Patent ID: 6867703
Filing Date: 2005-03-15
Classification: G08B,H02H

Abstract:
1. A safety protection circuit for indicating ground metal contact of an electrically operated power tool, comprising: a low voltage power supply connected at one end to the hot wire of a three-wire electrical power source for said electrically operated power tool, and at its other end to commonly connected anodes of first and second indicators; wherein the cathode of said first indicator is connected to the body of said electrically operated power tool through a first diode, and the cathode of said second indicator is connected to the ground wire of a three-wire electrical power source for said electrically operated power tool through a second diode; wherein said first indicator will indicate to the operator of said power tool when it has contacted grounded metal, in use, and said second indicator will indicate to the operator of said power tool that the tool is powered properly; wherein the voltage drop across said first indicator has a first magnitude, and the voltage drop across said second indicator has a second magnitude, and wherein said first magnitude is equal to or less than said second magnitude; and wherein said low voltage power supply includes an isolating means for isolating the power source for said electrically operated power tool from said safety protection circuit.