RE: [TCML] primary tubing - now Aluminum wiring failures

["Dave Halliday" <dh@xxxxxxxxxxxxxx>]

Also, the anti-oxidizing paste would dry out and allow air in after a few
years.

A lot of house wiring panels are mounted in an outside wall and therefore
subject to the temperature swings from summer to winter. Al is cheaper than
Cu (and the price difference was a lot greater 20 years ago).

You can get away with this in an industrial application where the junctions
are constructed better and monitored on a regular basis. Set and forget
household wiring? No...

Dave



> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx 
> [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Quarkster
> Sent: Wednesday, November 11, 2009 12:27 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] primary tubing - now Aluminum wiring failures
> 
> Jim -
> 
> The terminations of the aluminum wire become oxidized, develop some 
> resistance across the termination, and eventually overheat.
> 
> There are several contributing factors:
> 1. Aluminum exposed to air immediately develops a 
> high-resistance oxide 
> film;
> 2. Aluminum wire is quite soft and "cold-flows" under pressure;
> 3. Aluminum's high rate of thermal expansion can cause a 
> "self-degenerating" 
> thermal-cycling problem where a small amount of resistance 
> creates localized 
> heating, which causes the wire (and any clamped connections) 
> to expand. When 
> the electrical load on that circuit is removed, everything 
> cools off, and if 
> the aluminum has cold-flowed, there is now less clamping 
> pressure, which 
> allows further oxidation in the connection, which creates 
> more resistance, 
> which gets hotter the next time the circuit is loaded, etc, etc.
> 
> I've personally seen wire-nuts on aluminum wiring that got so 
> hot that the 
> plastic wire-nut body completely melted away, leaving only 
> the conical steel 
> spring from inside the wire-nut holding the wires together.
> 
> Aluminum house wiring was a cost-saving measure that was 
> implemented without 
> adequate testing, and turned out to be a complete disaster, a 
> great example 
> of shoddy Engineering.
> 
> Regards,
> Herr Zapp
> 
> 
> ----- Original Message ----- 
> From: "Jim Mora" <wavetuner@xxxxxxxxx>
> To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
> Sent: Wednesday, November 11, 2009 11:19 AM
> Subject: RE: [TCML] primary tubing - now Aluminum wiring failures
> 
> 
> Hi,
> 
>  This is certainly not my bailey wick; but, what are the 
> failures? Is it 
> metal to dissimilar metal connections?
> (snip) 
> 
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