AMATEUR ANTENNA SYSTEM "LEGAL" WORRIES?
By Ron Johnson/WE7H *UBET ARC*

Recently, I had a water damage claim denied by my insurance company
for a minor mistake on my part as a home-owner.  After worrying
about this for endless nights, it has since entered my mind
(shallow as it might be at times) a "what if" scenario like this:
 
What if lightning hit one of my antennas and I did not "meet code"
and my insurance company denied any claims?  What if not only my
equipment was frizzled but my home also burnt to the ground leaving
only my chimney standing.  What if the resultant fire caused
damaged to my neighbor's property. I don't want to end-up in jail 
and my family without a dwelling because of some code or
requirement I failed to meet.  
 
What should I do?
 
I found a current copy of "the national electrical code" which is
based upon the new edition of the "NFPA 70 National Electrical
Code": the nation's most authoritative and comprehensive document
on electrical safety addressing safety from fire and electrocution
. Since 1897, the NEC has been the industry standard for electrical
safety in the United States.  
 
In offering a summary of the article 810 "amateur transmitting and
receiving stations-antenna systems", I want to emphasize that I am
not offering any legal requirements or advice...just a quotation of
the best code available to hams. 
 (It sure beats disconnecting your antenna lead-in cables and
placing them in a milk bottle to avoid lightning damage as some
people actually do.)  Most of what I quote is obvious to many, and
there are additional measures many hams take to protect their homes
and equipment, but a review won't hurt any of us!  Most of us use
coax for feeding our antennas, but the code addresses non-shielded
wire feeders also.  Many of us now use or will someday use twin
lead, ladder-line or end fed wires.  Read on...
 
Antenna wire size: (or lead-in size) 
 
less than 150 foot span-hard drawn copper 14 awg minimum, copper
clad steel 14 awg minimum.
 
greater than 150 foot span-hard drawn copper 10 awg minimum, copper
clad steel 12 awg minimum.
 
Building clearance: (antennas and lead-in)
 Firmly mounted at least 3 inches clear of building surfaces on
(continued next page)
 
 nonabsorbent supports, such as treated pins or brackets equipped
with insulators having not less than 3 inch airgap.
 
Note: where the lead-in conductors are in a metallic shield (coax)
that is permanently and effectively grounded, the requirement is
waived.  However, lead-ins shall be so located as to make
accidental contact with them difficult.
 
Building entrance:
 
Except where coax is used (and the shield is permanently and
effectively grounded), lead-in conductors for transmitting stations
shall enter buildings by one of the following:
     1.) Through rigid noncombustible, nonabsorbent tube or bushing
     2.) Through an opening providing firm, secured minimum 2 inch
clearance
     3.) Through a drilled window pane
 
Antenna discharge units:
 
Each conductor of a lead-in shall be provided with an antenna
discharge unit or other suitable means that will drain static
charges from the antenna system.
     Note: except where coax is used and is effectively and
permanently grounded or where the antenna is permanently and
effectively grounded.
 Where a discharge unit is not installed, lightning protection may
be provided by a switch that connects the lead-in to ground when
the station is not in operation.
 
Grounding conductors:
 
All grounding conductors shall be of copper, aluminum, copper-clad
steel, bronze or corrosion resistant material.  Insulation of
grounding conductors is not required, but they must be securely
fastened and should be protected from physical damage.  Grounding
conductors for an antenna mast or antenna discharge unit shall be
run in as straight a line as practicable to the grounding
electrode.
 
Grounding electrode(s):
 
The grounding conductor shall be connected to the nearest
accessible location on the building grounding electrode, the
grounded interior metal water piping system or the power service
ground.  The grounding conductor can run inside or outside the
building and shall not be smaller than no. 10 Copper or no 8
aluminum or no. 17 Copper-clad steel.
 
Note: a single grounding conductor shall be permitted for both
protective and operating purposes.  Antenna masts are required to
be grounded to the same grounding electrode used for the electrical
service used for the electrical system of the building.  (This is
necessary to assure all exposed dead metal parts are at the same
potential). In many cases, masts are (incorrectly) connected to
conveniently located vent pipes, metal gutters, and downspouts.
This could create potential (VOLTAGE) differences  between various
metal parts of the building and lead-in conductors, resulting in
possible shock and fire hazards.  Gas piping systems are not
permitted to be used as the required grounding electrode.  Where
multiple grounding electrodes are used, they must be bonded with
jumpers not smaller than no. 6 copper.
 
Interior installation-transmitting stations:
 
All conductors inside the building shall be separated at least by
4 inches from the conductors of any electric light, power, or
signaling circuit.  (Note: this requirement holds true for coax
also!)
 
Equipment grounding:
 
All metallic parts shall be effectively connected to ground,
including all external metal handles and controls accessible to
operating personnel.
 
Supports:
 
Antennas and lead-ins shall be securely supported and shall not be
attached to the electric service mast or to poles carrying open
wires of over 250 volts between conductors.  Note: antennas  or
lead in wires shall not cross over open conductors, and side
clearance of at least two feet shall be maintained  (remember to
consider swinging in the wind).
 
Whew....That's a lot to take-in, but it really is basic and it all
makes sense.  Much of this material is also outlined in the "ARRL
Handbook".  Not meaning to cause undue concern, how many of you
have reviewed the safety, legality and adequacy of your A.C. main
feeder system to and within your shack? 
 
When I was a youth and still living at home, my mom refused to
dust, touch or even get near my equipment....I can't blame her now
that I remember my maze of wires. One of my worst electrical shock
s was a result of simultaneously touching two pieces of ungrounded
equipment which turned out to be at different ground
potential-knocking me across the room, making me wonder how I got
on the floor laying against the wall!