NEMA’s electroindustry May 2010 - 21

› Formation of USNC TAG for Electrical Products Used in Agriculture
NEMA members have an opportunity to join an activity that will enable participation in the development of new standards that will in turn generate requirements applicable to products used in agriculture. The U.S. National Committee(USNC)/ IEC Technical Management Committee has approved a request by the American Society of Agricultural and Biological Engineers (ASABE) to register as a participating member of IEC/SC 61H Safety of electrically-operated farm appliances and has assigned ASABE as TAG Administrator. Scott Cedarquist has been appointed as TAG secretary. Clifton Brick, Radio Systems Corp., has been appointed as the initial technical advisor. Currently, the USNC is a non-member of SC 61H and the new registration will be

recorded shortly. An effort is underway to establish a TAG of all material interests. SC 61H’s scope is to prepare international safety standards for electrical appliances primarily intended for agricultural use on farms, such as for electric fencing, harvesting, processing, protecting

packaging, breeding, or cultivating agricultural produce. Anyone interested in joining this USNC TAG should contact Scott Cedarquist at cedarq@asabe.org. ei Ken Gettman, Director of International Standards | ken_gettman@nema.org

› LVDE Publishes Selective Coordination White Paper
Recent changes to the National Electrical Code® (NEC) regarding selective coordination have changed the way engineers must design life safety and other critical power systems. The Low Voltage Distribution Equipment Section has responded to this need by publishing a White Paper on selective coordination. Its purpose is to provide guidance to system design engineers on how to comply with the requirements for selective coordination in the NEC. NEC requires selective coordination in emergency, legally required standby, and critical operations power systems. It is also required in the essential electrical system in healthcare facilities and where two or more elevators are supplied from a common feeder. This is to ensure that if an overload or fault occurs in one circuit, other circuits will not lose power. The paper includes the following: 1) description of the key functions of the overcurrent protective devices (OCPDs) used in low-voltage applications for meeting selective coordination requirements per the latest version of the NEC 2) discussion of selectivity coordination application information provided by manufacturers and implications for system design 3) importance of including both phase currents as well as ground fault currents for elective coordination 4) role of the system design engineer and the necessary interaction with applicable Authorities Having Jurisdiction 5) overview of considerations for designing selectively coordinated systems The White Paper provides detailed guidance on how to achieve coordination and describes the various factors and inputs that need to be considered by the design engineer. Application challenges such as mixing different types of OCPDs or mixing OCPDs of the same type from different manufacturers and coordination with generators and automatic transfer switches are addressed, as well as the implications for the safety of maintenance personnel caused by changes to the levels of arc flash energy. To find this and other publications, search the NEMA standards library at www.nema.org/stds. ei Ed Larsen, Industry Standards Manager, Square D by Schneider Electric | ed.larsen@us.schneider-electric.com Gerard Winstanley, Program Manager | ger_winstanley@nema.org
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NEMA’s electroindustry May 2010

Table of Contents for the Digital Edition of NEMA’s electroindustry May 2010
