Extech EX330 Operating Manual

User's Guide

Mini Multimeter

with Non-Contact Voltage Detector (NCV)

Model EX330

Introduction

Congratulations on your purchase of the Extech EX330 Meter. The EX330 offers AC/DC
Voltage, AC/DC Current, Resistance, Diode, Continuity, non-contact Voltage Detection,
Capacitance, Frequency, Duty Cycle, and Temperature (Type K) functions. 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:

V DC or V AC 600V AC and DC

mA AC/DC 500mA DC/AC

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

Frequency, Resistance, Capacitance, Duty
Cycle, Diode Test, Continuity

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

minutes

250V DC/AC

2

Model EX330 - Version 4.1 – 08/06

Controls and Jacks

1. AC Voltage Detector Sensor

2. AC Voltage Detector indicator light

3. LCD display

4. RELATIVE 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,
micro-amp, resistance, capacitance,
frequency, and temperature functions

11. RANGE button

12. HOLD button

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

1

2

3

4

5

6

7

8

Display Symbols and Annunciators

•))) Continuity
Diode test

Battery status

n nano (10
µ micro (10
m milli (10
k kilo (10
M mega (10
Hz Hertz (frequency) V Volts
% Percent (duty ratio) REL Relative
AC Alternating current AUTO Autoranging
DC Direct current HOLD Display hold
ºF Degrees Fahrenheit ºC Degrees Centigrade

-9

) (capacitance)

-6

) (amps, cap)

-3

) (volts, amps) A Amps

3

) (ohms) F Farads (capacitance)

6

) (ohms) Ω Ohms

13

12
11

10

9

3

Model EX330 - Version 4.1 – 08/06

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 EX330 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.

4

Model EX330 - Version 4.1 – 08/06

AC VOLTAGE MEASUREMENTS

WARNING: Risk of Electrocution. The probe tips

may not be long enough to contact the live parts
inside some 240V outlets for appliances because
the contacts are recessed deep in the outlets. As a
result, the reading may show 0 volts when the
outlet actually has voltage on it. Make sure the
probe tips are touching the metal contacts inside
the outlet before assuming that no voltage is
present.

CAUTION: Do not measure AC voltages if a motor
on the circuit is being switched ON or OFF. Large
voltage surges may occur that can damage the
meter.

1. Set the function switch to the VAC position.

2. Insert the black test lead banana plug into
the negative COM jack.
Insert red test lead banana plug into the
positive V jack.

3. Touch the black test probe tip to the
neutral side of the circuit.

4. Touch the red test probe tip to the “hot” side of circuit.

5. Read the voltage in the display.

6. If the measured AC voltage exceeds the highest range of the meter (refer to the
specification table) an audible tone will sound.

DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or

OFF. Large voltage surges may occur that can damage the meter.

1. Set the function switch to the VDC position.

2. Insert the black test lead banana plug into the
negative COM jack.
Insert the red test lead banana plug into the
positive V jack.

3. Touch the black test probe tip to the negative
side of the circuit.
Touch the red test probe tip to the positive side
of the circuit.

4. Read the voltage in the display.

5

Model EX330 - Version 4.1 – 08/06