Seen the AL stuff, but never used it. All my AHJ's / employers have required/used steel.
[history lesson] As mentioned elsewhere on the board, "Rigid Metal Conduit/RMC" AKA "rigid" or "heavy wall" has it's origins in the late 1800's use of plumbing pipe to feed gas lamps in metropolitan areas. When Edison's newfangled "electical lights" came into being, most people wanted the new lights where the old ones were mounted - it was very easy to run the wires through the pipes, and so, with some modifications (including reaming of ends - learned, I'm sure, by fires caused by faulted insulation), we arrived at the "birth" of conduit.
IMC (Intermediate Metallic Tubing) and EMT (Electrical Metallic Tubing) were later descendents of this technology, once engineers realized that the pipe didn't have to hold pressure, just provide physical protection. Of course, IMC and RMC are still used where support of conductors or extreme physical or environmental hazards exist (Service masts, factory areas subject to damage, hazardous atmospheres), but 9 out of 10 people would identify EMT as "conduit" nowdays. [/history lesson]
A little off topic, but may I reccommend a Roto-split cutter if you do a lot of Greenfield work?
(Having used both, IMHO the Seatek cutter is superior to the Greenlee... faster, lighter, and easier to use, but here are links to both http://www.seatekco.com/rs-101a.htm http://22.214.171.124/wwwroot/greenlee/details.cfm?id=4375&upc=34953
[This message has been edited by DougW (edited 06-10-2004).]