Introduction to Area Classification

In Introduction to Area Classification , you'll learn ...

• The purpose and need for area classification
• The fire triangle - three elements required for a fire to start and sustain itself
• Class, Division and Group designations used in NEC 500
• Class, Zone and Group designations used in NEC 505

Overview

Credit: 1 PDH

Length: 11 pages

Area classification is based on the properties of the flammable substances that may be present in an area and the likelihood that the flammable substance will be present. Area classification is used to determine the type of equipment that can safely be located in an area. Since facilities in a wide variety of industries involve the use of flammable substances, it is necessary for industry to have rules to guide engineers in the design and selection of equipment necessary to safely operate the facilities.

Article 500 of the National Electrical Code® (NEC) defines area classification based on Classes, Divisions and Groups. The Class designates in broad terms the type of flammable substance that may be present in an area (i.e. flammable gas vs. combustible dust). The Division designates the likelihood of the flammable substance being present. Finally, the Group further defines the Class by designating the specific substance (or range of ignition properties) that may be present (i.e. acetylene vs. propane). Article 505 of the NEC is similar to Article 500, but it uses Zones instead of Divisions to designate the likelihood that a flammable substance may be present. Additionally, Article 505 uses different character designations (Roman numerals combined with alphabetic letters) for Groups relative to Article 500, which uses Alphabetic letters.

This course covers the basics of NEC 500 and NEC 505. The student will learn the different types of Class, Division, Zone and Group designations used by the code. This course is relevant to electrical engineers looking for a refresher course on area classification, as well engineers in other disciplines who are involved in the design, specification, selection or location of commercial or industrial equipment, including mechanical equipment, electrical equipment and controls and instrumentation.