Klein Tools MM325 Manual-Ranging Digital Multimeter

Key Features

• ?️ LEAD ALERT PROTECTION
• ? DATA HOLD
• ? AUDIBLE CONTINUITY
• ? BATTERY TEST
• ⚡ DIODE TEST
• ? AUTO POWER-OFF

Specifications: 600V~, 10A=, 2MΩ, 2m Drop Protection

(See page 13 for Español, page 25 for Français)

A front view of the Klein Tools MM325 digital multimeter is shown, displaying the LCD screen, function selector dial, buttons, and input jacks. Certifications include CE, UK CA, ETL LISTED, and Intertek 5000573, with a CAT III 600V rating.

General Specifications

The Klein Tools MM325 is a manual-ranging multimeter that measures AC/DC voltage, DC current, and resistance. It can also test batteries, diodes, and continuity.

• Environment: Indoors. DO NOT expose to moisture, rain, or snow.
• Operating Altitude: 6562 ft. (2000m)
• Relative Humidity: <80% non-condensing
• Operating Temp: 32° to 104°F (0° to 40°C)
• Storage Temp: 14° to 140°F (-10° to 60°C)
• Accuracy: Values stated at 65° to 83°F (18° to 28°C)
• Temp Coefficient: 0.1 x (Quoted Accuracy) per °C above 28°C or below 18°C; corrections are required when ambient working temp is outside of Accuracy Temp range
• Dimensions: 6.41" x 3.13" x 1.83" (162.7 × 79.4 × 46.6 mm)
• Weight: 8.8 oz. (250 g)
• Calibration: Accurate for one year
• Standards: IEC EN 61010-1, 61010-2-030, 61010-2-033. IEC EN 61326-1, 61326-2-2. Conforms to UL STD.61010-1, 61010-2-030, 61010-2-033. Certified to CSA STD.C22.2 NO. 61010-1, 61010-2-030, 61010-2-033.
• 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

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.

Specifications subject to change.

Electrical Specifications

• ⚡ Diode Test: Approx. 1.0mA, open circuit voltage 2.0V DC
• ? Continuity Check: Audible signal <50Ω
• ? Battery Test: 9V (approx. 20mA, 450Ω load); 1.5V (approx. 15mA, 100Ω load)
• Sampling Frequency: 2 samples per second
• Overload: "OL" indicated on display, overload protection 600V RMS in all settings
• Polarity: "-" on display indicates negative polarity
• Display: 3 ½ digit, 2000 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.
• Use only with ⚡ CAT III or ⚡ CAT IV rated test leads.
• Probe assemblies to be used for MAINS measurements should meet EN61010-031 standard, rated ⚡ CATIII 600V, 10A 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.

Symbols on Meter

• AC: Alternating Current
• DC: Direct Current
• Ω: Resistance (in Ohms)
• ? Ground
• ⚡ Diode
• ? Audible Continuity
• ?️ Fuse (with rating below symbol)
• Double Insulated Class II
• ? Backlight
• ℹ️ Read Instructions

Warning or Caution: 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.

Symbols on LCD

• H: ? Data Hold
• ? Audible Continuity
• ⚡ Diode
• ? Low Battery
• ⚡ Hazardous Voltage
• ? Auto Power-Off

Feature Details

A front view of the Klein Tools MM325 digital multimeter is shown, with numbered components:

1. 2000 count LCD display
2. Function selector switch
3. "10A" jack
4. "COM" jack
5. "VΩ" jack
6. "HOLD" (? Data Hold) button
7. ? Backlight button
8. ⚡ Lead Alert LEDs

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

Function Buttons

ON/OFF

Power-ON: Rotate the Function Selector switch 2 from the OFF setting to any measurement setting.

Power-OFF: Rotate the Function Selector switch 2 to the OFF setting.

Auto Power-OFF: By default, the meter will automatically Power-OFF after 15 minutes of inactivity. Reactivate meter by pressing any button. To deactivate the automatic Power OFF feature, power the meter ON with the "HOLD" button 6 depressed. When automatic Power OFF is deactivated, the ? Auto Power-OFF symbol will not be visible in the display.

HOLD (DATA HOLD)

Press the "HOLD" button 6 to hold the measurement on the display. Press again to release the display and return to live measuring.

BACKLIGHT

Press and hold the Backlight button 7 for more than one second to turn the backlight on or off. Backlight automatically turns off after approximately 3 minutes.

LEAD ALERT LEDs

When the Function Selector switch 2 is rotated to a measurement setting, the ⚡ Lead Alert LEDs 8 will illuminate green to ensure that the test leads are inserted into the appropriate jacks. The lights will automatically turn off after 2 minutes. To disable the Lead Alert LEDs 8, power the meter ON while holding the Backlight button 7.

