In California contractors are limited to 800A Services. Larger loads must be designed by EEs.
Typical design out here would be:
External, pad mounted oil cooled POCO XFRMR
480V 3 phase service to NEMA1 Service in dedicated room close by the XFMR with two doors.
@ 3,000 Amps either 7 parallel 1000kcmil copper ( underground ) service feeders or ( above ground ) bus duct.
From the Service's integral Distirbution Board these loads at 480Y277:
Elevators 480
Firepump 480 ( with backup power ATS )
HVAC 480
1 Landlord/Site Lighting Panel 480Y277
4 to 8 Daughter Panels 225A @ 480Y277 with utility rooms each floor.
1 or more dry type XFRMRS at each 480 panelboard to provide 208Y120 (typically K-13 type with copper windings for office computers)
Common point grounding for all neutrals back at the service -- oversized grounding conductors from dry type XFMRS.
3/0 Ufer ground in footing, bonded to all necessary conductive paths via the Service 'rail'.
Connections between loads and the Distribution Board ( at the Service ) to be strictly 4/0 THHN copper -- no bus duct -- running below the slab ( PVC ) or above ( EMT -diecast )
Panels surface mounted in dedicated rooms.
Master LCC in main electrical room.
HVAC provided as a porta-pack atop the roof.
Elevators: hydraulic piston type up to four floors.
Structure to be tilt-up concrete curtain wall -- floors to be cast in place on pan decking with heavy steel post and beam on 30 foot centers. All interior trim to be 20 gauge tin or better.
TI Branch loads to be wired in 10-4 MC with occasional EMT.
No one makes a jump to vertical bus duct or medium voltages at your threshhold.
[This message has been edited by Tesla (edited 06-24-2006).]
