Klein Tools MM450 User manual

Auto-Ranging

Digital Multimeter

True RMS

600V

10A

50M

ENGLISH

INSTRUCTION MANUAL

True RMS

Measurement
Technology

• HIGH VISIBILITY
DISPLAY

• LEAD ALERT
PROTECTION

• DATA HOLD

• AUDIBLE
CONTINUITY

• MIN / MAX

• TEMPERATURE

• DIODE TEST

• CAPACITANCE

MM450

Ω

2m

5000573

CAT III
600V

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ENGLISH

GENERAL SPECIFICATIONS

Klein Tools MM450 is an auto-ranging, true root mean square (TRMS)
multimeter that measures AC/DC voltage, AC/DC current, and resistance. It
can also measure temperature, capacitance, frequency, duty-cycle, and test
diodes and continuity. It features lead alert protection and a high visibility,
reverse contrast LCD display with an optical sensor to automatically
optimize viewability in dark or bright ambient lighting.

• Environment:

• Operating Altitude: 6562 ft. (2000m)

• Relative Humidity: <90% non-condensing

• Operating Temp: 14°F to 140°F (-10°C to 60°C)

• Storage Temp: 14°F to 140°F (-10°C to 60°C)

• Accuracy: Values stated at 65°F to 83°F (18°C to 28°C)

• Temp Coef cient: 0.1 × (Quoted Accuracy) per °C above 28°C

or below 18°C, corrections are required when ambient working
temperature is outside of Accuracy Temp range

• Dimensions: 6.49" × 3.14" × 1.09" (165.0 × 80.0 × 27.8 mm)

• Weight: 9.24 oz. (262 g) with batteries

• Calibration: Accurate for one year

• Standards: Conforms to: UL STD 61010-1,

61010-2-030, 61010-2-033.
Certified to: CSA STD C22.2 # 61010-1,

61010-2-030, 61010-2-033.
IEC/EN/BS 61010-1, 61010-2-030,

61010-2-033, 61326-1.

• Pollution degree: 2

• Accuracy: ± (% of reading + # of least significant digits)

• Drop Protection: 6.6 ft. (2m)

• Safety Rating: CAT III 600V, Class 2, Double insulation

Indoor. DO NOT expose to moisture, rain, or snow.

CAT III: Measurement category III is applicable to test and

measuring circuits connected to the distribution part of the
building’s low-voltage MAINS installation.

• Electromagnetic Environment: IEC EN 61326-1. This

equipment meets requirements for use in basic and controlled
electromagnetic environments like residential properties,
business premises, and light-industrial locations.

Specifications subject to change.

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ELECTRICAL SPECIFICATIONS

VOLTAGE (AUTO-RANGING)

Function Range Resolution Accuracy

4.000V 1mV

AC Voltage

(V AC)

DC Voltage

(V DC)

Input Impedance: 10MΩ
Frequency Range: 50 to 400Hz
Maximum Input: 600V AC RMS or 600V DC

40.00V 10mV

400.0V 100mV
600V 1V ±(1.2% + 5 digits)

400.0mV 0.1mV

4.000V 1mV

40.00V 10mV

400.0V 100mV ±(0.8% + 3 digits)
600V 1V ±(1.0% + 3 digits)

±(1.0% + 3 digits)

±(0.5% + 5 digits)

CURRENT (AUTO-RANGING)

400.0μA 0.1μA ±(1.0% + 5 digits)
4000μA 1μA

AC Current

(μA and mA)

DC Current

(μA and mA)

Overload Protection: 500mA / 600V and 10A / 600V Fuses
Frequency Range: 50 to 400Hz
Maximum Input: µA/mA setting: 400mA AC RMS / DC
10A setting: 10A AC RMS / DC

40.00mA 0.01mA

400.0mA 0.1mA ±(1.2% + 8 digits)

4.000A 0.001A ±(2.0% + 3 digits)

10.00A 10mA ±(2.0% + 5 digits)

400.0μA 0.1μA ±(1.0% + 5 digits)
4000μA 1μA

40.00mA 0.01mA

400.0mA 0.1mA ±(1.0% + 5 digits)

4.000A 0.001A ±(2.0% + 5 digits)

10.00A 10mA ±(1.0% + 5 digits)

±(1.5% + 5 digits)

±(1.0% + 3 digits)

RESISTANCE (AUTO-RANGING)

