Extech Instruments EX330 User manual

User's Guide
Mini Multimeter
with Non-Contact Voltage Detector (NCV)
Model EX330

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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.
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.
WARNING
CAUTION
MAX
600V

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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:
Input Protection Limits
Function Maximum Input
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 minutes
Frequency, Resistance, Capacitance,
Duty Cycle, 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.

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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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Controls and Jacks
1. AC Voltage Detector Sensor
2. AC Voltage Detector indicator
light
3. LCD
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)
Display Symbols and Annunciators
n nano (10-9) (capacitance) µ micro (10-6) (amps, cap)
m milli (10-3) (volts, amps) A Amps
k kilo (103) (ohms) F Farads (capacitance)
M mega (106) (ohms) Ω Ohms
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
•))) Continuity
Diode test
Battery status
1
2
3
4
5
6
7
8
12
13
11
10
9

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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 EX310 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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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 Vjack.
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.

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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 Vjack.
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.

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AC / DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements at 10 Amps for longer
than 30 seconds. Exceeding 30 seconds may cause damage to the meter
and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack.
2. For current measurements up to 4000µA, set the function switch to the
µA position and insert the red test lead banana plug into the mA/µA jack
3. For current measurements up to 400mA, set the function switch to the
mA position and insert the red test lead banana plug into the mA/µA
jack.
4. For current measurements up to 10A, set the function switch to the 10A
range and insert the red test lead banana plug into the 10A jack.
5. Use the MODE button to select AC or DC current. The display will reflect
the selection.
6. Remove power from the circuit under test, then open up the circuit at the
point where you wish to measure current.
7. 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.
8. Apply power to the circuit.
9. Read the current in the display.

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RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under
test and discharge all capacitors before taking any resistance
measurements. Remove the batteries and unplug the line cords.
1. Set the function switch to the Ω position.
2. Insert the black test lead banana plug into the
negative COM jack.
Insert the red test lead banana plug into the
positive Ωjack.
3. Touch the test probe tips across the circuit or
component under test. It is best to disconnect
one side of the circuit under test so the rest of
the circuit will not interfere with the resistance
reading.
4. Read the resistance in the display.
CONTINUITY CHECK
WARNING: To avoid electric shock, never measure continuity on circuits or
wires that have voltage on them.
1. Set the function switch to the position.
2. Insert the black lead banana plug into the
negative COM jack.
3. Insert the red test lead banana plug into the
positive Ωjack.
4. Use the MODE button to view the icon on
the display.
5. Touch the test probe tips to the circuit or
wire you wish to check.
6. If the resistance is less than approximately
100Ω, the audible signal will sound. If the
circuit is ‘open’ (bad), the display will
indicate “OL”.