EXTECH MA145 Mini Clamp Meters + NCV

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AC/DC Current clamp with 0.8″ (22mm) jaw size and high accuracy measuring current up to 300A. Advanced feature of Low Pass Filter (LPF) for accurate measurement of variable frequency drive signals. Built-in Non-Contact Voltage (NCV) Detector allows for quick detection of live voltage. Smart Auto Sense feature enables the MA145 to recognize the input (within a given function) and automatically switch to the correct mode of operation (i.e. AC to DC Current measurement).

  • True RMS for accurate readings of noisy, distorted or non-sinusoidal waveforms
  • MA145 – AC/DC Current and Zero function for accurate DC measurements
  • Compact 0.8″ (22mm) jaw size accommodates conductors up to 300MCM and allows measurements in tight locations
  • Unique Smart Auto Sense feature
  • Low Pass Filter (LPF) for accurate measurement of variable frequency drive signals
  • Built-in Non-Contact Voltage (NCV) detector
  • Inrush current measurement
  • 6000 count backlit LCD display
  • Smart Data Hold: Audiovisual alert when a new reading exceeds 50 digits of a held reading
  • Low battery indicator and Auto Power Off feature
  • CAT III-600V safety rating
  • Complete with carrying case and two LR44 batteries


PDF Logo    MA140_MA145 Datasheet
PDF Logo    MA145 User Manual
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EXTECH MA145 Specifications:


Function Range Resolution Accuracy (of reading)
50~100Hz 100~400Hz

AC Current

60.00 A 0.01 ± (1.5% + 25 digits) < 3A

± (1.5% + 5 digits) ≥ 3A

± (2.5% + 25 digits) < 3A

± (2.5% + 5 digits) ≥ 3A

300.0 A 0.1
Function Range Resolution Accuracy (of reading)

DC Current

60.00 A (1) 0.01 ± (1.5% + 10 digits) (2)
300.0 A 0.1 ± (1.5% + 5 digits)
(1) < 0.3A variation when measuring in varying directions

(2)  Add 10d to accuracy in AUTO AC/DC sense mode

Function Range Resolution Accuracy (of reading) 50Hz/60Hz
Low Pass Filter (LPF) 60.00 A 0.01 ± (3.5% + 25 digits) < 3A

± (3.5% + 5 digits) ≥ 3A

300.0 A 0.1
Cut‐off frequency (‐3db): 160Hz (approximately)  Attenuation characteristic: ‐24db per octave (approximately)
Function Range Resolution Accuracy (of reading)
Inrush Current 300.0 A 0.1 ± (3.5% + 5 digits)
Integration time: 100ms Trigger current (threshold): 5A
Voltage Detector  




The tip of the clamp offers the optimum sensitivity


  • Display                                6000‐count Multi‐Function LCD
  • Over‐range indication       “OL” or “‐OL” is displayed
  • Conversion rate  2 updates per second
  • Maximum conductor size  22mm (0.87”) in diameter
  • Auto Power OFF                 After 20 minutes (can be disabled)
  • Operating Temperature and Humidity

0~30°C (32~86°F); 80%RH maximum

30~40°C (86~104°F); 75%RH maximum

40~50°C (104~122°F); 45%RH maximum

  • Storage Temperature and Humidity =
    • -20°~60°C (‐4°~140°F); 80%RH maximum
  • Temperature Coefficient  
    • 0.2 x specified accuracy / °C, < 18°C (64.5°F), > 28°C (82.4°F)
  • Operating Altitude              2000m (6562ft.)
  • Battery power                    (2) LR‐44 1.5V batteries (battery life 20 hours typical)
  • Weight                                140g (4.9 oz.)
  • Dimensions                         60 x 147 x 31.5mm (2.4 x 5.8 x 1.2”)
  • Safety Standards                For indoor use and in accordance with the requirements for double insulation to:
    • EN61010‐1,
    • EN61010‐2‐030,
    • EN61010‐2‐032,
    • EN61326‐ 1;
    • EN61010‐1 Over‐voltage CAT III 600V, Pollution Degree 2
  • Shock and Vibration           Sinusoidal vibration MIL‐PRF‐28800F for a Class II instrument
  • Drop Protection                  1.2m (4’) drop onto hardwood or concrete flooring

Extech MA145 Battery Replacement

1. Remove the Phillips head screw at the lower back of the meter.

2. Open the battery compartment 3. Replace the two LR44 batteries observing correct polarity.

4. Re‐assemble the meter before use

5. Safety: Please dispose of batteries responsibly; never dispose of batteries in a fire, batteries may explode or leak; never mix battery types, install new batteries of the same type. 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.


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