Patents by Inventor John K. Johnston

John K. Johnston has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Ground fault circuit interruptor test apparatus
    Patent number: 4135129
    Abstract: An electrical testing device adapted to open a circuit upon reaching a predetermined leakage current, including means for generating a leakage current, switching means for applying the leakage current to an electrical circuit and time control means operative to limit the leakage current to the circuit so as to alter the time current characteristic of the leakage current.
    Type: Grant
    Filed: February 10, 1977
    Date of Patent: January 16, 1979
    Inventors: John K. Johnston, Frederick A. Edwards