LowVoltBook - Table of Contents Foreword . . . . . . . . ....

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Table of Contents i Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Unit 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Unit 2. NEC Introduction [Article 90] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Unit 3. Definitions [Article 100] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Unit 4. General Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Unit 5. Understanding Grounding Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Unit 6. Earth Grounding of Communications Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Unit 7. General Wiring Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Table of Contents
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ii Guide to Low-Voltage & Limited Energy Systems
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The National Electrical Code ® (NFPA stan- dard 70-1999) contains installation rules for all kinds of electrical products and systems. It is adopted into law by more than 42,000 states, counties, cities, and smaller jurisdictions. Many electrical professionals, including elec- tricians, contractors, and even inspectors, think of the Code primarily as a “power wiring” book. And so it is. But not just power wiring. The National Electrical Code also provides detailed requirements for the installation of many types of low-voltage wiring systems. New businesses, home offices, and many homes today are having low-voltage wiring installed to meet the need for state-of-the-art technologies for audio, video, telecorurnunica- tions, and high speed data transfer. But many electrical professionals are not familiar with the important NEC ® safety requirements for the installation of non-power installations. Too often, low-voltage systems aren’t installed properly or inspected for Code compliance and user safety. Some jurisdictions don’t even require electri- cal permits for the installation of telephone, cable TV, access control, nurse call, fiberoptic, and other low-voltage control and communica- tions circuits-even though these systems are cov- ered by the National Electrical Code . THE NEED TO INSPECT LOW-VOLTAGE SYSTEMS There are important safety reasons to inspect low-voltage installations for Code compliance. Here are just a few of them: • Audio - Audio voltages can be as high as 70 volts AC. • Telephone - Telephone ringing voltages can be as high as 90 volts AC. • Shock hazard - Incorrectly instalied low- voltage wiring may accidentally become ener- gized at line voltages, thus endangering both installers and users. • Grounding - Proper grounding of communi- cation circuits, CATV cables, TV and satellite masts, etc. are essential to prevent fires and elec- tric shock from dangerous potential differences between the electrical systems. • Working space - In general, low-voltage dis- tribution equipment must meet the same working clearances as all other equipment rated under 600 volts [Section 110-16]. • Broadband - A new Article 830 on “Net- work-Powered Broadband Communications Sys- tems” was added to the 1999 Code , covering futuristic Information Superhighway wiring sys- tems for interactive multimedia services. • Lifeline - Many jurisdictions now require that free or low-cost “lifeline” telephone service be made available to all citizens, recognizing that telephone corurnunication is not an option but a necessity in today’s world. With new types of Internet and interactive services beginning to
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LowVoltBook - Table of Contents Foreword . . . . . . . . ....

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