Extech EX320 Operating Manual

User's Guide

Mini Multimeter

with Non-Contact Voltage Detector (NCV)

Model EX320

Introduction

Congratulations on your purchase of the Extech 320 MultiMeter. The EX320 offers AC/DC
Voltage, AC/DC Current, Resistance, Diode, and Continuity testing plus a built-in non-contact
Voltage Detector. 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

MAX
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:

Function Maximum Input

V DC or V AC 600V AC and DC

mA AC/DC 200mA DC/AC

A AC/DC 10A DC/AC (for 30 seconds max. every 15 minutes

Resistance, Diode Test, Continuity 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

Model EX320 - Version 4.0 –05/2006 2

Controls and Jacks

1. AC Voltage Detector Sensor

2. AC Voltage Detector indicator light

3. LCD display

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 functions

11. RANGE button

12. HOLD button

13. Protective rubber holster (must be
removed to access the rear battery
compartment)

Display Symbols and Annunciators

•))) Continuity

Diode test

Battery status

µ micro (10

m milli (10-3) (volts, amps)

k kilo (10

M mega (10

V Volts

A Amps

Ω Ohms

AC Alternating current

DC Direct current

HOLD Display hold

AUTO Autoranging

MAX Highest reading

C, F Temperature units

-6

) (amps)

3

) (ohms)

6

) (ohms)

1

2

3

4

5

13

12

11

6

7

10A
for

30sec.

8

MAX

every
15min.
FUSED

10

9

Model EX320 - Version 4.0 –05/2006 3

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.

NON-CONTACT VOLTAGE (NCV)

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.

Model EX320 - Version 4.0 –05/2006 4