Conn. Agencies Regs. § 25-129-10
The requirements for registration as a limited direct exchange geothermal driller W-10 shall be one (1) year as a direct exchange geothermal driller trainee or possessing equivalent experience and training. Registration as a limited direct exchange geothermal driller W-10 permits the registrant to construct a geothermal bore hole or geothermal system up to and including the manifold connection, but limited to those bore holes employing direct exchange or direct expansion technology, as described in section 25-128-36(c) of the Regulations of Connecticut State Agencies, and associated components of a direct exchange geothermal system, including, but not limited to, drilling associated with the installation of copper or other piping containing a direct exchange heat transfer medium, the installation, repair and maintenance of piping, casing, heat transfer media, only while the registrant is in the direct and regular employment of a contractor registered for such work. The applicant shall demonstrate knowledge of direct exchange geothermal bore hole drilling by passing a written examination conducted pursuant to sections 21a-7(a)(1) and 21a-8(a)(5) of the Connecticut General Statutes.
Conn. Agencies Regs. § 25-129-10