Extech Instruments EX310-NIST User manual

USER MANUAL
Mini Multimeter
with Non-Contact Voltage Detector (NCV)
Model EX310

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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. For copies of this user
manual in other languages please visit the www.extech.com website.
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.
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
mAAC/DC
200mA DC/AC
AAC/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.
WARNING
CAUTION
MAX
600V

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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. Repair or replace any damage before use.
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 interference to devices in the
home; in this case the operator can be required to carry out adequate measures to prevent
interference.
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 children could swallow. In case a child swallows any of the parts,
please contact a physician immediately.
Do not leave batteries and packing material unattended; they can be dangerous for children.
In case the device is going to be unused for an extended period of time, remove the batteries
to prevent them from draining.
Expired or damaged batteries can cause cauterization on contact with skin. Always use
suitable hand protection.
See that the batteries are not short-circuited. Do not throw batteries into fire.

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Description
1. AC Voltage Detector Sensor
2. AC Voltage Detector indicator light
3. Display (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
ΩOhms
AC Alternating current
DC Direct current

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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.
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 (NCV)
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 and the battery icon will appear briefly
before the display goes blank.
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 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.
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.

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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 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.
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 Ωposition.
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 Ωpositions to obtain a higher resolution reading.

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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 100Ωthe audible signal
will sound. If the circuit is open, the display will indicate “1___”.
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.

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Maintenance
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before
removing the back cover or the battery or fuse covers.
WARNING: To avoid electric shock, do not operate your meter until the battery and fuse covers are
in place and fastened securely.
This MultiMeter is designed to provide years of dependable service, if the following care instructions
are performed:
1. KEEP THE METER DRY. If it gets wet, wipe it off.
2. USE AND STORE THE METER IN NORMAL TEMPERATURES. Temperature extremes can
shorten the life of the electronic parts and distort or melt plastic parts.
3. HANDLE THE METER GENTLY AND CAREFULLY. Dropping it can damage the electronic
parts or the case.
4. KEEP THE METER CLEAN. Wipe the case occasionally with a damp cloth. DO NOT use
chemicals, cleaning solvents, or detergents.
5. USE ONLY FRESH BATTERIES OF THE RECOMMENDED SIZE AND TYPE. Remove old or
weak batteries so they do not leak and damage the unit.
6. IF THE METER IS TO BE STORED FOR A LONG PERIOD OF TIME, the battery should be
removed to prevent damage to the unit.

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BATTERY INSTALLATION and LOW BATTERY INDICATION
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before
removing the battery cover. Do not operate meter unless the battery cover is in place.
LOW BATTERY INDICATION
The icon will appear in the lower left-hand corner of the display when the battery voltage
becomes low. Replace the batteries when this appears.
BATTERY REPLACEMENT
1. Disconnect the test leads from the meter.
2. Remove the protective rubber holster. See diagram.
3. Remove the Phillips head screw located on the lower back of the instrument.
4. Remove the fuse/battery compartment cover to access the battery. See diagram.
5. Replace the 9V battery observing polarity.
6. Secure the fuse/battery compartment cover using the Phillips head screw.
7. Place the protective rubber holster on the meter.
Never dispose of used batteries or rechargeable batteries in household waste.
As consumers, users are legally required to take used batteries to appropriate
collection sites, the retail store where the batteries were purchased, or wherever
batteries are sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to take end-of-
life devices to a designated collection point for the disposal of electrical and electronic equipment.
Other Battery Safety Reminders
oNever dispose of batteries in a fire. Batteries may explode or leak.
oNever mix battery types. Always install new batteries of the same type.
1. Removable Rubber Holster
2. Meter
3. Battery
4. Fuses
5. Compartment Cover
6. Rubber Holster