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Intrinsic safety (IS) is a protection technique for safe operation of electrical equipment in hazardous areas by limiting the energy available for ignition. In signal and control circuits that can operate with low currents and voltages, the intrinsic safety approach simplifies circuits and reduces installation cost over other protection methods. Areas with dangerous concentrations of flammable gases or dust are found in applications such as petrochemical refineries and mines. As a discipline, it is an application of inherent safety in instrumentation. High-power circuits such as electric motors or lighting cannot use intrinsic safety methods for protection.

Certifying agencies

Several different agencies develop standards for intrinsic safety, and evaluate products for compliance with standards. Agencies may be run by governments or may be composed of members from insurance companies, manufacturers, and industries with an interest in safety standards. Certifying agencies allow manufacturers to affix a label or mark to identify that the equipment has been designed to the relevant product safety standards. Examples of such agencies in North America are the Factory Mutual Research Corporation, which certifies radios, Underwriters Laboratories (UL) that certifies mobile phones, and in Canada the Canadian Standards Association.^[1] In the EU the standard for intrinsic safety certification is the ATEX directive, while in other countries around the world the IECEx standards are followed. To facilitate world trade, standards agencies around the world engage in harmonization activity so that intrinsically safe equipment manufactured in one country eventually might be approved for use in another without redundant, expensive, testing and documentation.