SEE CAPS BELOW
-----Original Message-----
From: Randy
Sent: June 18, 2013 20:44
To: K0DAN
Subject: Re: [TowerTalk] Screw Anchor Experience
Wow. I wonder what the source of the corrosion/electrolysis actually was?
DISSIMILAR METALS IS THE BASIC ANSWER; THE CHEMISTRY IS MORE COMPLEX, BUT
THE FURTHER APART MATERIALS ARE ON THE ATOMIC TABLE, THE MORE THERE WILL BE
GALVANIC ACTION. SOME INSTALLATIONS RECOMMEND SACRIFICIAL ANODES, OTHERS
ELEVATED PIERS, ETC. MOST OF THESE ARE EITHER BEYOND THE BUDGET OF MOST HAM
APPLICATIONS, AND/OR ARE BEYOND THE GENERAL KNOWLEDGE & FOLKLORE OF HAM
INSTALLATIONS. ALSO, STATISTICALLY SPEAKING, MOST TOWERS DON'T COME DOWN
(DUE TO LUCK, THE HAND OF GOD, ETC.).
There are millions and millions of utility poles guyed with these
things...and methinks
that they aren't isolated from the grid, but tied into the
neutral/ground, am I right?
YOU ARE RIGHT ABOUT THERE BEING PLENTY OF UTILITY ANCHORS. I DON'T KNOW IF
THEY'RE TIED TO NEUTRALS. I WOULD SUSPECT THEY HAVE THEIR OWN SEPARATE
GROUNDS, WHICH MAY OR MAY NOT BE TIED TO NEUTRALS (MOST POWER UTILITY
SERVICE IS 3 PHASE @ 440VAC AND UP...THAT CRAFT IS BEYOND ME). I ALSO
SUSPECT THE UTILITIES INSPECT/REPAIR/REPLACE ON FAR MORE REGULAR INTERVALS
THAN HAMS. ALSO, THEY HAVE LOTS OF REDUNDANCY ON THEIR POLES...IF ONE GOES
DOWN IT IS HELD UP BY THE OTHERS AND EVENTUALLY FIXED. KIND OF APPLES &
ORANGES WHEN COMPARED TO YOUR TYPICAL HAM INSTALLATION.
I do know that, on occasion, the ground/neutral coming off the pole is
not at exactly "ground"
potential. People familiar with boats know that sacrificial zinc anodes
are often attached to boats
to prevent other metal parts from eroding due to electrolysis, since
zinc is lower down on the
electrolysis totem pole than other metals...
EXACTLY. I HAVE NO EXPERTISE HERE, BUT KNOW THE CONCEPT. IN MY EXPERIENCE,
THIS TYPE OF CRAFT IS BEYOND THE TYPICAL HAM INSTALLATION AND IS RARELY OR
NEVER SEEN IN THE DOCUMENTATION PROVIDED BY TOWER MANUFACTURERS, AND
CERTAINLY NOT PROVIDED BY HAM DEALERS WHO WANT TO MOVE MERCHANDISE AND DON'T
KNOW OR CARE ABOUT THE INSTALLATION THEREOF. ALSO, MY CRASHED TOWER WAS UP
15+ YEARS AND CAME DOWN AROUND 1998. I WISH IT WAS STILL IN PLACE, BUT AT
WHAT POINT TO TOWER MANUFACTURERS, DEALERS, AND BUYERS CONSIDER A STRUCTURE
TO BE AT END OF LIFE CYCLE? I THINK WHEN MOST HAMS INSTALL A TOWER, THEY
EXPECT IT TO BE THERE "FOREVER" (GOOD LUCK). I'M NOT BEING SNARKY...I
EXPECTED MINE TO BE THERE "FOREVER", BUT I WAS MISTAKEN. I COULD HAVE ADDED
MORE LABOR/MATERIALS TO EXTEND THE LIFE CYCLE BUT I DID NOT KNOW ANY BETTER.
I once pulled up a 1/2" copper water pipe ground "rod" used on an
aluminum tower that was
mounted on galvanized pipe in the concrete base, and it was *shiny* and
noticeably thinner
on the part that had been buried. I removed the screw anchors went I
took it down but didn't
look for or notice any missing galvanizing (which we all know is zinc).
Or maybe stray voltage from one of the rigs went up the coax shield and
down the guy wire to
cause electrolysis in your case...?
WHO KNOWS? I HAVE PULLED SO-CALLED COPPER GROUND RODS (WHICH ARE COPPER
PLATED STEEL) OUT OF THE GROUND AND THEY LOOKED NOTHING LIKE COPPER, NOT
EVEN LIKE CORRODED STEEL! NEVER MEASURED THEIR RESISTANCE BUT PROBABLY 100'S
OF OHMS! CERTAINLY NOT "GROUNDS" AS WE EXPECT THEM TO BE. DITTO ON CLAMPS
AND WIRE WHICH ARE NOT OF THE SAME MATERIAL.
Really a head-scratcher...
THE CHEMISTS AND ELECTRICIANS PROBABLY HAVE A LOT OF ANECDOTAL EVIDENCE TO
ADD.
BTW SORRY FOR THE CAPS BUT WANTED MY THREAD TO BE SEPARATE FROM YOURS.
73
Randy
KZ4RV
GL ES 73
DAN
K0DAN
On 6/18/2013 8:19 PM, K0DAN wrote:
Hi Shawn...
I had screw anchors which I think I purchased from Texas Tower. They were
probably manufactured by Rohn or some other well-known tower mfgr.
IRC they were 4” augers on 4’ 3/4” (or 1”?) rod, all galvanized. They met
the tower mfgr (TriEx) spec. They were installed (with difficulty) into
local soil here near Kansas City. Which is about 2’ of topsoil on top of
packed clay. I do not know the pH of the soil.
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