On Friday, May 27, 2011 at 7:17:01 PM UTC-5, Home Guy wrote:
I have a small commercial building with a 3-phase, 120/212 400 amp
service.

The billing meter is in a locked cabinet (for which the local utility
has a key) and out of this cabinet run 4 large cables (each about 1 or
1.25 inches in diameter) that run to...

I wonder how common this situation is -- a hidden meter? Perhaps they
would add a viewing port if this was requested?

During a test when all computers, monitors, printers and
lights are turned off (but all UPS's are still turned on) I
read a total sum of about 4 or 5 amps across all 4 power cables.

Why not also disconnect the UPS's for a few minutes?

What equipment do you have that actually needs 3-phase power?