[Code of Federal Regulations]

[Title 30, Volume 1]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 30CFR57.6406]



[Page 360-361]

 

                       TITLE 30--MINERAL RESOURCES

 

  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR

 

PART 57_SAFETY AND HEALTH STANDARDS_UNDERGROUND METAL AND NONMETAL MINES

--Table of Contents

 

                          Subpart E_Explosives

 

Sec.  57.6406  Duration of current flow.



    If any part of a blast is connected in parallel and is to be 

initiated from powerlines or lighting circuits, the time of current flow 

shall be limited to a maximum of 25 milliseconds. This can be 

accomplished by incorporating



[[Page 361]]



an arcing control device in the blasting circuit or by interrupting the 

circuit with an explosive device attached to one or both lead lines and 

initiated by a 25-millisecond delay electric detonator.