Conn. Agencies Regs. § 25-129-9
Registration as a limited direct exchange geothermal contractor W-9 permits the registrant to construct a geothermal bore hole or geothermal system up to and including the manifold connection, but limited to those geothermal bore holes employing direct exchange or direct expansion technology, as defined in section 25-128-36(c) of the Regulations of Connecticut State Agencies, 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, and heat transfer media. Before any registration is issued to any individual the Board shall require that the applicant submit documentation that the applicant has been actively engaged in the geothermal bore hole drilling trade as a direct exchange driller for a period of twenty-four (24) months prior to the date of application or has held a valid W-10 registration for at least two (2) years. The applicant shall evidence that he or she has passed a written examination conducted pursuant to sections 21a-7(a)(1) and 21a-8(a)(5) of the Connecticut General Statutes.
Conn. Agencies Regs. § 25-129-9