Electrical System Specifications

The Atrium Buildings main service is 5000 amps 277/480 volt Y, and is equipped with ground fault as per code. The recent peak demand on the main service is 1228 KW out of a maximum potential of approximately 3300 KW. The existing SCE transformer serving the building is 1500 KVA.

The main distribution for the building is accomplished by a 1600 amp 277/480 volt Y vertical bus duct system in each of the two towers. This bus duct feeds 1600 amp distribution switchboards in each tower to power the main mechanical system located on the roofs of each tower. In addition to the main vertical bus way, additional power is distributed from the main service as follows: First Floor, East and West, each area is fed by a 400 amp 277/480 volt Y feeder, additional mechanical equipment is fed by a 300 amp feeder and 2-100 amp feeders, there is one additional panel on the First Floor fed by a 150 amp feeder.

The building has a 125 KW generator that feeds the AC blowers, guard station, miscellaneous rood mounted mechanical equipment and the exit and emergency lights in the stairways.

The horizontal distribution on each floor varies in capacity due to previous tenant build outs but in general there is a 200 amp 277/480 volt panel fed directly from the vertical bus duct riser for lighting and VAV system requirements. These panels have the capacity to supply approximately 8.3 watts per foot for lighting and miscellaneous mechanical needs. For domestic needs there are 120/208 volt Y transformers and panels. Due to previous build outs some floors also have shielded isolation transformers to supply clean technical power.

The electrical system is quite flexible and can be configured to meet tenant’s specific needs.