Range Resolution Accuracy

400.0Ω 0.1Ω

4.000kΩ 1Ω

40.00kΩ 10Ω

400.0kΩ 100Ω

4.000MΩ 1kΩ

40.00MΩ 10kΩ ±(2.0% + 10 digits)

50.0MΩ 100kΩ ±(2.8% + 10 digits)

Maximum Input: 600V DC or 600V AC RMS

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±(1.2% + 5 digits)

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ENGLISH

ELECTRICAL SPECIFICATIONS

CAPACITANCE (AUTO-RANGING)

Range Resolution Accuracy

40.00nF 10pF ±(3.5% + 10 digits)

400.0nF 0.1nF
±(3.0% + 5 digits)4.000μF 1nF

40.00μF 10nF

400.0μF 0.1μF ±(3.5% + 5 digits)

Maximum Input: 600V DC or 600V AC RMS

FREQUENCY (AUTO-RANGING)

9.999Hz 0.001Hz

99.99Hz 0.01Hz

999.9Hz 0.1Hz

9.999kHz 1Hz

50.00kHz 10Hz

Sensitivity:>2V to 220V RMS
Maximum Input: 600V DC or 600V AC RMS

±(1.0% + 5 digits)

DUTY CYCLE

1.0% to 99.9%

Pulse Width: >100us, <100ms
Frequency Width: 5Hz to 10kHz
Sensitivity:>2V to 220V RMS
Maximum Input: 600V DC or 600V AC RMS

0.1% ±(1.2% + 2 digits)

TEMPERATURE

-40°F to 10°F 1°F ±(1.2% + 7°F)

11°F to 1832°F 1°F ±(1.2% + 6°F)

-40°C to -12°C 1°C ±(1.2% + 4°C)

-11°C to 1000°C 1°C ±(1.2% + 3°C)

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ELECTRICAL SPECIFICATIONS

• Diode Test: 1.8 mA max, open circuit voltage 3.9V DC

• Continuity Check: Audible signal <50Ω

• Sampling Frequency: 3 samples per second

• Auto-Power Off: After ~5 minutes of inactivity

• Overload: "OL" indicated on display, overload protection

600V RMS in all settings

• Polarity: "-" on display indicates negative polarity

• Display: 3 ¾ digit, 4000 Count LCD

WARNINGS

To ensure safe operation and service of the meter, follow these
instructions. Failure to observe these warnings can result in
severe injury or death.

• Before each use verify meter operation by measuring a known
voltage or current.

• Never use the meter on a circuit with voltages that exceed the
category based rating of this meter.

• Do not use the meter during electrical storms or in wet weather.

• Do not use the meter or test leads if they appear to be damaged.

• Probe assemblies to be used for MAINS measurements shall
meet IEC/EN 61010-031 with a voltage RATING of CAT III 600V
or better.

• Ensure meter leads are fully seated, and keep fingers away
from the metal probe contacts when making measurements.

• Do not open the meter to replace batteries while the probes
are connected.

• Use caution when working with voltages above 25V AC RMS
or 60V DC. Such voltages pose a shock hazard.

• To avoid false readings that can lead to electrical shock,
replace batteries when a low battery indicator appears.

• Do not attempt to measure resistance or continuity on a live
circuit.

• Always adhere to local and national safety codes. Use personal
protective equipment to prevent shock and arc blast injury
where hazardous live conductors are exposed.

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ENGLISH

SYMBOLS ON METER

AC/DC Voltage or Current Resistance (in Ohms)
Audible Continuity Diode
Capacitance
Duty-cycle Double Insulated Class II

%

Temperature (Fahrenheit / Celsius) Ground

°F/°

C

Voltage (Volts)

V

Backlight
Fuse (with rating below symbol)
Warning or Caution Read instructions

To ensure safe operation and service of this meter, follow all warnings
and instructions detailed in this manual.

Risk of Electrical Shock

Improper use of this meter can lead to risk of electrical shock. Follow
all warnings and instructions detailed in this manual.

Frequency

Hz

Amperage (Amps)

A

Milliamps

mA

Microamps

μA

SYMBOLS ON LCD

Data Hold Audible Continuity

H

Diode Auto Ranging

AC

Alternating Current
Low Battery Auto Power Off

MAX

Maximum Value

°F

Degrees Fahrenheit

M

Mega (value × 106)

m

mili (value × 10-3)

n

nano (value × 10-9)

A

Amps
Ohms

DC

Direct Current

MIN

Minimum Value

°C

Degrees Celsius

k

kilo (value × 103)

μ

micro (value × 10-6)

V

Volts

F

Farads

Hz

Hertz (Frequency)

%

Duty-Cycle Hazardous Voltage

Automatic

A

Backlight Adjustment

M

Manual Backlight
Adjustment

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FEATURE DETAILS

FRONT SIDE

1

7 8

10

69

12

2

3

4

5

11

BACK

13

4000 count

1.

