Intrinsic safety: explosion proof circuitry

When installing electrical circuits in hazardous locations, some form of explosion protection must be used in the United States and Canada. The traditional method has been to install these systems in explosion proof enclosures and sealed conduit. Since this type of production has proven to be expensive to install and maintain, many users have turned toward intrinsic safety as a preferred explosion protection method. Here, the author describes intrinsic safety, which is an explosion protection design technique applied to electrical equipment in wiring or hazardous locations (where a flammable or combustible material is present). The technique is based upon limiting electrical and thermal energy to a level below that which is required to ignite a specific hazardous atmospheric mixture