When a misfire is suspected, persons shall not enter the blast area-
(a) For 30 minutes if safety fuse and blasting caps are used;(b) For 15 minutes if any other type detonators are used; or(c) For 30 minutes if electronic detonators are used, or for the manufacturer-recommended time, whichever is longer.
30 C.F.R. §57.6310
61 FR 36801, July 12, 1996, as amended at 85 FR 2027 , Jan. 14, 2020 85 FR 2027 , 3/16/2020