On 5/9/13 10:05 PM, Grant Saviers wrote:
Brazing works to steel as well as Cu, with the use of flux on the
steel. On Cu, Ag/ P (Harris Stay-Silv 15) containing brazing alloys are
self fluxing and are pretty much the standard for HVAC and refrigeration
piping. Georgia Copper sells it specifically for ground system
brazing. http://www.gacopper.com/BrazingRod.html
Cadweld probably gets the nod for few-off rods and for many joints or no
Cadweld form, brazing.
Silicon Bronze can be used for steel to Cu MIG welding.
Interesting link re corrosion of Cu underground and how to protect it.
http://www.copper.org/resources/properties/protection/underground.html
Grant KZ1W
From a NEC standpoint, brazing is allowed only in the case where you
are using piping or structural materials as the "grounding electrode
conductor" (GEC). The NEC requires that the run from the "grounding
electrode" to the service entrance neutral be "uninterrupted", and
brazing is an acceptable way to "splice" the wires, for instance.
It's not allowed for the actual connection to the "grounding electrode":
listed compression clamp or exothermic welds are all that are allowed.
Interestingly, conventional welding, brazing, etc. is allowed when
connecting a AWG4 or larger wire to structural steel in a concrete
foundation (e.g. as part of a concrete encased grounding electrode).
For antennas and RF counterpoises, radial farms, etc. you can use
whatever connection means works for your application. There's no "life
safety" aspect to it. So if you're driving 30 rods as part of your
antenna farm, brazing is fine, as long as at least a couple of the rods
have exothermic welds or listed clamps (assuming you need a ground for
code compliance).
If you're putting up an antenna next to your house with no concrete pad
(e.g. it's just sitting on the dirt, or maybe you're burying a section
in dirt as a base, then you have a bit of a grounding problem, at least
from a NEC safety standpoint. Article 800 says that antennas need to
have a conductor bonding them to the building's ground system, so you're
going to be running a wire there anyway.
WOuld that be a good lightning ground? probably not, but that's not
what NEC cares about.. what they are worried about is a power line
hitting your antenna, or more likely, your antenna hitting a power line
(a few people die every year from this.. many fewer these days since
cable TV has become popular.. not so many folks putting up a big LPDA on
a 50 foot pushup mast on their roof with funky guy wires)
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