General Tools and Instruments CT101 - Manual (Page 4)

Insert one probe into the narrow (“hot”)
slot of the receptacle and the other into
the wide (neutral) slot. Either probe can
go into either slot. If the line is “hot”,
the orange neon bulb at the end of the
tester will glow.
To test whether the circuit is grounded,
insert one probe into the narrow (“hot”)
slot and the other into the ground slot.
Be sure to push the probe all the way
into the ground slot to be sure that it
makes contact. The neon bulb will glow
if the receptacle is grounded. Then test
between the wide (neutral) and ground
slots. The neon bulb should not glow.
Note: The CT101 cannot indicate the
quality of a ground, reversed ground
wiring, two hot wires in a circuit, or
more than one wiring fault.
Two-Wire AC Outlets
and Power Cords
Insert the probes into the
two slots. The neon bulb will glow if the
circuit is “live”. To determine which slot
is “hot”, insert one probe into the
narrow slot and touch the other probe
to the metal mounting screw. If the bulb
glows, the screw is grounded, the
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