NEMA Type 7 Hazardous-Area Enclosures: Challenges and Best Practices for Installation and Maintenance

National electrical manufacturers association (NEMA) Type 7 explosion-proof enclosures are widely regarded for their robust construction and dependable operation. These enclosures are sustained without the additional safety systems required to ensure the operation of a purged and pressurized piece of equipment. Similarly, NEMA Type 7 enclosures are maintained without the costly component inventory that may be required to ensure maximum uptime of nonserviceable encapsulated equipment. NEMA Type 7 enclosures are generally constructed with cast aluminum or iron-based materials and are capable of withstanding numerous explosive events. They ensure hazardous-area safety by extinguishing flames through precision-machined surfaces and controlling structural deformation should an explosive event occur. However, if maintenance practices are not designed to ensure the integrity of the enclosure, repeated access to the internal equipment and oxidation of the critical surfaces may lead to the loss of the enclosure's explosion-proof protection.