Importance

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Abstract

Safety apparatus for indicating a live alternating current voltage condition in an insulated electrical conductor having a central conductor wire comprises: an electrically conductive external sheath extending along a predetermined length of the insulation forming with the central conductor wire a capacitive alternating current path across the insulation; and a signal generating circuit including a full-wave rectifier connected directly between the sheath and ground. A capacitor and a neon or other gas discharge bulb characterized by avalanche breakdown at a predetermined voltage are connected in parallel with the rectifier. Optionally, a piezo electric or other sound-generating device may be in series with the neon bulb. When the central conductor wire is energized at 1000 volts AC or above, the bulb flashes, and the optional sound generator activates, at a frequency dependent on the length of the external sheath along the insulation. The external sheath functions as an outer plate for the capacitance across the insulation, and is a separate electrode slidably engageable with the outer surface of the insulation. The electrode comprises an inner, tubular, metallic element engageable with the insulation, with bell-shaped ends, and an outer tubular shell of insulating material.

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First Claim