Nope, no typo, 1200A per 3 dimmer racks... The service is not supplied by the local poco but supplied by the customer. The HV lines come into the building, get stepped down to 12.47kV on a couple of different xfmrs and then go to customer owned switchgear. Everything from there is customer owned and maintained. Just to give you an idea most buildings in this small area have their own substation and usually have 8-16 generators for emergency backup... (and employ about 10,000 employees per building)