Comments In line....
J. Vogel wrote:
I don't intend to ruffle any feathers, nor do I direct this at any one
individual
but, the number of assumptions made and the knee-jerk reactions and
false statements being made in response to a suggestion that
magnetic mounts can be successfully used in some circumstances is both
amazing
and somewhat disappointing. I would have hoped that we could have a
more "professional" atmosphere on this list.
Sorry to disappoint you. My reaction to the statement was not an
assumption nor a "knee jerk" reaction. This subject was discussed
in-depth in the past and there have been similar responses. While the
idea may seem like a good one it is not a safe practice.
"Best practices" if it in this case is taken to mean to use a
commercially available
professionally engineered mount which has been engineered to "withstand
100 mph wind loads" (to use an arbitrary example) instead of using a
mounting
system which will withstand much more than that, albeit not a
"professionally
engineered" solution is just wrong. I would rather go with the stronger,
more stable solution rather than compromise on the integrity of the
mounting
to attain the engineer's label. Whether that is "best" or not I suppose
would
depend upon whether your goal was safety or following the "norm".
I believe the intention was to promote "safe" and "responsible" mounting
of equipment. "Professional" was never the issue.
It has been suggested in another post
Yes..Mine..
that nothing should ever be mounted
on a tower that some idiot
Why is the person an idiot?
might at some point decided to use as a tie-off
anchor point. That is a good idea in practice, but how many of us have
attached
a lightweight yagi antenna to a tower leg, assuming that nobody would ever
be foolish enough to use it to tie off to, or even use as a foothold or
handhold?
Comon'....I'm not talking about tying off to a yagi. Give me some
credit here....We are talking about mounting structures..
Are we supposed to only use yagi antennas engineered to withstand improper
use in case some idiot decides to tie off to one? What about omni
antennas consisting
of a thin metal rod, possibly encased in a small fiberglass tube?
Being ridiculous here...... No one in the steel or tower industry would
tie off to an actual antenna.
The
point is
that while safety should be a top priority, the goal of never mounting
something
on a tower that could at some point be mis-used as an anchor or support
point
is an unrealistic goal, which I would go so far as to say that those who
propose
such a goal have not been able to meet themselves, assuming that they have
actually mounted equipment on towers.
1. Not true. The number one issue when working and mounting at heights
must be safety. Again, not cost, but safety. Mounting all equipment so
it will not come down under any circumstances. Routing cabling on towers
and water tanks so that they will not produce safety issues such as
climbing obstructions and/or tripping hazards. Grounding equipment and
following NEC/EIA requirements when routing power up a tower or tank. I
do not feel that it is unrealistic to expect a mounting structure to be
"properly" mounted. Add to that an inexperienced climber and an antenna
mount with magnets that could easily "slide" across the surface of the
tank and you have an extremely unsafe condition. There are several
people on this list that were involved in Hurricaine Katrina relief. Ask
them how many cellular antennas they saw hanging from their cabling or
damaged mounts after the storm. It is my understanding that there were
not any where the structure was still standing. And where towers had
collapsed, the cell mounts were still attached to the downed towers.
2. I propose such a goal because both myself and my guys (as well as
several thousand other tower/steel workers) work on these structures
every day. It would probably be safe to say that I have more mounting
experience on water tanks than anyone else on this list. Not
bragging...just expressing my experience. And I did not get this
experience in the last year or two. It is more like 20+ years.
As far as mounting heavy stuff which might fall off and hurt someone, I
would
assume that the reaction(s) in this thread would indicate that
non-penetrating
roof mounts, chimmney mount brackets, clamping to roof vents not
specifically
engineered to withstand such use, and all other forms of mounting which
might
under some conditions fail and allow the "heavy" objects to fall would be
outlawed in your town were you given the regulatory authority to do so. Or,
perhaps because they were "designed by professionals" they would pass
muster in your book in spite of the fact that any fool looking at them could
imagine a likely scenario in which they would fail.
I am curious why you keep going back to this "designed by professionals"
statement?
Non-Pen mounts are designed to hold a certain amount of wind loading
with the proper amount of ballast. They are meant for flat roofs. Some
are designed for peaked roofs. Chimney mount brackets are predominately
a "consumer based" item but work fine for a something like a Rootena of
small panel antenna. Obviously a 2' parabolic dish is overkill (or it
should be obvious). Vent mounts are also a "consumer based" product and
is meant for small antennas. They are not meant for "heavy" objects".
I have seen numerous "professionally engineered" solutions which I would not
use in a given circumstance because of the likelihood of it failing, and
have
in several instances used a solution designed by an "amateur" (me) so that
I could rest easier at night, knowing that I have done what I could to
mitigate
the actual risk to life and property. Sometimes that means doing things in a
way that is "out of the norm", which scares some people.