Reverse Contrast Display
Function selector switch

2.

"10A" jack

3.

"COM" jack

4.

"VΩ" jack

5.

Backlight button

6.

"RANGE" button

7.

"MAX/MIN" button

8.

"HOLD" (Data Hold) button

9.

"SEL" (Select) button

10.

Lead Alert LEDs

11.

Optical Sensor

12.

Attachment slot for 69417

13.

Magnetic Hanger

NOTE: There are no user-serviceable parts inside meter.

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ENGLISH

FUNCTION BUTTONS

ON/OFF

To Power ON the meter rotate the Function Selector switch
OFF setting to any measurement setting. To Power OFF the meter rotate the
Function Selector switch

2

to the OFF setting. By default, the meter will

2

from the

automatically Power OFF after 5 minutes of inactivity. Reactivate meter by
pressing any button. To deactivate the automatic Power OFF feature, power
the meter ON with the SEL button
OFF is deactivated, the

symbol will not be visible in the display.

depressed. When automatic Power

10

"SEL" (SELECT) BUTTON (FOR SECONDARY FUNCTIONS)

The "SEL" button
accessible by the function selector switch

activates the secondary function for each application

10

2

. For current and voltage, it
toggles between AC and DC. For the other functions, it switches between °F
and °C, between Hz and % Duty-cycle, between Continuity and Resistance,
and between Capacitance and Diode-test. The default function for each
application is printed on the meter in white; the secondary function for each
location is printed on the meter in orange.

"HOLD" (DATA HOLD) BUTTON

Press the "HOLD" button
again to release the display and return to live measuring.

to hold the measurement on the display. Press

9

"RANGE" BUTTON

The meter defaults to auto-ranging measurement mode

. This
automatically determines the most appropriate measurement range for the
testing that is being conducted. To manually force the meter to measure in a
different range, use the "RANGE" button

1. Press the "RANGE" button

is deactivated on the LCD). Repeatedly press the "RANGE" button

(

to cycle through the available ranges, stopping once the desired range

7

is reached.

7

2. To return to auto-ranging mode, press and hold the "RANGE" button

for more than one second ( is reactivated).

.

7

to manually select measurement range

7

"MAX/MIN" BUTTON

When the "MAX/MIN" button
minimum and maximum value of the measurement as the meter continues
to take samples. The first press of the "MAX/MIN" button
Max value, the second press displays the Min value.

is pressed, the meter keeps track of the

8

displays the

8

To return to normal measuring mode, press and hold the "MAX/MIN"

for more than one second.

button

8

BACKLIGHT BUTTON

The meter defaults to Automatic Brightness mode, which adjusts the screen's
brightness based on the ambient lighting conditions detected by the Optical

Press the Backlight Button6 to enter manual high brightness mode.

Sensor

12

Press Backlight Button
Backlight Button

again to enter manual low brightness mode. Press the

6

once more to return to Automatic Brightness mode.

6

LEAD ALERT LEDs

When the Function Selector switch
the Lead Alert LEDs
inserted into the appropriate jacks. The lights will automatically turn off after

will illuminate to ensure that the test leads are

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2 minutes. To disable the Lead Alert LEDs
and turn the Function Selector switch2 to any setting other than OFF.

is rotated to a measurement setting,

2

, hold the Backlight button

11

6

NOTE: Lead Alert function will reactivate by default when the meter powers OFF

or when the Function Selector switch

8

is rotated.

2

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OPERATING INSTRUCTIONS

5/32

(4 mm)

CONNECTING TEST LEADS

Do not test if leads are improperly seated. Results could cause
intermittent display readings. To ensure proper connection, firmly
press leads into the input jack completely.

CORRECT

INCORRECT

TESTING IN CAT III / CAT IV MEASUREMENT LOCATIONS

Ensure the test lead shield is pressed firmly in place. Failure to use
the CAT III / CAT IV shield increases arc-flash risk.

5/32"

(4 mm)

TESTING IN CAT II MEASUREMENT LOCATIONS

CAT III / CAT IV shields may be removed for CAT II locations. This
will allow testing on recessed conductors such as standard wall
outlets. Take care not to lose the shields.

