A grounding clamp uses a spring driving a piston mounted movable jaw as a safety lockout. The movable jaw and a fixed jaw, which may include teeth, form a conductor clamp. The ground clamp mounts on the end of a hot stick to provide for electrically insulated remote operation of the ground clamp by a lineman holding the hot stick and pulling on, or releasing, a lever arm on the hot stick. The system provides increased safety for the lineman as the spring providing the spring loading of the clamp has a high spring force to overcome, thus providing the lockout. The lever arm on the hot stick tool provides mechanical advantage to overcome the spring force and thus release the lockout. The lineman cannot usefully operate the ground clamp manually without the hot stick due to spring force lockout.