WD,
Sounds like either a Corner Grounded Delta (like the one shown in the Schematic),
or a 1 Phase 2 Wire system with one Line Grounded (As Bjarney mentioned).
Could also be an Ungrounded system with the "Normal L-G Voltage Readings" that come from using Hi Z Volt Meters.
If you have the chance to check Voltage yourself, see what readings a Wiggy gives.
Test L-L, then L-G (Eq. Gnd) on both Conductors. See what readings pop up.
About the only way to 100% verify the system type (1ph or 3ph) would be to find the Transformer bank feeding the system, or to check the main switch gear.
Chances are if there are many Luminares and a few pumps, the system will be 3 phase.
I have seen a setup on the 405 Fwy at the 605 Jct., with both a 1 phase and 3 phase delta services for highway equipment.
The Pots are pole mounted 480 Volt 2 wire Animals, and appear to be at least 100 KVA from how large they are.
Scott S.E.T.
