Consulting-Specifying Engineer - September 2007 - (Page 26)

M/E Roundtable an integrated system, then that is what we specify. The majority of our designs incorporate traditional stick-built distribution systems primarily due to lower first costs, flexibility, segregation issues and AHJ acceptance. CSE: Some engineers use breakers and transfer pairs as opposed to transfer switches, when specifying mission critical work that uses multiple buses and typically saves money. However, this lends itself to confusion regarding UL listing and ANSI requirements. Do you think this keeps other engineers away from stick-built gear? FLICKINGER: Quite the contrary, it is due to the UL listing issues for a specific application that tends to promote traditional stick-built installations. The real question is what is appropriate for the application? For mission critical applications similar to data centers, we utilize multiple automatic transfer switches that are individually mounted. This allows truly independent and redundant power distribution systems utilizing segregated bussing serving a common load. Further, the UL listing is not in question and it allows for modification and flexibility as the load increases. AMANN: While almost every paralleling system employs operable breakers to connect generators to the output bus, or for a main-tie-main, very few engineers seem to use the same approach to connecting the loads to the bus. In certain emergency power systems, i.e. healthcare facilities, a listed transfer switch (UL 1008) is required by NEC for emergency loads. But for other loads, we find that by using operable breakers (in accordance with UL 489 and ANSI/IEEE 241) we can diversify loads and maintain reliability without incurring the costs and space required when using transfer switches. This approach also allows for superior fault isolation and load-shedding schemes. Tankless Water Heaters for the Most Extreme Environments Guaranteed effective to -30°F Built to handle Withstand highly industrial environments corrosive environments Rugged Industrial Strength Components, Customized to Your Extreme Environment, Freeze Protected, Explosion Proof, NEMA 4X Keltech Specialties Include: • Safety Showers (meets ANSI Z358.1) • Heating Jackets for Corrosive or Flammable Liquids • De-Ionized Water Requirements • Reverse Osmosis Applications • Large Commercial Process Heaters Toll Free 800-999-4320 www.keltech.us Input #217 at csemag.com/quickResponse http://www.keltech.us http://www.keltech.us http://csemag.com/quickResponse

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - September 2007

Contents M/E Roundtable Cover Story: Airborne Superbugs Third-Party Liability Back to School Product Spotlight Codes & Standards Professional Practices How To New Products Jobs/Cliassifieds Specifier’s Notebook Pure Power Supplement New Technologies, Same Old Transmission Problems Wireless Battery Recharging Solar Concentration Renewables Tracking System A Mighty Wind The Importance of Load Bank Testing Quality Power for Security Systems

Consulting-Specifying Engineer - September 2007

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