---
kind: "section"
citation: "30 C.F.R. § 7.69"
title: "30"
number: "7.69"
heading: "Approval marking."
url: "https://uscodex.org/cfr/30/7.69"
---

# §7.69. Approval marking.


Each approved blasting unit shall be identified as permissible by a legible and permanent marking securely attached, stamped, or molded to the outside of the unit. This marking shall include the following:

- (a) **The assigned MSHA approval number.**
- (b) **The maximum blasting circuit resistance.**
- (c) A warning that the unit's components must not be disassembled or removed.
- (d) **The replacement battery types if the unit has replaceable batteries.**
- (e) A warning placed next to the charging connector that the battery only be charged in a fresh air location if rechargeable batteries are used.
- (f) **A warning that the unit is compatible only with detonators that will—**
  - (1) Fire when an average of 1.5 amperes is applied for 5 milliseconds;
  - (2) Not misfire when up to an average 100 amperes is applied for 10 milliseconds; and
  - (3) **Not fire when a current of 250 milliamperes or less is applied.**

## Notes

### Source

Source: 54 FR 48210, Nov. 21, 1989, unless otherwise noted.

### Authority

Authority: 30 U.S.C. 957.

### Source

Source: 53 FR 23500, June 22, 1988, unless otherwise noted.