0.7" (18 mm)

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ENGLISH

OPERATING INSTRUCTIONS

AC/DC VOLTAGE (LESS THAN 600V)

1. Insert RED test lead into VΩ jack

COM jack
setting.

, and rotate function selector switch 2 to the V

4

, and BLACK test lead into

5

NOTE: The meter defaults to AC measurement. Press the "SEL"

button

to toggle between AC and DC modes. "AC "or "DC" on the

10

LCD indicates which mode is selected.

Black lead

Red lead

2. Apply test leads to the circuit to be tested to measure voltage.

The meter will auto-range to display the measurement in the
most appropriate range.

NOTE: If "–" appears on the LCD, the test leads are being applied
to the circuit in reverse polarity. Swap the position of the leads to
correct this.

NOTE: When in a voltage setting and the test leads are open,
readings of order mV may appear on the display. This is noise and
is normal. By touching the test leads together to close the circuit
the meter will measure zero volts.

NOTE: The Hazardous Voltage indicator appears for voltages >30V.

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OPERATING INSTRUCTIONS

AC/DC CURRENT

NOTE: The meter defaults to AC measurement. Press the "SEL"

10

button

to toggle between AC and DC modes. The AC or DC icon

on the LCD indicates which mode is selected.

1. Attach test leads to the appropriate jacks and rotate function

selector switch

2

to the appropriate setting as follows:

• For AC/DC currents >400mA and <10A: Insert RED test lead into

10A jack
function selector switch

3

, and BLACK test lead into COM jack 4, and rotate

2

to the 10A AC/DC setting.

Red lead

Black lead

• For mA AC/DC currents <400mA: Insert RED test lead into

VΩ jack
function selector switch

, and BLACK test lead into COM jack 4, and rotate

5

2

to the mA AC/DC setting.

Black lead

Red lead

• For µA DC currents <400µA: Insert RED test lead into

VΩ jack
function selector switch

, and BLACK test lead into COM jack 4, and rotate

5

2

to the µA AC/DC setting.

Black lead

Red lead

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OPERATING INSTRUCTIONS

2. To measure current: Remove power from circuit, open circuit at

measurement point, connect meter in-series in the circuit using
the test leads, and apply power to circuit.

3. Measure the current. The meter will auto-range to display the

measurement in the most appropriate range.

Do not attempt to measure more than 10A.

When measuring currents greater than 6A, a measurement

time of 30 seconds followed by 10 minutes of recovery time
is recommended.

RESISTANCE MEASUREMENTS

1. Insert RED test lead into VΩ jack

into COM jack
Continuity/Resistance

,

and rotate function selector switch 2 to the

4

setting.

, and BLACK test lead

5

NOTE: The meter defaults to Continuity testing in this mode. To

enter Resistance testing mode, press the "SEL" button
The continuity icon

will disappear from the display and the meter

10

once.

with enter auto-range

2. Remove power from circuit.

3. Measure resistance by connecting test leads to circuit. The

meter will auto-range to display the measurement in the most
appropriate range.

Black lead

Red lead

NOTE: When in a Resistance setting and the test leads are open
(not connected across a resistor), or when a failed resistor is under
test, the display will indicate O.L. This is normal.

DO NOT attempt to measure resistance on a live circuit.

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OPERATING INSTRUCTIONS

CONTINUITY

1. Insert RED test lead into VΩ jack

COM jack
Continuity/Resistance

4

, and rotate function selector switch 2 to the

setting.

, and BLACK test lead into

5

NOTE: The meter defaults to Continuity testing in this mode. Ensure

that the Continuity Testing icon
press the "SEL" button

2. Remove power from circuit.

3. Test for continuity by connecting conductor or circuit with test

leads. If resistance is measured less than 50Ω, an audible signal
will sound and display will show a resistance value indicating
continuity. If circuit is open, display will show "OL".

10

Black lead

Red lead

is visible on the display. If not,

once.

DO NOT attempt to measure continuity on a live circuit.

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ENGLISH

OPERATING INSTRUCTIONS

CAPACITANCE

1. Insert RED test lead into VΩ jack

COM jack
Capacitance/Diode

4

, and rotate function selector switch 2 to the

setting.

, and BLACK test lead into

5

NOTE: The meter defaults to Capacitance testing in this mode.

Ensure that the display reads "0 nF" with test leads open. If not,
press the "SEL" button

10

once.

