Which classes of hazardous locations are discussed in Article 501?

Article 501 of the National Electrical Code (NEC) specifically addresses Class I locations, which are those where flammable gases or vapors may be present in the atmosphere in sufficient quantities to create explosive or ignitable mixtures. This includes environments such as those found in oil refineries, chemical plants, and other areas where flammable substances are used or stored.

Class I locations are further categorized into divisions based on the likelihood and duration of these hazardous conditions, with Division 1 indicating that flammable gases are present under normal operating conditions, and Division 2 indicating that flammable gases may be present only in abnormal conditions.

The focus of Article 501 is crucial since it provides guidelines on how electrical installations can safely operate in these hazardous environments, ensuring that equipment is properly rated and installed to prevent ignition sources that could lead to fires or explosions. Understanding this classification is essential for any electrical professional working in industrial or commercial settings where hazardous materials might be present.