Consulting-Specifying Engineer - November 2007 - (Page S11)

on-peakperformance NEC 708: Practical Impact on Backup Power Systems Disaster preparedness has entered the public consciousness; one result is National Electrical Code Article 708, which defines critical operations power systems. By Michael Kirchner Sales Training Manager Generac Power Systems Waukesha, Wis. >> E vents of the last few years have caused us to question the reliability of our critical backup power systems and consider their vulnerability to natural and human threats. Images of these events have pierced our psyche and fueled our fears—and called us to action. One of those actions was modifying the National Electric Code (NEC) with the new Article 708 that defines critical operations power systems (COPS). Article 708 was added to the NEC based on needs expressed by the federal government for standards that could strengthen homeland security. Article 708 was directed by the NEC’s Technical Correlating Committee Task Group on Emergency and Standby Power Systems for Homeland Security and created by Code-Making Panel 20. Historically, the NEC primarily has been focused on the installation of electrical equipment with an emphasis on fire safety. Article 708 significantly extends that scope to include operations, monitoring, control, and maintenance of the on-site power system for designated critical operation areas (DCOA). documentation, to mandate COPS compliance as deemed appropriate. COPS will generally be applied at vital infrastructure facilities with an impact on national security, the economy, and public health and safety. A significant element in developing a COPS is risk assessments (NEC 708.4): “In critical operations power systems, risk assessment shall be performed to identify hazards, the likelihood of their occurrence, and the vulnerability of the electrical system to those hazards.” These hazards are to include natural and human-caused events. Once the risk evaluation has been performed, Article 708 requires an action plan to mitigate hazards that are not already mitigated by the minimum requirements of the code. >> Article 708 functionally creates a new load category, COPS, to the existing list of emergency systems, legally required standby and optional standby. This, however, is the point where the discussion becomes interesting. What are real risks and what is merely hype? What are the most common failure modes of backup power systems? Though Article 708 was conceived in a post 9/11 environment, filled with fear about terrorist attacks, how do intentional human-caused failures statistically compare with other potential failure modes for on-site backup generators? Those more typical risks would include generator failure, bad diesel fuel, running out of fuel, human error, and inadequate cooling. There also are the risks of fire, wind, and flooding. Separating and prioritizing november2007 Shifting concerns With its traditional focus on fire safety, the NEC’s existing emergency system requirements (Article 700) are primarily concerned with evacuation. But Article 708 is different; it addresses the issue of whether to maintain operations throughout a disastrous event—or whether to defend in place. Article 708 functionally creates a new load category, COPS, to the existing list of emergency systems, legally required standby and optional standby. This will allow municipal, state, and federal agencies, as well facility engineering 11

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

Consulting-Specifying Engineer Contents Editor's Viewpoint Letters In The News M/E Roundtable Emergency Power for Healthcare 2007 Products of the Year Industrial-strength Lighting Hazardous HVAC Codes and Standards Management Report Jobs/Classifieds Specifier's Notebook On-Peak Performance Contents Best Battery Selector in Engine Starting Applications NEC 708: Practical Impact on Backup Power Systems Protecting Power: Specifying Outdoor Generator Enclosures Investing in Backup Power Systems Coes, Consultants, Manufacturers, and Standby Power Systems

Consulting-Specifying Engineer - November 2007

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