Conn. Gen. Stat. § 12-412i

(b) As used in this section: (1) “Manufacturing” means the activity of converting or conditioning tangible personal property by changing the form, composition, quality or character of the property for ultimate sale at retail or use in the manufacturing of a product to be ultimately sold at retail. Changing the quality of property shall include any substantial overhaul of the property that results in a significantly greater service life than such property would have had in the absence of such overhaul or with significantly greater functionality within the original service life of the property, beyond merely restoring the original functionality for the balance of the original service life; (2) “fabricating” means to make, build, create, produce or assemble components or tangible personal property so that they work in a new or different manner; (3) “processing” means the physical application of the materials and labor necessary to modify or change the characteristics of tangible personal property; (4) “machinery” means the basic machine itself, including all of its component parts and contrivances such as belts, pulleys, shafts, moving parts, operating structures and all equipment or devices used or required to control, regulate or operate the machinery, including, without limitation, computers and data processing equipment, together with all replacement and repair parts therefor, whether purchased separately or in conjunction with a complete machine, and regardless of whether the machine or component parts thereof are assembled by the taxpayer or another party; (5) “equipment” means any device separate from machinery but essential to a manufacturing, processing or fabricating process; and (6) “measuring or testing” includes both nondestructive and destructive measuring or testing, and the alignment and calibration of machinery, equipment and tools, in the furtherance of the manufacturing, processing or fabricating of tangible personal property.

(c) The gross receipts from the sale of and the storage, use and consumption in this state of the items set forth in subsection (a) of this section shall be exempt from the taxes imposed by this chapter, to the following extent: (1) For sales made on or after January 1, 1993, and prior to July 1, 1993, ten per cent of the gross receipts from such items; (2) for sales made on or after July 1, 1993, and prior to July 1, 1994, twenty per cent of the gross receipts from such items; (3) for sales made on or after July 1, 1994, and prior to July 1, 1995, thirty per cent of the gross receipts from such items; (4) for sales made on or after July 1, 1995, and prior to July 1, 1996, forty per cent of the gross receipts from such items; and (5) for sales made on or after July 1, 1996, fifty per cent of the gross receipts from such items.

(d) The burden of proving that an item is subject to the exemption set forth in this section is upon the person who makes the sale unless he takes from the purchaser a certificate to the effect that the property is subject to such exemption. The certificate relieves the seller from the burden of proof only if taken in good faith by the seller. The certificate shall be signed by and bear the name and address of the purchaser. The certificate shall be substantially in such form as the commissioner prescribes.

(e) If a purchaser who gives a certificate makes any use of the property other than the purposes set forth in this section, the use shall be deemed a use by the purchaser in accordance with this chapter, as of the time the property is first used by him, and the property shall be taxable to such purchaser in accordance with this chapter.