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AES Section Meeting Reports

Pacific Northwest - December 13, 2011

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Summary

The PNW Section held its December 2011 meeting at Opus 4 Studios in Bothell WA, featuring Mark Rogers speaking about the latest National Electrical Code as it relates to sound systems.

Mark Rogers is Director of the AV Department at the Greenbusch Group, a Seattle acoustical consulting firm. He is a designer of audio/visual systems, including sound reinforcement, audio reproduction, video projection and displays, videoconferencing and audioconferencing, and related control systems. Typical projects include airports, train stations, corporate boardrooms, convention centers, universities and hospitals. He has designed and installed AV for over 40 years, and also teaches classes and seminars on AV technology. He is a registered Professional Engineer (Washington and Idaho) and earned his BSEE at the University of Idaho. He is a past Vice Chair and Committee member of the PNW AES Section.

The National Electrical Code (NEC, aka NFPA 70) is a model code created and published by the National Fire Protection Agency (NFPA), and is concerned with fire and shock safety. Parts of this code apply directly to sound systems, including portable systems (such as a system used for a concert), and many important changes are in the latest revision. The NEC is adopted (and sometime modified) by local jurisdictions and is law in virtually all of North America.

The code is huge and constantly being revised. Mark breezed through some pertinent items for sound people that often amaze and confuse them, especially some of the latest requirements. For one, the code is only concerned with safety, not whether your system actually works correctly. The person who approves an installation (the AHJ or Authority Having Jurisdiction) has many obscure ways to thwart your approval, such as checking for "listed" approval of products, and even dealing with semantics of what "listed" means. After seeing the code requirements of many aspects of audio wiring and installations, it was clear that few current installations would meet the new code.

A break was held, with door prize winners:
- Rob Baum won a TWiT (Leo Laporte's This Week in Tech) keyfob
- John Hardwick won an AES Beetle Clip
- Bob Smith won an Opus 4 Studios DVD-A/BluRay of the Julian Garvue Trio
- Jayney Wallick - signed copy of the book, "Where Discovery Sparks Imagination" by the American Museum of Radio & Electricity's John Jenkins and Jonathan Winter, courtesy Bob Smith
- Mark Edman - signed copy of the book, "From Downbeat to Vinyl: Bill Putnam's Legacy to the Recording Industry" by Bob Bushnell and Jerry Ferree, courtesy Rick Chinn


After the break, Mark described some of the newly revised National Fire Alarm Code (NFPA72), which has been renamed the National Fire Alarm and Signalling Code. Parts now apply to sound systems used for emergency announcements, even with systems that are not required or used primarily for emergencies (like the system that you were hired to provide for a show). NFPA 72 is also adopted as law in most places. A method for muting any sound system in favor of alarms and/or announcements is required, as well as strict intelligibility requirements. Beware if you agree to allow your sound system to be used as part of an emergency announcement system.

A list of references for NFPA codes, equipment certifications, grounding, and intelligibility tests was provided.

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