[TowerTalk] Fwd: Grounding connection to tower legs

[Patrick Greenlee]

Each of the three galvanized legs of my new tower bolts to galvanized 
steel coming up out of the concrete base. There are multiple bolts per 
leg.  I intend to add stainless steel tabs (like a washer) to one of the 
bolts at each of the three legs. The "washer-like" tab will extend out 
into space sufficiently to be drilled with a pair of holes to  accept 
bolts which will be used to secure copper strap in a clamping 
arrangement to maximize contact area.  Short of using zinc strap (never 
actually considered), I haven't thought of a better way to control 
dissimilar metal corrosion.  My experience in marine electronics has 
included this sort of arrangement to good advantage and effect.

The galvanized tower will only contact stainless steel and the copper 
strap (you could use wire if preferred) only contacts the stainless 
steel.  ...and now comes the part where experienced folks have 
differed.  Some use water proof coatings over all areas of contact of 
dissimilar metals and some don't.  Most of these applications were 
seagoing and subject to salt encrustation. Fresh water rinse on the 
unprotected connections  was advised to the operators but as you can 
imagine that didn't happen in all instances.  Personally, I lean toward 
coating the connections.

Yes, this is anecdotal evidence and was not published in a peer reviewed 
journal specific to the area of interest. There is no warranty expressed 
or implied as to the the fitness of purpose of any of the above which is 
offered solely for entertainment purposes to adults except were void due 
to local laws. ;) ;) YMMV

Patrick        NJ5G



On 10/16/2017 6:44 AM, john at kk9a.com wrote:
> I am not aware of any clamp for attaching copper strap to a tower leg
> other than a hose clamp and shim. Polyphaser sells a modified hose clamp
> just for this purpose. Why would the hose clamp blow apart? I have used
> this method for decades and have had multiple direct lightning strikes.
>
> John KK9A
>
>
>
> To:	Reflector <towertalk at contesting.com>
> Subject:	Re: [TowerTalk] Fwd: Grounding connection to tower legs (Kevin
> Stover, AC0H)
> From:	Ward Silver <hwardsil at gmail.com>
> Date:	Sun, 15 Oct 2017 21:35:32 -0500
>
> Use a proper clamp designed to connect copper wire to galvanized tower
> legs.  For Rohn 25, the clamp is part number R/CPC-1.25 and I'm sure there
> is a larger one for Rohn 55.  A local electrical supply house will also
> have clamps for connecting copper to galvanized pipe.  Ask for it and
> follow the installation instructions regarding how to prep the surfaces
> and any other cautions.  If you can't get the special clamp, you can also
> use bronze grounding clamps over the stainless steel shim.  Do *not* use
> stainless steel hose clamps - they will blow apart under the stress of a
> lightning strike.  You spent a bazillion dollars on the tower, protect it
> with the right non-corroding materials that are rated for the job.
>
> 73, Ward N0AX
>
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