Consulting-Specifying Engineer - February 2009 - (Page 21)

and a six-story patient tower. This project posed several electrical design challenges. There was an obvious need to increase service and distribution capacity. (We could not serve 500,000 sq ft of hospital from an infrastructure sized for 100,000 sq ft of clinic.) The new patient tower was going to be located on top of the underground campus loops for utility power, emergency power, and communications. The hospital is located only three miles inland from the Atlantic coast, in hurricane-prone Florida. The solution: modernize the normal and emergency electrical distribution systems, provide protection for the electrical equipment from potential hurricane flooding, and keep the existing clinic and campus operational by locating the new normal and emergency infrastructure on the sixth floor of the new patient tower, and use it to backfeed the clinic’s electrical systems. The new services included four normal substations, four emergency substations, and eight automatic transfer switches. Locating the equipment above the flood plain in the new portion of the building would protect the electrical system from flooding, but also allow the clinic to remain operational with only minimal downtime during the equipment switchover. Many multistory hospital modernization projects are made more challenging due to the lack of life-safety and equipment branch panels, especially 120/208 V panels, convenient to the renovation areas. Electrical engineers try to save money during new construction projects by limiting the number of these panels by running these circuits to panels on other floors, which is permitted by the American Institute of Architects’ Guidelines for Design and Construction of Healthcare Facilities for life-safety branch panels, but not for equipment branch panels, or in remote areas. Looking at the lifetime costs of construction, it often is easier and better design to simply provide life-safety and equipment branch panels on every floor or in each The new Mayo Central Utility Plant includes 7.5 MW of emergency generator capacity, with the capability to expand to 13.5 MW in the future. The CUP was designed to withstand up to a Category 5 hurricane. major area of the hospital. One argument against doing this is that there are not enough loads to justify providing these panels. But there most likely are: 120/208 V life-safety loads include fire alarm panels and medical gas alarm panels (not soda machines), and equipment branch loads often include mechanical accessories, control circuits, direct digital control panels, damper and box power and controls, etc. So include a 120/208 V life-safety and equipment branch riser system in your next new hospital project, or use a large expansion project as an opportunity to modernize and upgrade the life-safety and equipment branch systems. You will be helping the hospital in the long run. At the Mayo Clinic, the new patient tower was designed with equipment and life-safety distribution (as well as normal and critical) on each floor and in each major area of the hospital. This feature simplifies future renovation projects and provides the hospital with greater flexibility to add and correctly circuit loads of any type in the future. Central energy plant: the heart of the modernization project The Mayo Clinic project was one piece, albeit a very big piece, in an overall campus master plan. The engineering infrastructure master plan was the campus’s 20-year master plan, with particular focus on the next five years of planned construction, which included the new hospital. Engineers quickly determined that the key to upgrading and modernizing the campus’s electrical infrastructure to meet the growing needs of the campus was a modernized, hurricane-hardened central utility plant (CUP). The existing CUP was not designed nor constructed to withstand hurricane force winds or flooding. The new CUP, designated as Consulting-Specifying Engineer • FEBRUARY 2009 21

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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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