On 10/26/14, 9:09 AM, N3AE wrote:
The question of tying grounds together seems to come up often. I started a
thread a few weeks back with a question on tower grounding which was hijacked
into a spirited discussion on ground-to-neutral connections in outbuilding load
panels.
Guess I'll know the "official" position shortly. Just called to schedule a
final inspection for my tower project only to learn I had to pull an electrical permit
too. Previously I was told I did not need electrical. Local officials seem to make it up
as it goes along. At my QTH however, only a Master Electrician licensed in the county can
pull an electrical permit, so it seems I must now hire someone to ground my tower, deal
with bonding, coax suppressors, etc to requirements in Article 810 of the 2011 NEC. The
challenge will be finding a local licensed electrician who is familiar with these
requirements as most work around here is residential and small business/light industrial.
To jump into the current discussion, I believe I have to follow Figure 15 from
the link below. We can argue the physics like distance and voltage differential
due to propagation time, but at the end of the day it's just the inspector's
opinion that matters.
I'll provide a summary later of how it goes.
http://www.reeve.com/Documents/Articles%20Papers/AntennaSystemGroundingRequirements_Reeve.pdf
Shawn - N3AE
Reeve's writeup is very good, and his comments on the handbook chapter
(of which I am the author/editor for the most part) are well taken.
As he points out, the NEC is sort of a hodgepodge that has evolved over
the years, and modern versions are MUCH more consistent and use better
terminology than older versions (2014 is the latest edition). Be aware
that your local jurisdiction may not use the latest version (mine
doesn't). I think for the most part that compliance with the latest
version won't cause problems with an inspector looking for compliance
with an older version (and in any case, it's the inspector's word that
is final)
With respect to guidance to amateur radio licensees, either in the
handbook or online in forums such as this, there is a fine line to be
walked between "strictly according to code" and "what people are
actually likely to do".
A good example is the code requirement for "listed antenna discharge
units", of which there are none suitable for amateur HF antenna use (at
least that I've found.)
Another is that I doubt that most wire antennas meet the code
requirements of hard drawn copper or copper clad steel of the gauges
required in the code. We can hand wave a bit and say that wire antennas
made with AWG20 wire are temporary in nature, and may fall under one of
the exceptions for such things; nobody would expect a AWG 20 magnet wire
antenna to stay up for very long.
On local codes vs NEC..
Here's mine:
That certain Code designated as the “California Electrical Code,” 2013
Edition, based upon the 2011 National Electrical Code, including Annex C
and D, published by the National Fire Protection Association, at least
one (1) copy of which is on file in the Office of the Building Official
for public record and inspection, is hereby adopted by reference and
made a part of this chapter as though set forth in this chapter in full,
subject, however, to the amendments, additions and deletions set forth
in this chapter, and said Code and provisions shall be known as the
Electrical Wiring Code for the City.
and then goes on later...
...served by adding to and amending the California Electrical Code, and,
therefore, said California Electrical Code, 2013 Edition, is hereby
amended to read as follows...
Among which is this
Article 90.4. Enforcement.
(A) Used Electrical Equipment.
Unless otherwise approved by the Building Official, all electrical
equipment installed in the City of Thousand Oaks shall be new and shall
be listed by a recognized testing laboratory. Used equipment may be
installed when sufficient documentation has been received and approved
by the Building Official. The documentation shall consist of tests by a
recognized testing laboratory sufficient enough to warrant and certify
the equipment as safe for the intended use.
-> a strict reading of this means that you can't install that used
electrically actuated telescoping tower, or for that matter, perhaps
even a used ham rig.
-> This is where having a non-confrontational agreeable attitude with
the local authorities helps. Especially if you have someone looking to
stop your project who is looking for this kind of stuff. If the local
inspector (aka Building Official) signs off, it's good.
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