Oklahoma Electrical Practice Exam

When threaded fittings are used in a Class 1, Division 1 area, a minimum of how many threads must be engaged?

1. 3 threads

2. 4 threads

3. 5 threads

4. 6 threads

The correct answer is: 5 threads

The requirement for a minimum number of engaged threads in threaded fittings within a Class 1, Division 1 area is primarily for ensuring safety and integrity in environments where flammable gases or vapors may be present. Engaging a sufficient number of threads helps to provide a reliable and durable connection that minimizes the risk of leaks, which is crucial in potentially explosive atmospheres. Engaging at least five threads ensures that the connection can withstand mechanical forces and vibrations that may occur in operational conditions, as well as thermal expansion or contraction. This level of engagement also aids in maintaining a proper seal, thereby reducing the likelihood of any hazardous gases escaping. In hazardous locations, it is essential to follow established safety standards to protect both personnel and property, making adherence to the recommended number of engaged threads a critical practice in electrical installations.