[sdiy] Grounding of inputs/outputs for modules

[KA4HJH]

On Aug 3, 2012, at 8:19 PM, Chris Muir wrote:

> 
> On Aug 3, 2012, at 5:03 PM, David G Dixon wrote:
>> In any case, much house wiring used to be made of aluminum.  Our first house
>> in BC, built in 1951, had all aluminum wiring.  It was upgraded because the
>> aluminum was considered a fire hazard (it probably wasn't), but this worked
>> well for 30+ years in those houses.  It neither corroded nor lost
>> conductivity.
> 
> 
> What a geeky electrician told me is that the problem is one is dissimilar metals. The aluminum to copper junction oxidizes over time, and the resistance goes up, causing more heat to be generated at that junction.


That plus the difference in thermal coefficients. See this article:

http://en.wikipedia.org/wiki/Aluminum_wiring

I remember when this became a big scandal in the US. I suspect that some of it could be blamed on improper installation. Used *properly* aluminum should work just fine.


On a related note, the house next door to us was vacant for over a year. When the bank finally put it up for sale they discovered that someone has ripped out all the copper. Fifty feet away and we never heard a sound.

Terry Bowman, KA4HJH
"The Mac Doctor"