Extech Instruments 450 User manual

User's Guide
Autoranging Multimeter
plus IR Thermometer
Extech 450
Patent Pending

EX450V5.0V 10/062
Introduction
Congratulations on your purchase of the Extech 450 (part number
EX450) Autoranging Multimeter plus IR Thermometer. This meter
measures AC/DC Voltage, AC/DC Current, Resistance, Diode
Test, and Continuity plus Non-Contact IR Temperature. 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 (in this case)
750 VAC or 1000VDC.
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.
This symbol indicates there is a potential
hazard from a laser light source.
WARNING
CAUTION
MAX
1000V

EX450V5.0V 10/063
OVERVOLTAGE CATEGORY III
This meter meets the IEC 610-1-95 standard for OVERVOLTAGE
CATEGORY III. Cat III meters are protected against overvoltage
transients in fixed installation at the distribution level. Examples
include switches in the fixed installation and some equipment for
industrial use with permanent connection to the fixed installation.
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 1000V DC/750V AC, 200Vrms on
200mV range
mA AC/DC 200mA 250V fast acting fuse
A AC/DC 20A 250V fast acting fuse(30
seconds max every 15 minutes)
Resistance, Diode Test,
Continuity
250Vrms for 15sec max
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input
jack exceeds 1000V 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 the power and disconnect the test leads
before opening the cover 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. NEVER look directly at the laser light source or aim the
pointer at an eye.

EX450V5.0V 10/064
Controls and Jacks
1. IR Thermometer and laser pointer
2. 2000 count LCD display
3. HOLD button
4. SELECT button
5. Function switch
6. mA, uA and A input jacks
7. COM input jack
8. Positive input jack
9. MAX hold button (voltage and current)
10. BACKLIGHT button
11. Laser pointer button
12. Protective holster
Note: Tilt stand and battery compartment are on rear of unit.
Symbols and Annunciators
•))) Continuity
Diode test
Laser pointer
Battery status
Test lead connection
error
µ micro (10-6) (amps)
m milli (10-3) (volts, amps) A Amps
k kilo (103) (ohms) F Farads (capacitance)
M mega (106) (ohms) Ω Ohms
MAX Maximum hold V Volts
AUTO Autoranging DC Direct current
HOLD Display hold ºF Degrees Fahrenheit
ºC Degrees Centigrade

EX450V5.0V 10/065
Specifications
Function Range Resolution Accuracy
200mV 0.1mV ±(0.5% reading + 2 digits)
2V 0.001V
20V 0.01V
200V 0.1V
±(0.8% reading + 2 digits)
DC
Voltage
1000V 1V ±(1.0% reading + 3 digits)
50 to 400Hz 400Hz to 1kHz
2V 0.001V
±(1.0% reading
+ 4 digits)
±(2.5% reading
+ 8 digits)
20V 0.01V
200V 0.1V
±(1.5% reading
+ 4 digits)
±(3.0% reading
+ 8 digits)
AC
Voltage
750V 1V ±(2.0% reading
+ 6 digits)
±(3.5% reading
+ 8 digits)
200µA 0.1µA
2000µA 1µA
20mA 0.01mA
200mA 0.1mA
±(1.5% reading + 3 digits)
2A 0.001A
DC
Current
20A 0.01A ±(2.5% reading + 5 digits)
50 to 400Hz 400Hz to 1KHz
200µA 0.1µA
2000µA 1µA
20mA 0.01mA
200mA 0.1mA
±(1.8% reading
+ 8 digits)
±(3.0% reading
+ 7 digits)
2A 0.001A
AC
Current
20A 0.01A
±(3.0% reading
+ 8 digits)
±(3.5% reading
+ 10 digits)
NOTE: Accuracy is stated at 65oF to 83oF (18oC to 28oC) and less
than 75% RH.

EX450V5.0V 10/066
Function Range Resolution Accuracy
200Ω0.1Ω±(0.8% reading + 4 digits)
2kΩ0.001kΩ±(0.8% reading + 2 digits)
20kΩ0.01kΩ
200kΩ0.1kΩ
2MΩ0.001MΩ
±(1.0% reading + 2 digits)
Resistance
20MΩ0.01MΩ±(3.0% reading + 5 digits)
-58 to 518°F 1°F
Temp
(IR) -50 to270°C 1°C ±2.0% reading or ±2°C, ±4 °F
NOTE: Accuracy specifications consist of two elements:
•(% reading) – This is the accuracy of the measurement circuit.
•(+ digits) – This is the accuracy of the analog to digital converter.
Diode Test Test current of 0.3mA maximum,
open circuit voltage 1.5V DC typical
Continuity Check Audible signal will sound if the
resistance is less than 150Ω
(approx.), test current <0.7mA
IR Spectral response 6 to 16µm
IR Emissivity 0.95 fixed
IR distance ratio 8:1
Input Impedance >7.5MΩ(VDC & VAC)
AC Response Average responding
ACV Bandwidth 50Hz to 1kHz
Display 2000 count backlit liquid crystal
Overrange indication “OL” is displayed
Auto Power Off 15 minutes (approximately)
Polarity Automatic (no indication for
positive); Minus (-) sign for negative
Measurement Rate 2 times per second, nominal
Low Battery Indication “ ” is displayed if battery voltage
drops below operating voltage

