An electrical control is provided with an insulated shaft extension. The insulated shaft extension is attached to a metal shaft rotatably supported in a bushing attached to the housing of the control. A hollow shaft portion of the insulated shaft extension is in concentric relationship with the metal...http://www.google.ca/patents/US4035759?utm_source=gb-gplus-sharePatent US4035759 - Electrical control having an insulated shaft extension
