General Tools and Instruments GT310 - Manual (Page 15)

The default mode is DC current measurement (indicated by the
symbol near the top left of the display). To measure AC current, press
the Select/0-9 button to change the
symbol to
~
.
Touch the test leads to two points in the circuit and read the displayed
value. A minus sign (-) at the left of the reading indicates a negative
value in DC current mode.
If applying current produces a reading of OL in uA Measurement
mode, switch to mA Measurement mode.
To switch to Manual Ranging mode, briefly press the Range button
once to remove the AUTO indication from the top left of the display.
Each subsequent press of the Range button decreases the
measurement sensitivity (increases the full-scale measurement range)
by a factor of 10 (one decimal place). If the measured current
amplitude is greater than the full-scale range, the display will show
OL. To return to Auto ranging mode, press and hold the Range button.
NON-CONTACT AC VOLTAGE/CURRENT DETECTION
(NCVD/NCCD)
Turn the rotary dial to the NCVD or NCCD position. Move the meter at
least several feet away from all wiring and briefly press the Adj. Zero
button. This maximizes the sensitivity of the NCVD or NCCD sensor.
Holding the meter in your hand, slowly move its top toward the known
or suspected source of voltage or current. As the meter approaches
the potential source of AC voltage or current, the display reading will
increase, the beeper will increase its speed, and a light (red for
voltage, green for current) behind the left side of display will flash
faster. The display reading is a relative value with no units. When the
reading peaks, briefly press the Hold button to freeze it.
To use the meter to distinguish a true “live” wire from a “ghost” live
wire, turn the rotary dial to the NCVD position, move the meter away
from all wiring, and press the Adj. Zero button. Plug the red test lead
into the red front-panel socket. Touch the tip of the lead to the
suspected live wire and note the display reading. Also touch other
suspected sources. The true live wire will produce the highest reading.
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