Sughrue, Mion, Zinn, Macpeak & Seas
Non-grounding checking system
 The grounding of an electrical apparatus is monitored by a primary circuit which is inductively coupled to a coil connected in series between the grounding line of the power cord and a grounding terminal on the electrical apparatus to which a second grounding line is connected. 
Sumitomo Electric Industries, Ltd.
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Kenichi Shinya Junichi
Yoshida Takenaka Hiramoto