In hazardous locations requiring threaded metal conduit, how many threads must be fully engaged?

In hazardous locations that require the use of threaded metal conduit, the code mandates that a minimum of five threads must be fully engaged to ensure a proper and secure connection. This requirement is critical for maintaining the integrity of electrical systems in environments where flammable gases, vapors, or combustible dust may be present.

Engaging this number of threads provides adequate mechanical strength and helps to prevent disconnection due to vibrations or thermal expansion and contraction that can occur in these settings. Furthermore, a secure connection aids in ensuring that the conduit effectively protects the wiring from external hazards, thereby contributing to the overall safety of the installation.

While fewer engaged threads might seem sufficient, they can compromise the safety and effectiveness of the conduit system, making the requirement for five threads crucial in such hazardous environments.