Consulting-Specifying Engineer - February 2009 - (Page 22)

Tunneling to success In the case of Frederick Memorial Hospital’s expansion and renovation project, the capacity and code compliance of the front end normal and emergency electrical distribution was not the only challenge. Another challenge was how to get major electrical feeders from the central energy plant to almost every corner of the campus. The existing hospital already had a limited sub-basement and tunnel system that was used to distribute feeders. The natural solution was to expand this concept and employ a system of tunnels to reach (or at least get close to) each of the major renovation and expansion areas. Although there was an increased first cost for constructing these tunnels, it was comparable to the cost of trying to route multiple conduits for multiple branches of power through the crowded ceiling space of existing, occupied areas of the hospital to reach the expansion areas. Plus, the tunnels allowed for flexibility to easily add infrastructure in the future, and for access and maintenance. The Frederick Memorial Hospital tunnel system is used to distribute infrastructure across the campus and allow access for future additions and flexibility. The completed tunnel has electrical feeders on one side and mechanical piping on the other. Photo: TLC Engineering for Architecture CUP B, and the emergency electrical distribution equipment inside were designed to serve the new hospital and a new office building, and to backfeed the campus’s medium-voltage underground emergency distribution loop that provided emergency power to most of the buildings on the campus. The new CUP B also was designed in strict compliance with NFPA 110, and can expand in the future to keep up with the growing infrastructure needs of the campus, which is essential for any electrical modernization project. With the ability to house up to nine 1500-kW engine generators, the new CUPB was hurricane hardened to withstand up to a Category 5 hurricane and elevated to above the flood plain. The initial phases included two 1500-kW engine generators (and paralleling switchgear) to backfeed the campus’s underground medium voltage emergency loop. The next phase of the CUP B expansion included three additional 1500-kW engine generators, for a total of 7.5 MW, to the capacity of the campus emergency system to serve the new hospital loads. These five diesel-powered engine-generators are served by four 20,000-gallon fuel storage tanks that provide the system with approximately five days’ worth of fuel. The engine-generators located in the existing CUP A remained in place and were used to serve existing chillers and cooling equipment in CUP A, further modernizing the campus by providing cooling capacity on emergency power. In one fell swoop, this electrical modernization project dramatically improved the reliability and capacity of the campus’s emergency power systems, and the hospi- tal’s ability to remain operational during an extended normal power outage. The central energy plant expansion at Frederick Memorial Hospital included upgrades to and replacement of the normal distribution system, which originally consisted of three switchboards of varying ages and states of disrepair. During the investigation and analysis phase, engineers determined that the plant would be expanded and three new electrical services would be added: a new 4,000-amp, double-ended switchboard to serve the hospital and a new 4,000-amp switchboard to serve all of the central plant loads. The old switchboards and services were removed. Although not the cheapest first-cost solution, this option solved numerous code, capacity, reliability, and phasing (downtime) concerns. A similar analysis led to a similar solution for Frederick Memorial’s emergency power systems. The central plant would be expanded, and two new 1250-kW diesel engine generators, paralleling gear, and new bypass isolation transfer switches would replace two old generators and undersized transfer switches. Again, NFPA 99, NFPA 110, and NEC-517 code issues, capacity needs, and phasing considerations—not to mention maintainability and reliability—were the drivers over first cost. So with all due respect to brand-new hospitals on greenfield sites, give me a messy hospital renovation project that requires electrical infrastructure modernization any day. Gelfo is principal and division director with TLC Engineering for Architecture, Jacksonville, Fla. He is an electrical PE with extensive experience in the design and testing of hospital electrical and emergency power systems. He is a LEED Accredited Professional and a Certified Commissioning Agent (CxA), serving on the Board of Directors of both the American Commissioning Group (ACG) and the U.S. Green Building Council North Florida Chapter. 22 Consulting-Specifying Engineer • FEBRUARY 2009

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Consulting-Specifying Engineer - February 2009 Contents Viewpoint News M/E Roundtable Codes & Standards Electrical Modernization: A Tale of Two Hospitals Retrofitting Office Lighting Controls Case Study New Products Equipment Lifecycles Advertiser Index Green Space

Consulting-Specifying Engineer - February 2009

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