Consulting-Specifying Engineer - February 2008 - (Page 48)

Equipment Lifecycles resistant electric switches and relays. Enclosures are developed in various materials, many of which effectively resist corrosion and protect equipment in harsh applications. Enclosures are available with keylocking and padlocking systems to deliver additional equipment security. Electrical equipment must be protected while remaining accessible. Anticipating the frequency of maintenance will help determine which additional enclosure features your application requires. Removable panels, double-hinged doors, and data interface ports assist in streamlining equipment maintenance. Additionally, enclosures are available in horizontal, low-profile, wall-mount, and several additional models to integrate seamlessly into a variety of floor plans while providing operators with improved ergonomics and equipment accessibility. Periodic enclosure inspection ensures proper performance in the environment and protection against electric shock. Where applicable, check the gasket for compression set, the latching to make certain the door seals properly, and the door interlock to ensure the accessibility meets the requirements. Also check the enclosure for corrosion and make sure all the conductive parts are properly bonded. Replacement parts and accessories, such as touch-up paint, are available from most enclosure manufacturers to enhance product life. Common enclosure requirements are found in the National Fire Protection Association (NFPA 70, also known as National Electric Code, NFPA 79) National Electrical Manufacturers Assn. (NEMA 250), Underwriters Laboratories (UL 50, UL 508A), Canadian Standards Assn. (CSA 22.2), and International Electrotechnical Commission (IEC 60529). North American practice is to match the environmental protection requirement to a specific enclosure Type rating. The most common Type ratings are: • Type 1: Enclosures are intended for indoor use, primarily to provide a degree of protection against contact with the enclosed equipment or locations where unusual service conditions don’t exist. • Type 3R: Enclosures are intended for outdoor use, primarily to provide a degree of protection against falling rain and sleet; they are undamaged by the formation of ice on the enclosure. • Type 4: Enclosures are intended for indoor or outdoor use, primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water; they are undamaged by the formation of ice on the enclosure. • Type 4X: Enclosures are intended for indoor or outdoor use, primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and hose-directed water; they are undamaged by the formation of ice on the enclosure. • Type 12: Enclosures are intended for indoor use, primarily to provide a degree of protection against dust, falling dirt, and dripping non-corrosive liquids. Third party listing from UL/CSA ensures that the selected type rated enclosure is performance tested for ingress, bonding, and corrosion, and that it meets additional construction requirements for minimum metal thickness, latching, and coating finishing. The size and mounting requirements of the application’s electronics also are critical to determining a proper fit. Engineers should calculate the minimum height, width, and depth that the equipment requires, including wire bend space, and note any space and installation limitations in the application area. Glen Kampa is program manager with Hoffman, Anoka, Minn. 80% less water. 100% better for business. Hybrid technology is for more than just cars. Jaeggi hybrid dry cooling towers use up to 80% less water than traditional evaporative towers. Since fresh water is more valuable than ever before, we designed our coolers for maximum water and electrical cost savings. In fact, installation of a Jaeggi Hybridcooler contributes to achieving LEED building certification. Contact us today for more information about environmentally efficient Jaeggi hybrid dry cooling towers. Jaeggi. Changing the language of industrial cooling. Photo by Dirk Beyer 760 541-9308 www.jaeggi.us Input #220 at csemag.com/quickResponse 48 Consulting-Specifying Engineer • FEBRUARY 2008 http://www.jaeggi.us http://www.jaeggi.us http://csemag.com/quickResponse

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Consulting-Specifying Engineer - February 2008 Contents Viewpoint News M/E Roundtable How To Write Control Sequences Mentoring Engineers: Myths, Motivations, and Models Keep Young Electrical Engineers Grounded Protecting a Vulnerable Population Codes & Standards Case Study New Products Equipment Lifecycles Advertisers Index Green Space

Consulting-Specifying Engineer - February 2008

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