Electrical Equipment for Explosive Atmospheres


Ensuring that electrical equipment will not ignite an explosive atmosphere is serious business. Explosive atmospheres can be found in wide range of workplaces, including refineries, fuel storage facilities, dry cleaning plants, paint finishing areas, grain elevators, flour mills, plastic processing plants and candy factories.

These atmospheres are defined as a mixture of flammable substances with air, under atmospheric conditions, in the form of gases, vapors, or dust in which, after ignition has occurred, permits self-sustaining propagation.

The area in the workplace where an explosive atmosphere is, or could be, present is called a hazardous (classified) location and there are two primary systems used to classify these areas worldwide; the Division System (primarily in North America) and the Zone System, each further subdivided to identify the frequency of occurrence of the hazard.

Frequency of Occurrence

Division System

Zone System


Division 1

Zone 0


Zone 1

Under Abnormal Conditions

Division 2

Zone 2

Electrical equipment installed in these locations must be tested and certified against the appropriate standards to ensure it will not ignite an explosion, due to arcing or sparking contacts or elevated surface temperature.

There are a number of protection methods (standards) available to equipment manufacturers in order to obtain certification of their products for use in an explosive atmosphere. The choice of protection method (e.g. Intrinsic Safety, Explosionproof, Flameproof, etc…) depends upon its suitability for the specific classified area as well as its fit with the specific product design and application.

FM Approvals is a world leader in the testing and certification of electrical equipment for use in explosive atmospheres and can help manufacturers seeking global certification develop comprehensive testing and certification programs that address the specific requirements for their products around the world.

FM Approvals is recognized as a Nationally Recognized Test Lab (NRTL) by the Occupational Safety and Health Administration (OSHA) in the US, a Certifying Body by the Standards Council of Canada (SCC) in Canada, an ATEX Notified Body in Europe, and a Certification Body under the IECEx Scheme by the International Electrotechnical Commission (IEC).