What are the detector requirements for a continuous miner or road header regarding location, alarm level, and trip level?

• A. Must be fitted with at least 1 automatic methane detector near the cutters; alarm at 1%; trips electricity supply to the machine at 2%.
• B. Detectors are optional and alarms are not required.
• C. Detectors must be placed only at the tailgate and must trigger alarms at 5%.
• D. Detectors must monitor oxygen levels and trigger alarms at 0.5%.

Answer: (A)

Detecting methane where the electricity and ignition risk are highest is the key idea. For a continuous miner or road header, you must have an automatic methane detector placed near the cutters so any methane released during cutting is identified as quickly as possible. The alarm level is set at 1% to give workers a timely warning before gas concentrations become dangerous. If methane climbs to 2%, the system trips the machine by cutting its electrical supply, stopping operation to prevent an ignition source in a hazardous atmosphere. This combination—detector placement at the cutting zone, an early warning at 1%, and an automatic shutdown at 2%—provides both rapid notice and rapid mitigation in a high-risk area. Detectors are not optional, they’re not limited to the tailgate, and the requirement is for methane detection (not oxygen) with the specified thresholds, so alternatives that omit any of these elements don’t meet the safety standard.