
sure but they may also provide a flat compressive fit for strap.
Unfortunately I had to break into my son's piggy bank to pay for them but
someone mentioned insurance claims and I suppose that is a pretty good point
as the towers will definitely be the tallest thing around.
I think the consensus on the antioxidant use is mixed. I wonder how well
that stuff would hold up over years of seasonal weather exposure.
Definitely would not hurt but it's fundamentally a mix of copper and grease
and it seems like the grease would be worn away by the weather over time.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: Ward Silver
Sent: Tuesday, October 17, 2017 12:56 AM
To: Billy Cox
Cc: Reflector
Subject: Re: [TowerTalk] Fwd: Grounding connection to tower legs
A quick reply - yes, the stainless steel shim clamps can be used *in some
circumstances* but my understanding from Polyphaser folks was these are not
to be used as primary grounding clamps for heavy conductors.
These are just to attach some kind of light-duty strap or wire (or
braid!) to a galvanized pipe, tube, or rod. For the main ground connection
that is intended to handle the lightning surge, you have to use the
heavy-duty clamps.
A good source of information is usually an electrician or tower installer
who knows what the local codes are and any special circumstances that
require particular hardware, coatings, etc.
73, Ward N0AX
On 10/16/2017 11:13 AM, Billy Cox wrote:
> Good Morning All, and I am reading along this with interest given past
> posts as to the what/where of properly using worm-gear type clamp
> products.
>
> Ward ... please note that some suppliers DO seem to suggest their use?
>
> http://www.polyphaser.com/products/grounding-and-bonding
>
> On the other hand, and from the daily calls/email here as to "can I do
> this or should we do that?" with various clamp products, there are
> many many design factors that really need to be properly considered
> with this topic.
>
> So given the various present unknowns here (clamp type, bandwidth,
> thickness, type of materials and so on) I can't fully agree or
> disagree with your statements as to the use of worm-gear clamps for
> such applications. But it is interesting ...
>
> Basically this topic comes down to risk management. And as one who in
> times past did things poorly and suffered the consequences in the form
> of canceled insurance, and extra work/time/investments to overcome the
> root causes ....
>
> I would suggest each person understand their specific risks, study
> appropriate sound technical information (such as Ward's book!) to
> decide what to do there.
>
> 73 de Billy, AA4NU
>
> Disclaimer if needed: Product Manager - Ideal Clamp Products.
>
> ----------------------------------------------------------------------
> --
> *From: *"Ward Silver" <hwardsil@gmail.com>
> *To: *"Reflector" <towertalk@contesting.com>
> *Sent: *Monday, October 16, 2017 7:26:02 AM
> *Subject: *Re: [TowerTalk] Fwd: Grounding connection to tower legs
>
> > Why would the hose clamp blow apart? I have used this method for
> > decades
> and have had multiple direct lightning strikes.
>
> The mechanical forces on a conductor carrying kilo-amp currents from a
> lightning strike can be extreme - many pounds per foot of conductor.
> (This is described by Ampere's Force Law.) That's why codes require
> ground conductors for lightning rods and antennas to be secured to a
> building or support structure. (This was news to me, too.)
>
> Basically, the conductor experiences a huge jerk which would destroy
> either the conductor or whatever is trying to secure it - like a hose
> clamp. So it would be more accurate to say that the hose clamp is not
> rated to withstand the force experienced by the ground conductor and
> is not blown apart by the current. It's the mechanical force.
>
> If hose clamps have been used and the tower has taken hits without
> damaging them, then the ground conductors are not for whatever reason
> carrying enough of the current pulse to generate damaging forces. Or
> maybe the configuration of the conductor was such that the force was
> weaker than it could be. i.e. - you got lucky :-)
>
> I'm no different in that I've used hose clamps over the years for
> similar applications and got away with it. No more. As long as we're
> in True Confessions mode, I've used braid from old coax (outdoors,
> even!) and soft-soldered strap and braid to ground rods. No more of that,
either.
> Live and learn, especially now that I live back in the lightning zone
> (Missouri) with towers on a high spot.
>
> So the advice is just to use the right stuff for the job. It's not
> that expensive (a lot less than your insurance deductible, that's for
> sure) and has been engineered to minimize corrosion and handle the
> mechanical requirements of the application.
>
> I also got a question about CadWeld and those are great for ground
> electrodes but I would never use them on the tower itself. It may be
> possible to safely weld a connection to a tower but I wouldn't do it
> to a tubular load-bearing leg, not to mention the dissimilar metals
> involved and all that. I wouldn't want to weaken a cross-brace either,
> especially when there are other options designed for that exact
> application. Maybe someone with broadcast tower experience could weigh
> in on that. I repeat, for us hams, just buy the right stuff and and
> do what the manufacturer says.
>
> 73, Ward N0AX
> _______________________________________________
>
>
>
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