2. Remove power from circuit.

3. Measure capacitance by connecting test leads across the

capacitor. The meter will auto-range to display the measurement
in the most appropriate range.

Black lead

Red lead

DIODE TEST

1. Insert RED test lead into VΩ jack

COM jack
Capacitance/Diode

4

, and rotate function selector switch 2 to the

setting.

, and BLACK test lead into

5

NOTE: The meter defaults to Capacitance testing in this mode. To

enter Diode testing mode, press the "SEL" button
Diode icon

will appear on the display.

once. The

10

2. Touch test leads to diode. A reading of 200-700mV on display

indicates forward bias, "OL" indicates reverse bias. An open
device will show "OL" in both polarities. A shorted device will
show approximately 0mV.

Black lead

Red lead

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OPERATING INSTRUCTIONS

FREQUENCY / DUTY-CYCLE

1. Insert RED test lead into VΩ jack 5 and BLACK test lead into

COM jack 4, and rotate function selector switch 2 to the
Frequency/Duty-Cycle setting.

NOTE: The meter defaults to Frequency testing in this mode. To enter
Duty-Cycle testing mode, press the "SEL" button 10 once. Ensure
that the appropriate icon (either Hz or %) appears on the display.

2. Measure by connecting test leads across the circuit.

Black lead

Red lead

TEMPERATURE

1. Insert K-type thermocouple into the VΩ 5 and COM 4 jacks

(observe the polarity markings on the thermocouple and meter), and
rotate function selector switch 2 to the Temperature setting.

NOTE: The meter defaults to Fahrenheit scale in this mode. To enter
Celsius scale, press the "SEL" button 10 once. Ensure that the
appropriate icon (either °F or °C) appears on the display.

2. To measure temperature, make contact between the thermocouple

tip and the object being measured. When thermocouple tip and
object are in thermal equilibrium, the measurement on the display
will stabilize. The meter will auto-range to display the measurement
in the most appropriate range.

K-Type

Thermocouple

Remove thermocouple before switching meter to other

measurement functions.

The thermocouple included with the original purchase is

suitable for temperatures below 356°F / 180°C only. To measure
higher temperatures, a K-type thermocouple with
the appropriate measurement range should be used.

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ENGLISH

MAINTENANCE

BATTERY REPLACEMENT

When the

1. Remove screw from battery door.

2. Replace 2 × AAA batteries (note proper polarity).

3. Replace battery door and fasten securely with screw.

T

indicator is displayed, the batteries must be replaced.

o avoid risk of electric shock, disconnect leads from any voltage

source before removing battery door.

To avoid risk of electric shock, do not operate meter while
battery door is removed.

FUSE REPLACEMENT

VΩ

A fuse may blow if more than 500mA is applied to the
or more than 10A is applied to the 10A jack

1. Remove screw from battery door.

2. Replace blown fuse(s) with:

VΩ (

μA/mA) jack5:

10A jack3: 10A/600V fast-blow (Klein Cat. No. 69032)

3. Replace battery door and fasten securely with screw.

500mA/600V fast-blow (Klein Cat. No. 69033)

. To access fuses:

3

jack 5,

To avoid risk of electric shock, disconnect leads from any
voltage source before accessing fuses.

To avoid risk of electric shock, do not operate meter while
back housing is removed.

2× AAA batteries

10A/600V fast-blow fuse

(Klein Cat. No. 69032)

500mA/600V fast-blow fuse

(Klein Cat. No. 69033)

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OPTIONAL MAGNETIC HANGER 69417

To attach 69417
Magnetic Hanger
(sold separately):

1. Open strap and

remove clip end
(not needed).

2. Loop strap through

Attachment Slot
on back of meter.

3. Close strap.

Be sure meter is turned off and wipe with a clean, dry lint-free

Do not use abrasive cleaners or solvents.

cloth.

Remove the batteries when meter is not in use for a prolonged
period of time. Do not expose to high temperatures or
humidity. After a period of storage in extreme conditions
exceeding the limits mentioned in the General Specifications
section, allow the meter to return to normal operating
conditions before using.

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REMOVE

CLEANING

STORAGE

FCC & IC COMPLIANCE

for FCC compliance information.

Canada ICES-003 (B) / NMB-003 (B)

WARRANTY

DISPOSAL / RECYCLE

Do not place equipment and its accessories in the trash.
Items must be properly disposed of in accordance with local
regulations. Please see www.epa.gov/recycle for additional
information.

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