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