Scott, here in Nevada the state limits us to "work within our classification."
Local towns have their own understanding on this issue. While Reno will accept an EC'c calculations to 400 amps, neighboring Sparks lets us go to 800.
It has been speculated that these levels are based upon:
-400 amps is the largest service we can have without requiring CT's for metering; and,
-800 amps is the PoCo limit for single phase services.
Which brings us to the ultimate AHJ- the PoCo. All new services, and service upgrades, ned to be reviewed, and inspected, by them. Chances are, anything the PoCo has signed off on will be approved by the locality.
Oh, and Iwire... you're right, my attitude is influenced by local conditions. 480 is pretty rare here, and the PoCo has a strong "you don't need 480" bias. Indeed, getting real three-phase can be a challenge!
To give an illustration.... the vast majority of sparkies I've met have no idea what a "delta" system is, or a "corner grounded," - though there are quite a few in the area. These guys have never noticed a service where the voltage to ground was different for different legs- all their measurements have been leg-to-leg!
In an even worse manner, maintenance folks are seriously under-trained and inexperienced. This is what you get when your town lacks any serious industry.
[This message has been edited by renosteinke (edited 07-08-2006).]
