Extech Instruments EX320 User Manual
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
User's Guide
Mini Multimeter
with Non-Contact Voltage Detector (NCV)
Model EX320
Visit us at www.TestEquipmentDepot.com
Introduction
MAX
Congratulations on your purchase of the Extech EX320 Meter. The EX320 offers AC/DC
Voltage, AC/DC Current, Resistance, Diode, Continuity, non-contact Voltage Detection.
Proper use and care of this meter will provide many years of reliable service.
Safety
This symbol adjacent to another symbol, terminal or operating device
indicates that the operator must refer to an explanation in the Operating
Instructions to avoid personal injury or damage to the meter.
WARNING
CAUTION
600V
SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be operated with caution. The rules
listed below must be carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the specified maximum:
V DC or V AC 600VAC and DC
mAAC/DC 500mADC/AC
AAC/DC
Resistance, Diode Test, Continuity 250V DC/AC
Temperature 250V DC/AC
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 600V above
earth ground.
4. NEVER connect the meter leads across a voltage source while the function switch is in
the current, resistance, or diode mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when
making resistance or diode tests.
6. ALWAYS turn off power and disconnect test leads before opening the covers to replace
the fuse or battery.
7. NEVER operate the meter unless the back cover and the battery and fuse covers are in
place and fastened securely.
8. If the equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired.
This WARNING symbol indicates a potentially hazardous situation, which
if not avoided, could result in death or serious injury.
This CAUTION symbol indicates a potentially hazardous situation, which
if not avoided, may result damage to the product.
This symbol advises the user that the terminal(s) so marked must not be
connected to a circuit point at which the voltage with respect to earth
ground exceeds 600V.
This symbol adjacent to one or more terminals identifies them as being
associated with ranges that may, in normal use, be subjected to
particularly hazardous voltages. For maximum safety, the meter and its
test leads should not be handled when these terminals are energized.
This symbol indicates that a device is protected throughout by double
insulation or reinforced insulation.
Input Protection Limits
Function Maximum Input
10A DC/AC (for 30 seconds max. every 15
minutes
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EX320-EU-ENG V5.1 6/09
CAUTIONS
Improper use of this meter can cause damage, shock, injury or death. Read and understand this
user manual before operating the meter.
Always remove the test leads before replacing the battery or fuses.
Inspect the condition of the test leads and the meter itself for any damage before operating the
meter.
Use great care when making measurements if the voltages are greater than 25VAC rms or
35VDC. These voltages are considered a shock hazard.
Warning! This is a class A equipment. This equipment can cause interferences in the
living quarters; in this case the operator can be required to carry out adequate
measures.
Always discharge capacitors and remove power from the device under test before performing
Diode, Resistance or Continuity tests.
Voltage checks on electrical outlets can be difficult and misleading because of the uncertainty of
connection to the recessed electrical contacts. Other means should be used to ensure that the
terminals are not "live".
If the equipment is used in a manner not specified by the manufacturer, the protection provided by
the equipment may be impaired.
This device is not a toy and must not reach children’s hands. It contains hazardous objects as well
as small parts that the children could swallow. In case a child swallows any of them, please
contact a physician immediately
Do not leave batteries and packing material lying around unattended; they can be dangerous for
children if they use them as toys
In case the device is going to be unused for an extended period of time, remove the batteries to
prevent them from training
Expired or damaged batteries can cause cauterization on contact with the skin. Always, therefore,
use suitable hand gloves in such cases
See that the batteries are not short-circuited. Do not throw batteries into the fire.
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EX320-EU-ENG V5.1 6/09
Controls and Jacks
1. AC Voltage Detector Sensor
2. AC Voltage Detector indicator light
3. LCD
4. MAX push-button
5. MODE button
6. Non-contact AC Voltage Detector test
button
7. Rotary function dial
8. 10 ampere test lead jack
9. COM test lead jack
10. Test lead jack for voltage, milli-amp, microamp, resistance
11. RANGE button
12. HOLD button
13. Protective rubber holster (must be removed
to access the rear battery compartment)
Display Symbols and Annunciators
µ micro (10-6) (amps)
m milli (10-3) (volts, amps)
k kilo (103) (ohms)
M mega (106) (ohms)
MAX Highest reading
AC Alternating current
DC Directcurrent
•))) Continuity
Diode test
Battery status
A Amps
Ohms
V Volts
AUTO Autoranging
HOLD Display hold
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EX320-EU-ENG V5.1 6/09
Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are very
dangerous and should be measured with great care.
1. ALWAYS turn the function switch to the OFF position when the meter is not in use.
2. Press the HOLD button to freeze a displayed reading
NOTE: On some low AC and DC voltage ranges, with the test leads not connected to a
device, the display may show a random, changing reading. This is normal and is
caused by the high-input sensitivity. The reading will stabilize and give a proper
measurement when connected to a circuit.
NON-CONTACT AC VOLTAGE DETECTOR
The EX320 can detect the presence of AC voltage (from 100 to 600VAC) simply by being
held very near to a voltage source.
WARNING: Test the AC voltage detector on a known live circuit before each use.
WARNING: Before using the meter in the AC Voltage Detector mode, verify that the
battery is fresh by confirming characters appear on the LCD when the function dial is
turned to any position. Do not attempt to use the meter as an AC Voltage Detector if the
battery is weak or bad.
The NCV function works on any rotary switch position.
1. Test the detector on a known live circuit before use.
2. Press and hold the NCV button for the duration of the
test. The meter will beep once when the button is
pushed.
3. Hold the top of the meter very close to the voltage
source as shown.
4. If voltage is present, the rim of the LCD display will
flash a bright orange and an audible warning will
sound.
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EX320-EU-ENG V5.1 6/09
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