NOTE: Lead Alert function will reactivate by default when the meter powers OFF or when the Function Selector switch is rotated.

Operating Instructions

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.

[Incorrect Connection] vs. [Correct Connection] diagram.

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.

Diagram showing CAT III/IV probe tip shielding.

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.

Diagram showing CAT II probe tip without shielding.

AC Voltage (Less Than 600V)

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 highest V AC (V~) setting (600V).
2. Measure voltage and rotate the Function Selector Switch to successively lower V AC (V~) settings to obtain higher resolution measurements.

NOTE: The ⚡ Hazardous Voltage indicator will appear for voltages >30V.

NOTE: Do not attempt to measure more than 600V or 200mA.

Diagrams showing jack connections and dial settings for AC Voltage measurement.

DC Voltage (Less Than 600V)

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 highest V DC (V) setting (600V).
2. Measure voltage and rotate the Function Selector Switch to successively lower V DC (V) settings to obtain higher resolution measurements.

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 will appear for voltages >30V.

NOTE: Do not attempt to measure more than 600V or 200mA.

Diagrams showing jack connections and dial settings for DC Voltage measurement.

DC Current (200mA to 10A)

1. For DC currents more than 200mA and less than 10A, insert RED test lead into 10A jack 3, and BLACK test lead into COM jack 4, and rotate Function Selector Switch 2 to the 10A DC setting.

Diagrams showing jack connections and dial settings for DC Current (10A) measurement.

DC Current (Less Than 200mA)

1. For mA DC currents less than 200mA, insert RED test lead into VΩ jack 5, and BLACK test lead into COM jack 4, and rotate Function Selector Switch 2 to the highest mA DC setting (200mA).
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.

NOTE: If measuring mA, the Function Selector Switch 2 may be rotated to successively lower mA DC settings to obtain higher resolution measurements.

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.

Diagrams showing jack connections and dial settings for DC Current (mA) measurement.

Resistance Measurements

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 highest Ω setting (2MΩ).
2. Remove power from circuit.
3. Measure resistance by connecting test leads to circuit and rotating the Function Selector Switch 2 to successively lower Ω settings to obtain higher resolution measurements.

Diagrams showing jack connections and dial settings for Resistance measurement.

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 "OL". This is normal.

DO NOT attempt to measure resistance on a live circuit.

Continuity

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 ? setting.
2. Remove power from circuit.
3. Test for continuity by connecting conductor or circuit with test leads. If resistance is measured less than 100Ω, an audible signal will sound and display will show a resistance value indicating continuity. If circuit is open, display will show "OL".

Diagrams showing jack connections and dial settings for Continuity test.

DO NOT attempt to measure continuity on a live circuit.

Diode Test

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 ⚡ setting.
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.

Diagrams showing jack connections and dial settings for Diode Test.

Battery Test

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 1.5V or 9V battery test setting.
2. Connect BLACK lead to negative, and RED lead to positive terminal of battery.
3. Measure voltage on display; batteries in good condition should be within approx. 10% of rated voltage.

Diagrams showing jack connections and dial settings for Battery Test.

Maintenance

Battery Replacement

When the ? indicator is displayed, the batteries must be replaced.

1. Remove screw from battery door.
2. Replace 2 x AAA batteries (note proper polarity).
3. Replace battery door and fasten securely with screw.

To 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

A fuse may blow if more than 200mA is applied to the VΩ jack 5, or more than 10A is applied to the 10A jack 3. To access fuses:

1. Remove screw from battery door.
2. Replace blown fuse(s) with:
   • VΩ (μA/mA) jack 5: 200mA/600V fast-blow, interrupting rating 1kA (Klein Cat. No. 69031)
   • 10A jack 3: 10A/600V fast-blow, interrupting rating 10kA (Klein Cat. No. 69032)
3. Replace battery door and fasten securely with screw.

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.

Illustration showing battery compartment with 2x AAA batteries and locations for 200mA and 10A fuses.

Cleaning, Storage, Compliance, Warranty, Disposal, Customer Service

Cleaning

Be sure meter is turned off and wipe with a clean, dry lint-free cloth. Do not use abrasive cleaners or solvents.

Storage

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.

FCC & IC Compliance

See this product's page at www.kleintools.com for FCC compliance information. Canada ICES-003 (B) / NMB-003 (B).

Warranty

www.kleintools.com/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.

Customer Service

KLEIN TOOLS, INC.
450 Bond Street
Lincolnshire, IL 60069
1-800-553-4676
customerservice@kleintools.com
www.kleintools.com