Who should have this credential? A person holds one of the seven classes of blasters licenses may prepare explosive charges or conduct blasting operations in Wisconsin. The variations of activities are listed here according to each category. Class 4: A person, who either holds a license as a licensed class 4 blaster or is under the direct supervision of a person who holds a license as a licensed class 4 blaster, may conduct blasting operation and activities not closer than 2500 feet to an inhabited building for quarries, open pits, road cuts, trenches, site excavations, basements, underwater demolition or underground excavations.What are the prerequisites for obtaining the credential? Pass an exam. Applicants must be 21 years old and must submit proof of 640 hours experience under the supervision of a blaster who holds the class of license the applicant wishes to take the exam for.Comm 5 is the Licenses, Registrations, and Certifications Code. Relevant sections for this credential are: Comm 5.001 through 5.12 and Comm 5.20.