Installation of lines in well tools. A well tool for use in conjunction with a subterranean well includes connectors at opposite ends of the well tool, a line extending between the connectors; at least one threaded connection at a position between the connectors; and an anti-rotation device which permits make-up of the threaded connection without relative rotation between ends of the line. A method of installing a line in a well tool includes the steps of: making-up a threaded connection at a position between end connectors of the well tool; and preventing relative rotation between ends of the line during the threaded connection making-up step, the line extending between the connectors.