Pepperl+Fuchs Blog

What’s My Hazardous Area Zone?

Posted by Matt Pavlik on Fri, Jan 10, 2014

Do you need a control panel for installation in a Zone 1 or Zone 2 hazardous area? Unlike the North American Class and Division hazardous area systems, not all Zone areas are created equal.

Hazardous area Zone Classifications

Zone means something different depending on whether you are in North America, in Europe, or elsewhere in the world. Each individual country may have its own unique electrical codes that place different requirements on the equipment in the hazardous area. We generally receive requests for installation equipment in one of four main types of Zone classified hazardous areas:

  • Class I/II, Zone 1 and 2
  • ATEX Class I/II, Zone 1 and 2
  • ATEX Zone 1/21 and 2/22
  • IECEx Zone 1/21 and 2/22

Here are some questions to ask:

What is the hazard?

Gas and dust behave differently to create explosive environments.

Where will this equipment be installed?

  • The Class and Zone (AEx Class) systems are part of the North American standards
  • The ATEX system is the European standard
  • The IECEx system is the International Electric Code standard

A system that is Zone certified for North America or ATEX may not be acceptable for installation in Australia. If the system is certified for IECEx Zones, it may not be acceptable for installation in a facility in the United States. The authority having jurisdiction determines which of these is required for your installation.

There are actually two ways equipment can be certified in North America. Both come from section 505 of the National Electric Code (NEC), and each has its own marking for a certified system. NEC 505 lists the requirements for Class and Zone hazardous areas. According to NEC 505.9(C)(2), a system built and certified to the standards spelled out in NEC 505 requires a specific marking:


Class I, Zone (1 or 2), AEx Protection Designation (e, ia, px, etc.) Gas Group (IIC, IIB, IIA) Temperature Classification (T1-T6)

Interestingly, according to NEC 505.9(C)(1), a system that is built and certified for Class I, Division 1 can be installed in a Class I, Zone 1 area, and a Class I, Division 2 certified system can be installed in a Class I, Zone 2 area. In this case, the system is required to have a different marking:


Class I, Zone (1 or 2), Gas Group (IIC, IIB, IIA) Temperature Classification (T1-T6)

This means that a certified system builder could assemble components with all necessary certifications, and install them in an appropriately rated enclosure to provide a system that is certified for Class and Division as well as the equivalent Class and Zone for North American locations. If the actual “AEx” mark is not a requirement, this may be a better option. In addition, according to NEC 506.9(C), the same rules apply for Class II areas.

Questions about Intrinsic Safety? Get the Engineer's Guide

Topics: Terminology, Ask an Expert, Approvals/ Certifications

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