EX450V5.0V 10/067
Battery One 9 volt (NEDA 1604) battery
Fuses mA, µA ranges; 0.2A/250V fast blow
A range; 20A/250V ceramic fast blow
Operating Temperature 41ºF to 104ºF (5ºC to 40ºC)
Storage Temperature -4oF to 140oF (-20oC to 60oC)
Operating Humidity Max 80% up to 87ºF (31ºC) decreasing
linearly to 50% at 104ºF(40ºC)
Storage Humidity <80%
Operating Altitude 7000ft. (2000meters) maximum.
Weight 0.753lb (342g) (includes holster).
Size 7.36” x 3.2” x 2.0” (187 x 81 x 50mm)
(includes holster)
Safety For indoor use and in accordance with
the requirements for double insulation to
IEC1010-1 (1995): EN61010-1 (1995)
Overvoltage Category III 600V and
Category II 1000V, Pollution Degree 2.

EX450V5.0V 10/068
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. If “OL” appears in the display during a measurement, the value
exceeds the range you have selected. Change to a higher range.
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.
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 green
V position.
2. Press the SELECT button to
indicate “DC” on the display.
3. Insert the black test lead banana
plug into the negative COM jack.
Insert the red test lead banana plug
into the positive Vjack.
4. 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.
5. Read the voltage in the display.

EX450V5.0V 10/069
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 green
V position.
2. Press the SELECT button to
indicate “AC” on the display.
3. Insert the black test lead banana
plug into the negative COM jack.
Insert red test lead banana plug into
the positive Vjack.
4. Touch the black test probe tip to the
neutral side of the circuit.
Touch the red test probe tip to the
“hot” side of the circuit.
5. Read the voltage in the display.

EX450V5.0V 10/0610
DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A
scale 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 2000µA DC, set the
function switch to the yellow
µA position and insert the red
test lead banana plug into the
µA/mA jack.
3. For current measurements up
to 200mA DC, set the function
switch to the yellow mA
position and insert the red test
lead banana plug into the
µA/mA jack.
4. For current measurements up
to 20A DC, set the function
switch to the yellow 20A range and insert the red test lead
banana plug into the 20A jack.
5. Press the SELECT button to indicate “DC” on the display.
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.
Note: When current measurements exceed 10 Amps the meter will
produce an audible warning tone which indicates that the
measurement time should be limited to 30 seconds or less.

EX450V5.0V 10/0611
AC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A
scale 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 2000µA AC, set the function
switch to the yellow µA
position and insert the red test
lead banana plug into the
µA/mA jack
3. For current measurements up
to 200mA AC, set the function
switch to the yellow mA
position and insert the red test
lead banana plug into the
µA/mA jack.
4. For current measurements up
to 20A AC, set the function
switch to the yellow 20A range
and insert the red test lead
banana plug into the 20A jack.
5. Press the SELECT button to indicate “AC” on the display.
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 neutral side of the circuit.
Touch the red test probe tip to the “hot” side of the circuit.
8. Apply power to the circuit.
9. Read the current in the display.
Note: When current measurements exceed 10 Amps the meter will
produce an audible warning tone which indicates that the
measurement time should be limited to 30 seconds or less.

EX450V5.0V 10/0612
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 green
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. Press the SELECT button to
indicate Ω on the display.
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.

EX450V5.0V 10/0613
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
green Ωposition.
2. Insert the black lead banana plug
into the negative COM jack
Insert the red test lead banana
plug into the positive Ωjack.
3. Press the SELECT button to
indicate on the display
4. Touch the test probe tips to the
circuit or wire you wish to check.
5. If the resistance is less than
approximately 150Ω, the audible
signal will sound. If the circuit is
open, the display will indicate “OL”.
DIODE TEST
1. Set the function switch to the
green Ωposition.
2. Insert the black test lead banana
plug into the negative COM jack
and the red test lead banana
plug into the positive Vjack.
3. Press the SELECT button to
indicate on the display.
4. Touch the test probes to the
diode under test. Forward
voltage will typically indicate
0.400 to 0.700V. Reverse
voltage will indicate “OL”.
Shorted devices will indicate
near 0V and an open device will
indicate “OL” in both polarities.

