Steel Conduit Joints in Hazardous Environments

Explanation:

The question is asking about the composition of threaded rigid metal conduit joints in specific environmental conditions, specifically Class 1, Division 1 locations. These locations, as defined by the National Electrical Code (NEC), are where hazardous concentrations of flammable gases or vapors are likely to occur under normal operating conditions. Given the harsh conditions, a stronger and more resilient material is needed.

Steel, option number 2, is thus the correct answer, due to its robustness and durability. To provide additional context, consider the example of a steel rod and an aluminum rod end to end. Despite the slight variation in temperature at the joints due to heat conduction, it is the robust and resilient characteristics of steel that make it suitable for conduits in hazardous environments. Aluminum, on the other hand, lacks the same level of durability or resistance to adverse conditions.

It is crucial to use the appropriate materials in Class 1, Division 1 locations to ensure the safety and proper functioning of electrical systems where the risk of flammable gases or vapors is present. By using steel for threaded rigid metal conduit joints, the integrity of the system can be maintained even in challenging conditions.