Part 23 - TELEPHONES AND SIGNALING DEVICES
- Section 23.1 - Purpose
- Section 23.2 - Definitions
- Section 23.3 - Application procedures and requirements
- Section 23.4 - Reserved
- Section 23.5 - Conditions governing investigations
- Section 23.6 - General requirements for approval
- Section 23.7 - Specific requirements for approval
- Section 23.8 - Inspection and tests
- Section 23.9 - Special requirements for complete devices
- Section 23.10 - Material required for MSHA records
- Section 23.11 - How approvals are granted
- Section 23.12 - Wording, purpose, and use of approval plate
- Section 23.13 - Withdrawal of approval
- Section 23.14 - Instructions for handling future changes in design