---
kind: "section"
citation: "30 C.F.R. § 27.21"
title: "30"
number: "27.21"
heading: "Methane-monitoring system."
url: "https://uscodex.org/cfr/30/27.21"
---

# §27.21. Methane-monitoring system.

- (a) A methane-monitoring system shall be so designed that any machine or equipment, which is controlled by the system, cannot be operated unless the electrical components of the methane-monitoring system are functioning normally.
- (b) A methane-monitoring system shall be rugged in construction so that its operation will not be affected by vibration or physical shock, such as normally encountered in mining operations.
- (c) Insulating materials that give off flammable or explosive gases when decomposed shall not be used within enclosures where they might be subjected to destructive electrical action.
- (d) An enclosure shall be equipped with a lock, seal, or acceptable equivalent when MSHA deems such protection necessary for safety.
- (e) A component or subassembly of a methane-monitoring system shall be constructed as a package unit or otherwise in a manner acceptable to MSHA. Such components or subassemblies shall be readily replaceable or removable without creating an ignition hazard.
- (f) The complete system shall “fail safe” in a manner acceptable to MSHA.

## Notes

### Authority

Authority: 30 U.S.C. 957, 961.

### Source

Source: 31 FR 10607, Aug. 9, 1966, unless otherwise noted.