Capital One Headquarters

McLean, VA

The short circuit analysis, protection device coordination study, and arc flash analysis provides appropriate equipment ratings and settings for all adjustable overcurrent protective devices that are installed in Capital One Office Building. An Arc Flash Study was conducted to calculate the potential arc flash energy at electrical equipment in the system. When the power study was complete, labels were installed on each piece of equipment. The labels identify incident energy available, Arc Flash Hazard boundary, Arc Flash Hazard category and protective equipment required, when working on equipment that is energized.

Electric utility power is provided to Capital one HQ building through medium voltage feeders which connect the utility transformer located on south side of the building to the utility grid lines. The secondary feeders from the utility transformers supply 480/277V power to (4) 4000A switchboards (SWBD-1, SWBD-2, SWBD-3 & SWBD-4) which serve all the building loads. These switchboards serve normal power to house electric distribution panels and back of house equipment. Normal power to the office floors is distributed from the main switchboards through (4) 2500A, 480V, 3-phase, 4-wire busways which are routed through (2) vertically stacked electrical rooms on the north and south side of the floor. Each electrical room houses one double section 225A, 480/277V three phase panel for HVAC and lighting loads and one 75 kVA serving a double section 250A 208/120V three phase panel for receptacle and computer loads. The existing emergency power comes from 800kW, 277/480V, 3-phase, 4-wire generator located on south side of the property near the utility transformer yard. The existing emergency generator serves the fire pump, emergency lighting loads and optional emergency standby loads in the building through (4) automatic transfer switches (ATS-E, ATS-EM, ATS-P, ATS-FP) and electric distribution panels.