Extech Instruments CT80 User Manual page 7

The Voltage (V) Measurement Menu
The Voltage menu displays the True RMS line voltage. Use the ► button to scroll the Voltage sub-
menu (line voltage, ground-to-neutral voltage, Peak Voltage (P), and Frequency (Hz)).
The Voltage Drop (Vd) Measurement Menu
The Voltage Drop (Vd) window indicates percent (%) voltage drop (with 15A load) and the Loaded
Voltage (VL). The voltage drop sub-menu offers a load voltage result for 20A and 12A loads. Use
the ► button to scroll the sub-menu for the 12A and 20A displays.
The Impedance (Z) Measurement Menu
The Impedance (Z) window indicates the impedance in ohms of the hot conductor. The impedance
sub-menu displays the neutral (N) and ground (G) conductor impedances. Use the ► button to
move through these sub-menu items.
Note that testing ground impedance will trip a GFCI circuit.
The ASCC Measurement Menu
The ASCC window indicates the Available Short Circuit Current that the branch current can move
through a breaker in a short circuit situation.
For more specific information on the four measurement modes briefly described above, refer to the
testing examples provided later in this guide.
GFCI Button
The GFCI (Ground Fault Circuit Interrupt) feature performs two tests:
 GFCI: Faults a circuit when 6 to 9mA (from hot to ground) is detected.
 EPD (Equipment Protective Device): For breakers equipped with an EPD, the breaker trips for
ground faults greater than 30mA.
To display the GFCI main menu window, press the GFCI button. To toggle the two tests use the ►
button. Once the desired test is selected, press the GFCI button to start the test. These tests are
further detailed in the 'Testing Procedures' section below.
AFCI Button
Depressing the AFCI button displays the AFCI main menu. Two tests can be performed from this
menu: AFCI and NEUT. The AFCI tests Arc Fault Circuit Interrupting devices by creating a 106-141
amp short-duration arc between the hot and neutral conductors per UL1436. The NEUT tests for a
Shared Neutral or falsely grounded neutral conductor, which causes AFCI breakers to nuisance trip
with normal loads. This test applies 300mA between hot and neutral to ensure that the AFCI
breaker does not trip.
Refer to the testing procedures below for more detailed and application specific testing information.
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CT80-EN V1.1 08/12