Device for determining improper reversal and/or short of ground and neutral lines and amount of impedance in ground line of a three-wire a.c. outlet

Claim 2

An AC outlet tester for determining the amount of impedance in the ground line of a three-wire AC outlet provided with three terminals connected respectively to an energized hot line, a neutral line, and a ground line, said tester comprising: circuit means for connecting between said hot line terminal and said ground line terminal, said circuit means including resistance means in series with a pulsed current generator means for causing the introduction of a current pulse from said hot line into said ground line; threshold detector means for connection between said neutral line terminal and said ground line terminal for sensing the potential developed in said ground line by the passage therethrough of said current pulse, the magnitude of said sensed potential corresponding to the amount of impedance in said ground line; said threshold detector including means for setting in said detector a threshold potential level corresponding to a predetermined amount of impedance in said ground line; said detector further including means for providing an output signal when the potential developed in said ground line exceeds said threshold level; and indicating means energized by said output signal for indicating the presence of impedance in said ground line which exceeds said predetermined amount.

Claim 3

An AC outlet tester as claimed in claim 1, wherein said threshold detector comprises a monostable amplifier including, a triggered input stage having adjustable means for adjusting said threshold level at which said input stage is triggered, and a second stage providing said output signal when said first stage is triggered, said multivibrator further including means for terminating said output signal after a predetermined time period.

Claim 4

An AC outlet tester as claimed in claim 2, wherein said outlet signal is repeated for each pulse in said test signal if the amount of impedance in said ground-neutral circuit exceeds said predetermined amount of impedance, thereby causing said indicating means to be repetitively energized.

Claim 5

An AC outlet tester for indicating an improper reversal and/or short of ground and neutral connections and for determining the amount of impedance in the ground line in a three-wire AC outlet provided with three terminals connected respectively to an energized hot line, a neutral line, and a ground line, said tester comprising: circuit means for connection between said hot line terminal and one of said neutral and said ground line terminals, said circuit means including resistance means in series with a pulsed current generator means for causing the introduction of repetitive current pulses from said hot line into said neutral line or said ground line; threshold detector means for connection between said neutral line terminal and said ground line terminal for sensing the potential developed in said neutral line or said ground line by the passage therethrough of said current pulses, the magnitude of said potential corresponding to the amount of impedance in said neutral line or said ground line; said threshold detector including switch-actuated means for setting in said detector either a first threshold potential level corresponding to a predetermined amount of impedance in said ground line or a second threshold level correspondiNg to the minimum impedance in the neutral line of a properly wired outlet; said detector further including means for providing an output signal when said sensed potential exceeds the threshold level set in said detector; and indicating means energized by said output signal indicating the presence of impedance above said threshold level, whereby said indicating means will be energized if the ground impedance exceeds said predetermined value and will not be energized if said ground and neutral connection at said test outlet are reversed and/or shorted.

Claim 6

An AC outlet tester for indicating an improper reversal and/or short of ground and neutral connections and for determining the amount of impedance in the ground line in a three-wire AC outlet provided with three terminals connected respectively to an energized hot line, a neutral line, and a ground line, said tester comprising: circuit means for connection between said hot line terminal and one of said neutral and said ground line terminals, said circuit means including resistance means in series with a pulsed current generator means for causing the introduction of repetitive current pulses from said hot line into said neutral line or said ground line; threshold detector means for connection between said neutral line terminal and said ground line terminal for sensing the potential developed in said neutral line or said ground line by the passage therethrough of said current pulses, the magnitude of said potential corresponding to the amount of impedance in said neutral line or said ground line; said threshold detector including switch-actuated means for setting in said detector either a first threshold potential level corresponding to a predetermined amount of impedance in said ground line or a second threshold level correspondiNg to the minimum impedance in the neutral line of a properly wired outlet; said detector further including means for providing an output signal when said sensed potential exceeds the threshold level set in said detector; and indicating means energized by said output signal indicating the presence of impedance above said threshold level, whereby said indicating means will be energized if the ground impedance exceeds said predetermined value and will not be energized if said ground and neutral connection at said test outlet are reversed and/or shorted.

Claim 7

An AC outlet tester as claimed in claim 4 including a test cable having one end coupled to the connection of said threshold detector to a known neutral line and another end adapted to be connected to the expected ground terminal of a test outlet, whereby said indicating means will not be energized if the ground and neutral connections at said test outlet are proper, when said test cable is connected to said ground terminal of said test outlet.

Claim 8

A three-wire ground type AC outlet tester for determining an improper reversal and/or short of ground and neutral connections at the terminals of an outlet, said terminals being connected respectively to an energized hot line, a neutral line and a ground line, said tester comprising: circuit means for connection between said hot line terminal and said neutral line terminal, said circuit means including resistance means in series with a current generator means for causing the introduction of a current pulse from said hot line into said neutral line; threshold detector means for connection between said neutral line terminal and said ground line terminal for sensing the potential developed in said neutral line by the passage therethrough of said current pulses, the magnitude of said potential corresponding to the amount of impedance in said neutral line; said threshold detector including means for setting in said detector a threshold potential corresponding to the minimum impedance in the neutral line of a properly wired outlet; said detector further including means for providing an output signal when said sensed potential exceeds said threshold level; and indicating means energized by said output signal indicating the presence of impedance in said neutral line above said threshold level.

Claim 9

A three-wire ground type AC outlet tester for determining an improper reversal and/or short of ground and neutral connections at the terminals of an outlet, said terminals being connected respectively to an energized hot line, a neutral line and a ground line, said tester comprising: circuit means for connection between said hot line terminal and said neutral line terminal, said circuit means including resistance means in series with a current generator means for causing the introduction of a current pulse from said hot line into said neutral line; threshold detector means for connection between said neutral line terminal and said ground line terminal for sensing the potential developed in said neutral line by the passage therethrough of said current pulses, the magnitude of said potential corresponding to the amount of impedance in said neutral line; said threshold detector including means for setting in said detector a threshold potential corresponding to the minimum impedance in the neutral line of a properly wired outlet; said detector further including means for providing an output signal when said sensed potential exceeds said threshold level; and indicating means energized by said output signal indicating the presence of impedance in said neutral line above said threshold level.

Claim 10

A three-wire ground type AC outlet tester as claimed in claim 6 wherein said circuit means is adapted for connection between the hot line terminal and the neutral line terminal of a known correctly wired outlet; and said tester further including: a test probe having one end connected to the point of connection of said threshold detector means to said neutral line terminal and a second end adapted for connection to the expected ground terminal of a test outlet coupled to said correctly wired outlet; whereby when said test probe is connected to the ground terminal of said test outlet, said indicating means will fail to be energized, thus indicating that the ground-neutral connections at said test outlet are properly connected.