Tennessee to Delaware: master plumber license reciprocity

Delaware issues a person-held Master Plumber license through the Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners in the Division of Professional Regulation. 24 Del. C. § 1807 requires that license (or a statutory exemption) to provide plumbing services or to use the titles licensed plumber / master plumber. Employees, apprentices and journeymen work under a master's supervision without their own Board license. A new master needs a journeyman's certificate from a federally-standard apprenticeship plus two years under a master plumber (or similar-level licensee in another state), or seven years under such supervision plus the Delaware vocational-technical apprenticeship equivalency tests, then Board approval and the ProV-administered master plumber exam; the application fee is $173. Out-of-state masters apply by reciprocity under 24 Del. C. § 1810 without a Delaware exam: the Board shall grant the license if the origin state's standards are substantially similar, and otherwise requires at least seven years of practice after licensure. 24 DE Admin. Code 1800 § 2.3 requires every reciprocity applicant to submit the origin state's licensure laws and regulations so the Board can make that comparison. Licenses renew biennially; from the 2026 renewal, plumbing licensees complete 5 hours of continuing education (3 code, 1 safety, 1 cross-connections/backflow) by October 31 of even-numbered years.

Tennessee does not issue a master plumber license. The state-level plumbing credentials are (1) the Limited Licensed Plumber (LLP), a personal license for work under $25,000 where the Division of Fire Prevention inspects, which the Board does not treat as a master equivalent and for which it has no exam-waiver agreements, and (2) a contractor license with the CMC-A (plumbing) or CMC (full mechanical: plumbing and HVAC) classification, issued to a business that names a qualifying agent and required for plumbing projects of $25,000 or more. CMC-A and CMC candidates need Board pre-approval ($50) before the plumbing or full-mechanical trade exam; every contractor also takes the Tennessee Business and Law exam (Prov from 2026-07-01; scores typically valid two years). Initial contractor application fee $250. The Board's trade-exam-waiver form lets a contractor whose origin board verifies a comparable plumbing or mechanical exam skip the Tennessee trade exam but not Business and Law, and it cannot be used for the LLP: Ohio plumbing maps to CMC-A, South Carolina plumbing to CMC-A, and Louisiana, Mississippi and West Virginia mechanical licenses to CMC. That waiver is contractor-to-contractor only (Ohio's OCILB listing of Tennessee as a plumbing-contractor partner is the same relationship from Ohio's side). Master plumber licenses proper exist only locally; Nashville's MPE Board issues a master plumber certificate. An out-of-state master plumber has no statewide personal recognition: to contract for $25,000 or more they need the CMC-A or CMC contractor license; to pull small-job permits they need the LLP where it is accepted, or the local master card where it is not.