How about some examples of something that would "scare" someone. We
fabricate mounts all the time. I have no problem with fabrication or
"amateur" mounts providing they are appropriate. Using 1/2" electrical
conduit to support a sector antenna is inappropriate. Fabricating a
mount out of 2" x 2" galvanized angle iron that is stud welded into the
roof of a water tank is appropriate.
That they are
scared
by that which is not "normal" without a rational basis for their fear is
disheartening. Many rules and regulations have been foisted upon us and
have limited the options available to those less suited for the job at hand
simply because of those irrational fears.
I believe the options available are limited by more of a monetary factor
and lack of experience to do the proper job than any "fear"...
I have seen mounts which were "professionally" mounted to towers using
welded studs (either welded to existing towers or in some cases to towers
being constructed) using small diameter bolts which were definitely not
something that I would trust my life to, and other mounts that were well
engineered and would likely withstand likely wind loads on the equipment
that they were supporting, yet which will probably fail in hurricane or
tornado
force winds. Are these in-appropriate? should we engineer everything to
withstand +500mph wind loads?
Being realistic and practical are what should be the "norm". 1/4 x 20
studs have a very high shear factor when stud welded. I don't disagree
that there are also other "unsafe" conditions on tanks and/or towers.
Any work that is done to cellular specifications requires a PE stamp and
the engineer specifies stud size for appropriate shear and uplift for
the mounts and equipment installed.
Should all magnets be outlawed?
Yes....
(I see
lots of magnetically mounted omni antennas on vehicles traveling at high
speed down public roadways, can you imagine that???)
But how many times do you see people "car surfing" while holding on to
that antenna??? Lets stay on topic. The mobile antenna manufacturers
do their own testing and engineering to verify magnet strength as
compared to antenna loading vs speed/wind restriction/wind force. And
if the magnet mount antenna should fall off the car while moving chances
are that it will not leave the vehicle because the transmission line
attached to the antenna will just slam it against the car several times
until the driver says "What the hell is that?" and pulls over. No one
killed or injured and minimal damage done.
I bet some of those
responding negatively to magnetic mounts even have magnets holding stuff
on their refrigerators, one of the highest use and traffic areas in the
typical
home.
Again, even my cat does not use the magnets on the door to climb on top
of the refrigerator..... :-)
I can show numerous examples of solutions designed and built by
amateurs which in the final analysis are safer and better solutions than
commercially available, professionally designed solutions to the same
problem, but the "amateur" solutions do not have the blessing of the
designed by professionals label. Does that make them inappropriate?
No..... It does not.
In
the views of some people, sadly, the answer is yes.
Again...I do not think it needs to have a "professional" label. It does
need to be properly designed and capable of withstanding the "normal"
forces that may occur while being mounting. This includes wind shear,
ice loading, lightning/ground protection, etc.
All of that being said, whenever one is considering their options for
mounting
equipment on a tower, safety should be a top priority (and I would add
should
take precedence over having a "designed by professionals" label) and one
should never mount equipment in a fashion which is likely to cause
serious injury
or death to innocent members of the community.
You cannot limit your statement to "innocent members of the community".
All who gain access to the area in question must be provided with a safe
work area. This is required by OSHA. The owner of the tank is
responsible for providing a safe workplace. This is one of the main
reasons why there are engineers who do what they do. Sure you can
produce your own mounts and they may be fine and I do not have a problem
with it. But sadly....I totally disagree with the magnet idea and feel
that it should be eliminated in its entirety.
Too many entities/WISP's/ham radio operators/yahoos/etc allow money to
dictate how things are done over proper construction practices and
safety procedures. And THAT is wrong. I feel if a person/entity can't do
something the "right" way than they are probably out of their league.
Hell...I can't configure a server or program a piece of network
equipment such as a switch or router. If I should be asked to do a
firewall for a government agency should I try and do it myself and hope
no one breaches their network or should I call someone that knows what
they are doing and have them do it?
But wait...I don't have the money to pay the "right person" what they
are asking to do the job. Well..Maybe I am "out of my league" and should
reconsider my position as I cannot adequately provide a safe and
reliable system. Or should I take the position of "I think what I did is
safe" and keep my fingers crossed???
In closing I probably could have responded differently initially. I
apologize if I offended you with my bluntness. My primary industry
(communications/cellular/tower contracting) lost two tower workers in
Kansas within the last 72 hours after falling 500+ feet. Four workers
within the past 60 days. Safety is my only issue when we get in the air.
If I can't afford the right equipment, we don't do the job. We don't cut
corners. Period.
Be safe, think safety.
--
Bob Moldashel
Lakeland Communications, Inc.
Broadband Deployment Group
1350 Lincoln Avenue
Holbrook, New York 11741 USA
800-479-9195 Toll Free US & Canada
631-585-5558 Fax
516-551-1131 Cell
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