TANK GROUND CONNECTOR MACLEAN Standard 1/2-13 UNC-2A thread studs and flat surfaces allow for single wrench installation to ground distribution transformer tanks and other apparatus. Vice type design can be installed with a ratchet winch on an unbroken ground wire, eliminating the chance of a loose connection due to "splicing" of the ground wire. Bolt thread: 5/16. Bolt hex head 9/16. 3/8" Internal Thread