Extech Instruments EX310 User manual

User's Guide
Mini Multimeter
with Non-Contact Voltage Detector (NCV)
Model EX310

Model EX310-EU-ENG – V7.2– 05/2008
2
Introduction
Congratulations on your purchase of the Extech EX310 MultiMeter. The EX310
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.
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

Model EX310-EU-ENG – V7.2– 05/2008
3
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 200mA DC/AC
A AC/DC 10A DC/AC (for 30 seconds max. every 15
mins.)
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.

Model EX310-EU-ENG – V7.2– 05/2008
4
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.
•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.

Model EX310-EU-ENG – V7.2– 05/2008
5
Controls and Jacks
1. AC Voltage Detector Sensor
2. AC Voltage Detector indicator light
3. LCD
4. Non-contact AC Voltage Detector
test button
5. Rotary function dial
6. 10 ampere test lead jack
7. COM test lead jack
8. Test lead jack for voltage, milliamp,
resistance/continuity, and diode
functions
9. Protective rubber holster (must be
removed to access the rear battery
compartment)
Symbols
•))) Continuity
Diode
Battery status
AC
DC
m milli (10-3) (volts, amps)
k kilo (103) (ohms)
V Volts
A Amps
Ω Ohms
AC Alternating current
DC Direct current
V/ /mA
CATII-600V
EX310
MultiMeter
1
2
3
4
5
6
7
8
9

Model EX310-EU-ENG – V7.2– 05/2008
6
Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are
very dangerous and should be measured with great care.
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.
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 EX310-EU-ENG – V7.2– 05/2008
7
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 600 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.
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 highest 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. Move the
function switch to successively lower VDC
positions to obtain a higher resolution reading.

Model EX310-EU-ENG – V7.2– 05/2008
8
BATTERY VOLTAGE TEST
CAUTION: Do not measure batteries while they are installed in the devices
they are powering. The batteries must be removed from installations before
tests can be made.
1. Set the function switch to the 1.5V or 9V
BAT switch position. Use the 1.5V position
for ‘AAA’, ‘AA’, ‘C’, ‘D’, and other 1.5V
batteries. Use the 9V position for square 9V
transistor batteries.
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 battery. Touch the red test probe
tip to the positive side of the battery.
4. Read the voltage in the display.
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 200mA AC or DC, set the function
switch to the 200m AAC or ADC position and insert the red test lead
banana plug into the mA jack.
3. For current measurements up to 10A AC or DC, set the function switch
to the 10A AAC or 10A ADC position and insert the red test lead banana
plug into the 10A jack.
4. Remove power from the
circuit under test, then open
up the circuit at the point
where you wish to measure
current.
5. 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.
6. Apply power to the circuit.
7. Read the current in the
display.
1.50
V/ /mA
CATII - 600V
EX310
MultiMeter
V

Model EX310-EU-ENG – V7.2– 05/2008
9
RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under test
and discharge all capacitors before taking any resistance measurements.
1. Set the function switch to the highest Ω position.
2. Insert the black test lead banana plug into the negative COM jack.
3. Insert the red test lead banana plug into the
positive Ωjack.
4. Touch the test probe tips across the circuit or
part under test. It is best to disconnect one side
of the part under test so the rest of the circuit
will not interfere with the resistance reading.
5. Read the resistance in the display. Move the
function switch to successively lower Ω
positions to obtain a higher resolution reading.
CONTINUITY CHECK
WARNING: To avoid electric shock, never measure continuity on circuits
that have a voltage potential.
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. Touch the test probe tips to the circuit or
wire you wish to check.
5. If the resistance is less than
approximately 100Ω, the audible signal
will sound. If the circuit is open, the
display will indicate “1___”.

Model EX310-EU-ENG – V7.2– 05/2008
10
DIODE TEST
1. Set the function switch to the
position.
2. Insert the black test lead banana plug
into the negative COM jack and the red
test lead banana plug into the positive
jack.
3. Touch the test probes to the diode
under test.
4. A good diode will indicate approx. 700
ohms for the forward test and “1___”
for the reverse test.
5. A shorted diode will indicate the same
value of resistance in both the reverse
and forward test directions. An open
diode will indicate “1___” in both test
directions.