---
kind: "section"
citation: "30 C.F.R. § 75.1320"
title: "30"
number: "75.1320"
heading: "Multiple-shot blasting."
url: "https://uscodex.org/cfr/30/75.1320"
---

# §75.1320. Multiple-shot blasting.

- (a) No more than 20 boreholes shall be fired in a round unless permitted in writing by the District Manager under [§ 75.1321](/cfr/30/75.1321.md).
- (b) Instantaneous detonators shall not be used in the same circuit with delay detonators in any underground coal mine.
- (c) In bituminous and lignite mines, only detonators with delay periods of 1,000 milliseconds or less shall be used.
- (d) When blasting in anthracite mines, each borehole in a round shall be initiated in sequence from the opener hole or holes.
- (e) Arrangement of detonator delay periods for bituminous and lignite mines shall be as follows:
  - (1) **When blasting cut coal—**
    - (i) The first shot or shots fired in a round shall be initiated in the row nearest the kerf or the row or rows nearest the shear; and
    - (ii) After the first shot or shots, the interval between the designated delay periods of successive shots shall be at least 50 milliseconds but not more than 100 milliseconds.
  - (2) **When blasting coal off the solid—**
    - (i) Each shot in the round shall be initiated in sequence from the opener hole or holes; and
    - (ii) After the first shot or shots, the interval between the designated delay periods of successive shots shall be at least 50 milliseconds but not more than 100 milliseconds.

## Notes

### Source

Source: 53 FR 46786, Nov. 18, 1988, unless otherwise noted.

### Authority

Authority: 30 U.S.C. 811, 813(h), 957.

### Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.