Electrical safety switch for electrical appliances

Claim 2

An electrical safety switch adapted for incorporation in an electrical appliance having a three-wire cord comprising an on/off switch connected directly to the ground line of the cord and disposed in series with a resistor and the primary coil of a transformer, which transformer is connected between the resistor and the B+ line of the cord leading to the appliance, a triac connected between the load of the appliance and the neutral line with the gate triggering the triac being connected to the transformer secondary coil to be energized thereby upon a current being present through the on/off switch, and means for matching impedance in said circuit with said gate to the impedance of the circuit and said on/off switch for providing a low current across said on/off switch.

Claim 3

A safety switch according to claim 1 wherein said means matching said impedance comprises the secondary winding of the transformer, which is connected to the neutral line, and a resistor connected in series with said secondary winding and the gate of the triac.

Claim 4

A safety switch according to claim 1 wherein the sum of the resistance of said resistor and the primary coil of said transformer produce a current through said on/off switch and ground line of less than 5 milliamperes.

Claim 5

A safety switch according to claim 3 wherein said current through said on/off switch and ground line is less than 1 milliampere.

Claim 6

An electrical safety circuit for position between an electrical appliance and the plug of the 3-wire cord for monitoring the presence of a suitable ground for the appliance prior to the energization of the appliance with the total voltage and current load to operate the same comprising: means providing a direct B+ line from the plug to the appliance, an on/off switch positioned in a circuit between the B+ line and the ground line, triggering circuit means for carrying a low voltage signal, transformer means disposed in series with said switch for producing a signal into said triggering circuit means, means between said transformer means and said switch for reducing the voltage in said switch, and a triac connected in series with the load of the appliance between the B+ line and the neutral line triggered by said signal to energize the appliance through said triac upon current passing through said on/off switch.

Claim 7

An electrical safety circuit for position between an electrical appliance and the plug of the 3-wire cord for monitoring the presence of a suitable ground for the appliance prior to the energization of the appliance with the total voltage and current load to operate the same comprising: means providing a direct B+ line from the plug to the appliance, an on/off switch positioned in a circuit between the B+ line and the ground line, triggering circuit means for carrying a low voltage signal, transformer means disposed in series with said switch for producing a signal into said triggering circuit means, means between said transformer means and said switch for reducing the voltage in said switch, and a triac connected in series with the load of the appliance between the B+ line and the neutral line triggered by said signal to energize the appliance through said triac upon current passing through said on/off switch.