I'm looking for input from others concerning best practices for crimping
lugs onto solid copper wire that's exposed to the outside elements. Here's
why:
A few months ago, N4CC and I lost rotational control on one of our prop
pitch rotators. Our rotators are wired with #10 AWG copper Romex. At the
rotator, high-quality T&B copper ring lugs are crimped on the ends of the
Romex. A high-compression crimper is used on all connections. Those
connections are absolutely solid.
Last week, we systematically tested the Romex at various points between our
comm shelter and the rotator. Each Romex wire between the tower base and
the rotator measured an infinite open at the base on a Fluke DMM when
shorted at the top. It seemed impossible that #10 Romex could just fail
open on its own. Our first guess was that a hunter used the tower for
target practice and severed the Romex.
After installing a new section of Romex, we removed the old section, took it
back to the shop and started looking for breaks. None found. Finally, I
measured resistance between the lug's ring and the dug the other probe into
the wire. It still measured an infinite open. That means all conductivity
was lost between the lug barrel and the #10 wire. All three lugs measure
this way. The lugs were crimped about six years ago and have been exposed
to the weather. Still, I didn't expect a well-crimped copper lug to lose
all conduction properties. The copper wire shows signs of black copper
oxide which I believe is non-conductive. And apart from creating a
weather-proof box for the rotator connections, I'm looking for a long-term
solution. Frankly, I'm not keen about installing a small enclosure at the
tower's top to protect the crimp, although it would certainly slow the rate
of oxidation. So that brings me to best practices. Some possibilities:
1. Apply copper grease into the lug barrel before the crimp occurs; or
2. Solder the lug after crimping, using 2% silver bearing solder
Comments?
Paul, W9AC
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