EX450V5.0V 10/0614
NON-CONTACT TEMPERATURE MEASUREMENTS
1. Set the function switch to the red IR Temp position.
2. Press the SELECT button to select ºF or ºC
3. Point the meter at the surface to be measured.
4. If needed, press the IR Laser Pointer button to locate the exact
spot being measured.
5. The area of the surface to be measured must be larger than the
spot size as determined by the distance to spot size
specification.
6. Read the temperature in the display.
(2.5cm) (5cm)
(10cm)
(20cm)
(40cm)
(80cm)
Diameter of Spot
Distance to Object
WARNING: Do not directly view or direct the laser pointer
at an eye. Low power visible lasers do not normally present a
hazard, but may present some potential for hazard if viewed
directly for extended periods of time.

EX450V5.0V 10/0615
DISPLAY BACKLIGHT
Press and hold the button for >1 second to turn on or off the
display backlight function. The backlight will automatically turn
off after 30 seconds.
MAX
Press the MAX button to activate the MAX feature in the voltage
or current functions. The display will hold the maximum reading
and will update only when a reading higher then the currently
displayed reading occurs. Press the MAX button again to
disable the feature.
HOLD
The hold function freezes the reading in the display. Press the
HOLD key momentarily to activate or to exit the hold function.
AUTO POWER OFF
The auto off feature will turn the meter off after 15 minutes.
LOW BATTERY INDICATION
The icon will appear in the lower left conner of the display
when the battery voltage becomes low. Replace the battery
when this appears.
WRONG CONNECTION INDICATION
The icon will appear in the upper right conner of the
display and the buzzer will sound whenever the positive test
lead is inserted into the 20A or uA/mA input jack and a non-
current (green, black or red) function is selected. If this occurs,
turn the meter off and reinsert the test lead into the proper input
jack for the function selected.

EX450V5.0V 10/0616
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 batteries should be removed to prevent damage
to the unit.

EX450V5.0V 10/0617
BATTERY INSTALLATION
WARNING: To avoid electric shock, disconnect the test leads
from any source of voltage before removing the battery cover.
1. Turn power off and disconnect the test leads from the meter.
2. Open the rear battery cover by removing two screws (B) using
a Phillips head screwdriver.
3. Insert the battery into battery holder, observing the correct
polarity.
4. Put the battery cover back in place. Secure with the screw.
WARNING: To avoid electric shock, do not operate the meter
until the battery cover is in place and fastened securely.
NOTE: If your meter does not work properly, check the fuses and
battery to make sure that they are still good and that they
are properly inserted.

EX450V5.0V 10/0618
REPLACING THE FUSES
WARNING: To avoid electric shock, disconnect the test leads
from any source of voltage before removing the fuse cover.
1. Disconnect the test leads from the meter.
2. Remove the protective rubber holster.
3. Remove the battery cover (two “B” screws) and the battery.
4. Remove the four “A” screws securing the rear cover.
5. Lift the center circuit board straight up from the connectors to
gain access to the fuse holders.
6. Gently remove the old fuse and install the new fuse into the
holder.
7. Always use a fuse of the proper size and value (0.2A/250V fast
blow for the 200mA range, 20A/250V fast blow for the 20A
range).
8. Align the center board with the connectors and gently press
into place.
9. Replace and secure the rear cover, battery and battery cover.
WARNING: To avoid electric shock, do not operate your meter
until the fuse cover is in place and fastened securely.
UL LISTED
The UL mark does not indicate that this product has been
evaluated for the accuracy of its readings.

EX450V5.0V 10/0619
Warranty
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be
free of defects in parts and workmanship for three years from date of
shipment (a six month limited warranty applies on sensors and cables). If it
should become necessary to return the instrument for service during or
beyond the warranty period, contact the Customer Service Department at
[phone] ext. 210 for authorization or visit our website at
www.extech.com (click on ‘Contact Extech’ and go to ‘Service Department’
to request an RA number). A Return Authorization (RA) number must be
issued before any product is returned to Extech. The sender is responsible
for shipping charges, freight, insurance and proper packaging to prevent
damage in transit. This warranty does not apply to defects resulting from
action of the user such as misuse, improper wiring, operation outside of
specification, improper maintenance or repair, or unauthorized modification.
Extech specifically disclaims any implied warranties or merchantability or
fitness for a specific purpose and will not be liable for any direct, indirect,
incidental or consequential damages. Extech's total liability is limited to
repair or replacement of the product. The warranty set forth above is
inclusive and no other warranty, whether written or oral, is expressed or
implied.
Calibration and Repair Services
Extech offers complete repair and calibration services for the
products we sell. For periodic calibration, NIST certification or
repair of an Extech product, call customer service for details on
services available for that product. Extech recommends that
calibration be performed on an annual basis to ensure
calibration integrity.
Copyright ©2006 Extech Instruments Corporation.
All rights reserved including the right of reproduction
in whole or in part in any form.

Support Hotline [phone]
Tech support: Ext. 200; Email: [email protected]
Repair/Returns: Ext. 210; Email: [email protected]
Website: www.extech.com