US 4,829,289 AGranted

Static grounding and monitoring accessory

AssigneeVoltec Corporation

InventorsM. Raymond Kallman, Lawrence J. Mione, Peter Sabol

Life of this patent

Estimating the term…

Loading patent…

Abstract

Electrical monitoring circuitry simultaneously and continuously tests a three-wire ground-type AC outlet for proper line voltage, polarity of the wiring and external ground resistance. The circuitry includes a single indicating lamp, preferably a light-emitting diode, which illuminates only when the proper conditions tested for exist at the outlet. For optimum convenience, the circuitry is incorporated in a male/female outlet adaptor which, in use, is plugged into the wall outlet to be tested, thereby to establish via the phase, neutral and ground prongs of the adaptor the necessary test connections of the circuitry to the wall outlet. The adaptor includes one or more jack receptacles internally connected to the adaptor ground prong for receiving static charges from external equipment and draining same to the building ground when the light-emitting diode illuminates.

Claims6

Dependent claims

Electrical monitoring circuitry for testing the wiring of a three-wire ground-type AC outlet, said circuitry comprising first, second and third input terminal means for connection to the outlet contacts assigned, respectively, to the phase, neutral and ground wires of a building mains system;

a first conductor connected to said first input terminal mean;
a second conductor connected to said second input terminal means;
a third conductor connected to said third input terminal means;
resistive means connected between said first and third conductors for developing a voltage drop between the phase and ground wires;
voltage-responsive on-off switching means for responding to a voltage drop;
and an indicating lamp serially connected with said on-off switching means across said first and second conductors at a connection point to said first conductor beyond that of said resistive means, said on-off switching means being arranged for switching on and illuminating said indicating lamp in response to a predetermined value of a portion of the voltage drop developed across the resistance provided by said resistive means in summation with the external ground resistance at said third input terminal only when said input terminals are connected to said respective assigned outlet contacts and the latter are correctly wired to said building means system.

3 more elements

Dependencies are inferred from the claim text.