61 Pa. Code § 31.16
A contractor who, under a binding agreement with his customer, acts in the capacity as an agent is subject to this chapter in the same manner as he would if the agency relationship did not exist.
Example: "X" Contractor and "Y" Public Utility enter an agency contract for the construction of an electrical generation station. The agency contract provides that "X" Contractor shall purchase all equipment, materials and supplies as agent for "Y" Public Utility. The exemption available to "X" Contractor is limited to the purchase of machinery, equipment and parts thereof which upon installation are directly used in generating and transmission of electricity. "X" Contractor is not entitled to the same exemption as that of "Y" Public Utility.
61 Pa. Code § 31.16
This section cited in 61 Pa. Code § 31.11 (relating to definitions); 61 Pa. Code § 46.3 (relating to construction contractor installing stained glass windows); 61 Pa. Code § 46.7 (relating to nonresident contractors); 61 Pa. Code § 46.8 (relating to industrialized housing); and 61 Pa. Code § 58.13 (relating to carpeting and other floor coverings).