What is the maximum distance mines may be developed underground before requiring a mechanically operated fan?

The correct answer is based on the regulations governing underground mining operations, which aim to ensure the safety and health of miners through proper ventilation. The law stipulates that there is a maximum allowable distance that a mine can be developed underground before the use of a mechanically operated fan becomes necessary to ensure adequate airflow and ventilation.

In this context, a distance of 200 feet is significant because it reflects the balance between maintaining air quality and managing the logistics of ventilation systems. Beyond this distance, relying solely on natural ventilation may not sufficiently dilute harmful gases or provide enough oxygen for miners, increasing the risk of hazardous conditions in the mine.

Understanding ventilation requirements is crucial for foremen and mine operators, as inadequate ventilation can lead to serious safety issues, including the build-up of toxic gases or oxygen deficiency. Therefore, the regulatory threshold of 200 feet before requiring a mechanically operated fan emphasizes the commitment to miner safety and compliance with mining regulations.