Abstract: An innovative method of thermoplastic electrofusion welding uses a novel compressible dual resin thermoplastic welding rod. This welding rod comprises an inner core made of a soft first thermoplastic resin, a resistance wire wrapped around the inner core, and an outer coating surrounding the inner core and wire. The outer coating is made of a second thermoplastic resin that is harder than the first thermoplastic resin of the inner core. The first thermoplastic may be made of thermoplastic vulcanizate (TPV). The second thermoplastic resin may be made of a high-density polyethylene (HDPE). Because of its compressibility, this dual resin electrofusion welding rod greatly facilitates the seating of parts that are to be welded together.