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Introduction to Area
Classification
Rebecca Johnson, P.E.
Overview
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
Electric 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.
The student must take a multiple-choice quiz consisting of
ten questions at the end of
this course to obtain PDH credits.
Specific Knowledge or Skill Attained
This course teaches the following specific knowledge and
skills:
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The purpose and need for
area classification.
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The fire triangle - three
elements required for a fire to start and sustain itself
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Class, Division and Group
designations used in NEC 500
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Class, Zone and Group
designations used in NEC 505
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Industry examples of area
classification designations
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Equipment protection
techniques associated with area classifications
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Equipment marking for area
classification
Course
Click on the following PDF attachment and review the document
"Introduction to Electrical Area Classification" prior to taking
a quiz for credit.
"Introduction
to Electrical Area Classification" (239 KB)
Having Trouble Downloading the PDF File?
Right click on the link. Select "Save Target As..."
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To obtain PDH credits for this course, you will need to take a quiz for
credit. Click on the link below.
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