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Tool Type
Signal Detector
Voltage Detector
Battery Operated
LCD Display
Ease of Installation
Beginner (Installs < 10 minutes)
Extech Instruments
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Measures Watts, Current and Voltage with AC/DC True Power Measurements to 240kW
Extech Instruments 380940 400A True RMS AC/DC Watt Clamp-On
Extech Instruments 380940 400A True RMS AC/DC Watt Clamp-On
Extech Instruments 380940 400A True RMS AC/DC Watt Clamp-On
Item# 90240
Price: Normally $339.99 
Hot Deal $309.96
Free shipping on orders over $50 - See Details


  • True RMS AC Voltage and Current
  • 0.9" (23mm) jaw opening
  • Large 4000 count LCD display
  • Fast 40 segment analog bargraph

Essential Info

The Extech Instruments 380940 400A True RMS AC/DC Watt Clamp-On measures watts, current and voltage with AC/DC True Power measurements to 240kW. It features true RMS AC voltage and current measurements and displays in a large 4000 count LCD with 40 segment analog bar graph. It has a 0.9 (23mm) jaw opening allowing it to clamp onto anything you want tested for its AC power load. With careful use, this meter will provide years of reliable service.


What's Included

  • Test Leads
  • 2 AA Batteries
  • Carrying Case
  • More Info

    Additional Features
  • Data Hold, Max/Min recall, Auto Zero (DC current), plus low battery indication
  • Frequency to 10kHz
  • Auto power off
  • Specifications

  • Display: 3-3/4 digit (4000 count) LCD with 40 segment bar graph
  • Functions: Watts, ACA, DCA, ACV, DCV, Frequency
  • Polarity: "-" indicates negative polarity; positive assumed
  • Current Sensor: Hall effect sensor type
  • Overload Indication: Left blinking digit
  • DCA Zero Adjust: One touch zero key
  • Display Rate: 2 readings/second (20 readings/second for bar graph)
  • Auto Power Off: Meter turns off automatically after 30 minutes
  • Battery: Two 1.5V AA batteries
  • Operating Temp.: 40F to 1220F (-100C to 500C)
  • Operating Humidity: < 85% RH
  • Power Consumption: Approximately 10mA DC
  • Weight: 6.7 oz. (190g) including battery
  • Dimensions: 7.2 x 2.5 x 1.4" (183 x 63.6 x 35.6mm) (HWD)
  • Jaw Opening: 0.9" (23mm) maximum conductor size
  • Standards: IEC 1010 Category III 300V, Category II 600V
  • Important notes:
    Only defective exchanges for identical item within 30 days of purchase. No other returns allowed on this item. For defective returns after 30 days, please contact the manufacturer.
    Manufacturer contact information: Extech Instruments Corp, Tel: (781) 890-7440 Ext 200


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