[RE-wrenches] AL wire with DC

[Dana]

The problem with Al is that, IF there is ever a loose
connection, & associated arcing, that it melts not like
copper in the same situation which may arc but not melt.

I have come in on OG jobs where Al was employed and found J
boxes that were [sometimes wet] and had loose connections
and the splice was charred/melted and the AL wire was not
conducting & melted beyond use, directly at the splice. The
rubber linemen's tape was charred and there was a direct
short to the metal box which was at least grounded
correctly. I tend not to use Al based on this experience.

Thanks,  Dana Orzel

Great Solar Works, Inc
E - dana at solarwork.com
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"Responsible Technologies for Responsible People since 1988"

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf
Of R Ray Walters
Sent: Friday, July 23, 2010 7:46 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

I try to keep it in copper for DC, as I had always heard of
trouble with Aluminum on DC. (True or Old Wrenches Tale?)
We definitely go to Al on long AC runs, as its whats
available, and the cost difference becomes remarkable.
I've seen small cuts in Al, later corrode completely through
the conductor.(AC run) I'm not sure what would happen it
were DC.
Probably depend on whether it was positive or negative, and
which was bonded to ground? (either accelerate the
corrosion, or act as cathodic protection?)

R. Walters
ray at solarray.com
Solar Engineer