ARTICLE 506. ZONE 20, 21, 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS


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ARTICLE 506. ZONE 20, 21, 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS
ARTICLE 506. ZONE 20, 21, 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS506.1. Scope.‚ÄÉThis article extends the zone classification system to traditional Art. 502 coverage locations, with Art. 503 locations tagged on. The requirements line up with Art. 502 in a logical way, except that here again the Division 1 areas are divided into a zone (Zone 20) where the combustible agent is continuous for long periods, and a zone where the threat is routine (Zone 21) but not continuous. And as in Zone 0, the only wiring permitted in Zone 20 is intrinsically safe wiring, essentially for instrumentation. Zone 22 rounds out the area classifications, and lines up with Division 2. This article is …
Citation
Frederic P. Hartwell; Joseph F. McPartland; Brian J. McPartland: McGraw-Hill's National Electrical Code 2017 Handbook, 29th Edition. ARTICLE 506. ZONE 20, 21, 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS, Chapter (McGraw-Hill Professional, 2017), AccessEngineering Export