Conformity Magazine- May 2008 - (Page 29) covered by the standards applicable to the complete piece of utilization equipment.5” All construction outside the industrial control panel is not examined, nor included in the industrial control panel approval. In particular, external loads (such as motors, heaters, and so on) are not examined. External control circuits, including safety-relevant circuits such as interlocking and emergency controls, are also not examined. Finally, the standard UL 508A includes within the standard no electrical safety tests. An overall machine tool, therefore, cannot be considered approved merely by the presence of an industrial control panel approval. Such a control panel approval provides assurance that the internal construction of the control panel meets the requirements of UL 508A. However, the requirements of OSHA and the requirements of the National Electrical Code, remain unfulfilled. NFPA 79 and Machinery Approvals NFPA 79 is the applicable standard for overall machinery safety in the U.S. ANSI/NFPA 79, Electrical Standard for Industrial Machinery, is a compilation of the overall National Electrical Code (NEC) requirements for industrial machinery, in particular article 670 on industrial machinery, but also various other relevant articles throughout the NEC. NFPA 79 includes within its scope the complete machine, not just the electrical panels. The standard states: “The provisions of this standard shall apply to the electrical/electronic equipment, apparatus, or systems of industrial machines operating from a nominal voltage of 600 volts or less, and commencing at the point of connection of the supply to the electrical equipment of the machine.6” This means that when a machine is approved per NFPA 79 the machine then can be assumed to meet all the requirements of the National Electrical Code, as well as OSHA requirements for equipment used in the workplace. Therefore, only after the overall machine is approved to NFPA 79 should the AHJ for a particular jurisdiction find the equipment “acceptable for use” under the National Electrical Code. Requirements of NFPA 79 for Machinery NFPA 79 introduces numerous requirements for machinery that are not addressed in UL 508A. These requirements are critical for machinery safety and, as mentioned, are necessary elements of overall machinery safety in light of the National Electrical Code and OSHA requirements. NFPA 79 requires constructional approval of the following critical areas: mAy 2008 Conformity 29 http://www.captorcorp.com http://www.okaya.com http://www.captorcorp.com http://www.okaya.com
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