A & AA Buildings Switchgear Replacement

Baltimore, MD

As prime consultant, BKM provided MEP design services for the replacement of the service entrance, 3,000 Amp, 208/120V, single-ended unit substation switchgear in Building A. It also included the replacements of two service entrance switchgears in Building AA. One was a 2,000 Amp, 480/277V, single-ended unit substation switchgear and the other was a 3,000 Amp, 208/120V, double-ended unit substation switchgear.

The design effort required thorough field survey of existing conditions and detailed phasing plans since the switchgear was to be replaced in its current location while the building remained occupied with all areas up and running. Also, completion of a power system study (short circuit, overcurrent devise coordination, and arc-flash analysis) was included to determine the impact of connecting the new service entrance unit substation switchgear to the existing building distribution system.

The project required intense field survey of existing switchgear rooms and of existing building infrastructure in order to develop the phasing plans and the power system study. Detailed phasing plans were required due to the need to replace the existing switchgear in the same location. Building outages had to be minimized in order to maintain building function (hospital). A power system study was required to determine the impact of connecting the new unit substation switchgear to the existing building power distribution equipment. Each building was surveyed  to obtain existing equipment nameplate data and feeder sizes and length. The field data was used to model the building’s power distribution system using SKM software. Short circuit protective device coordination and arc-flash analysis was completed. Additionally, arc-flash labels were provided to the owner.