Wow, I am surprised at all of the bad vibes about using aluminum. Our POCOs here use 100% aluminum, all the way down to #6 for street lights.
The key in using aluminum is installing it properly. If the backfill is clean and the splices/terminations are done correctly, it works. That's just it......Getting it installed correctly.
No direct burial cable is safe from dig-ups. Most failures result from nicks (planting a bush for example). The cable gets a nick from a shovel but nobody says anything and just tapes it (if anything) and buries it. Even copper DB will fail if nicked.
I get the impression that you are looking at some long runs or you wouldn't have asked the question. You can't get aluminum any smaller than #6 anyway, but I would imagine that you'd need that size or more. You certainly can't use the standard tap connectors usually used in LV lighting. You would need to use dual-rated terminals, preferrably Hypress type that provide a copper-equivalent termination. By the time you invest in the terminals and the tooling, you might not be saving any money by using aluminum.
On a good note, aluminum wire fails much more quickly when it has been damaged than copper when direct-buried. Usually, troubleshooting to locate the fault is pretty simple. I did my time servicing an apartment complex that used 100% aluminum that had been nicked and damaged since the day it was installed. I must say that it's predictable.
[This message has been edited by EV607797 (edited 12-18-2006).]
[This message has been edited by EV607797 (edited 12-18-2006).]
