Reason for Credential: Except as provided under s. 145.06 (4), Stats., and pursuant to s. 145.06, Stats., no person may install plumbing unless the person holds a credential issued by the department as a licensed master plumber, licensed master plumber restricted, licensed journeyman plumber, licensed journeyman plumber-restricted, registered plumbing apprentice, registered plumbing learner-restricted, registered utility contractor or registered pipe layer.Requirements of Credential: A person who holds a credential as a registered plumbing apprentice may install or modify plumbing under the supervision as prescribed by the Department of Workforce Development. A person who installs or modifies plumbing as a registered plumbing apprentice may do so if he or she is indentured under ch. 106, Stats. A person who holds the credential shall carry on his or her person the credential issued by the department while performing or conducting the activity oractivities permitted under the credential.Qualifications for Credential: A person applying for plumbing apprentice registration to install plumbing shall be indentured in a plumbing apprenticeship recognized under ch. 106, Stats. Please submit a copy of the Apprentice Contract (form JETA-4224) or proof of plumbing indentureship (provided by the Bureau of Apprenticeship Standards) for the applicant. If you have questions regarding the Apprentice Contract or program, call or write to one of the Bureau of Apprenticeship Standards offices. See below link to find contact information under the appropriate license PDF.