The insulation on Al cable rated for direct burial is thick and tough. But,
DON'T direct bury it. Carefully pull it into correctly installed PVC conduit.
Use marker tape above the conduit, just below grade.

If you're in an area that doesn't experience ground frost, MAYBE, VERY
CAREFULLY, plant the cable in a generous amount of sand. If you're in an region
with frost, ALWAYS use conduit. 
I think it is false economy to skip the conduit. The sand application is very
time consuming. 

Buried copper wire with nicked insulation may not turn to dust, but is certainly
a MAJOR bummer, particularly if it's not in conduit, AND, it's at least 3X the
cost of Al. Al, done right, no worries.

Dick Ratico
Solarwind Electric 

--- Drake wrote:
Aluminum wire got its bad name during the era when it was use in 15 
and 20 amp circuits, with #12 and #10 wire.  That stuff is a 
nightmare.  As an electrician that has cleaned up some of the messes, 
I can supply ample horror stories.

#2 and larger sizes of AL work fine.  It is important to use 
antioxidant on the connections.  Separate copper wire from aluminum 
using a listed splicing device.

Aluminum wire will turn to white powder in an underground cable where 
the insulation has been breached.  This is true for DC or AC.



  At 05:51 PM 7/26/2010, Jeff wrote:
>I have used AL wire in DC circuits for 30 years and have never had a 
>problem. If you carefully follow the protocols for working with AL 
>you should have the same experience. As pointed out the cost 
>difference can be staggering. I'm designing an o-t-g 3kW PV system 
>now that has this array 1300' from the batteries, AL is the only 
>reasonable answer.
>
>
> From the Solar, Wind and Hydro powered office of Jeff 
> Oldham/Regenerative SOLutions
--- end of quote ---

