37 Pa. Code § 111.4
(a) Venue in actions for claims against a Commonwealth party as defined in 42 Pa.C.S. § 8501 (relating to definitions) shall be in the county in which one of the following exists:
Local Office
For purposes of determining venue within which the Commonwealth may be subject to suit, a ‘‘local office’’ was defined so as to restrict venue to the county where the cause of action arose, not simply any county within which the Commonwealth had an office. Bogetti v. Department of Transportation, 601 A.2d 421 (Pa. Cmwlth. 1991).
Third-Party Proceedings
Section 8523 of the Judicial Code, 42 Pa.C.S. § 8523, which required actions against a Commonwealth party be brought in and only in a county in which the principal or local office of the party was located, was not applicable to third-party proceedings in which the Commonwealth was joined as a defendant by the original defendants against whom the action was brought. Chen v. Philadelphia Elec. Co., 661 A.2d 25 (Pa. Cmwlth. 1995); appeal dismissed 680 A.2d 1156 (Pa. 1996); overruled, Ribnicky v. Yerex, 701 A.2d 1348 (Pa. 1997).
This section cited in 37 Pa. Code § 111.1 (relating to service of process).