The BIG problem with Al wires is that it is not elastic (unlike Cu). Them you
connect aluminum, whatever holds them together has to provide the springiness.
If you use so called barrel connectors equipped only with a screw, the Al wire
will creep and the connection will loosen up over time. That's why we had a lot
of house fires in the 50th caused by bad electric connectors. A Cu wire have
some of the same tendency but does not loos all the springiness over time. You
may sometimes see electric components like light switches with a "Not for Al
wires" stamped on them. There are connectors containing a small spring that can
provide needed pressure over time intended for Al wires.
A compression fitting will make the metal surfaces to merge or weld together,
forming a secure connection that will last over a long time.
Hans - N2JFS
-----Original Message-----
From: WA2PUQ <wa2puq@frontiernet.net>
To: Hans Hammarquist <hanslg@aol.com>
Sent: Thu, Dec 30, 2010 8:48 pm
Subject: Re: [TowerTalk] Fwd: Using aluminum wire [or aluminum clad wire]
All:
There has been quite a bit of conversation regarding the use of wire nuts on
aluminum wire. While it will probably not be a problem with ham antenna uses,
I have seen wire nuts with burned insulation because the aluminum wire, even
while twisted together, had the mentioned steel spring in the nut being used as
the only connection between those wires. The spring makes a fine toaster
element and the nuts looked it.
The reason is that the aluminum oxidizes almost immediately after the
insulation is removed even if the wire is scrubbed to clean it (that's why it
lasts so long without rusting). The trick here is to use a piece of green
ScotchBrite impregnated with Alconox. The scrubber strips the oxide, the
Alconox keeps it from returning so the wires actually make a usable connection
when twisted and nutted. And no, the flooded wirenuts are not the answer if
the wire is not treated as described above.
For aluminum house wire remediation a new crimp tool and sleeve has been
introduced by the Burndy corp. which is available only to certified
electricians on a rental basis at several dollars per connection. There is
also a three cavity flooded set screw locked wiring device (Alumicon comes to
mind) at 5 bucks per connection, but you don't need the expensive crimper.
I had to learn about this as my brother in law has an AL wired house and we had
to make a few repairs there.
----- Original Message ----- From: "Hans Hammarquist" <hanslg@aol.com>
To: <towertalk@contesting.com>
Sent: Thursday, December 30, 2010 3:29 PM
Subject: [TowerTalk] Fwd: Using aluminum wire [or aluminum clad wire]
>
> It is the square, hard pin that is the secret behind the good and reliable >
> connection of wire wrapped connections. You will not even get a close >
> result if you wrap a wire around a round pin. (Been there, done that, and >
> that was tin plated Cu wire on tin plated Cu pins.) You have the same >
> mechanism with wire nuts. Inside the nut is a spiral spring made of square >
> wire. The sharp corners will press themselves into the softer metal in the >
> conductor and form a "gas tight" connection.
>
> I wonder if we can use wire nuts to make the connections to Al wires in >
> antennas. Simple and cheap. Any comments?
>
> Hans - N2JFS
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Tod - ID <tod@k0to.us>
> To: towertalk@contesting.com
> Sent: Thu, Dec 30, 2010 11:40 am
> Subject: [TowerTalk] Using aluminum wire [or aluminum clad wire]
>
>
>
>
> One does not need to solder wire to assure good conductivity between two
>
> pieces that are 'connected' together. Western Electric ran experiments in
>
> the 'middle ages' of technology that showed wrapped joints would actually
>
> have better conductivity than soldered joints. The result was that the
>
> telephone switching centers had wire wrapped connections rather than
>
> soldered connections. The technique had cost and simplicity advantages as
>
> well. Many of our initial commercial computers had wire-wrapped > backplanes.
>
> The Western Electric experiments used copper, not aluminum and the pins >
> that
>
> were wrapped with wire were square in cross section, not round.
>
>
>
>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|