Klein Tools RT390 Circuit Analyzer

Klein Tools RT390 Circuit Analyzer tests the wiring conditions at an electrical outlet and displays various readings on a large LCD screen. This analyzer displays AC line voltage, inspects GFCI and AFCI devices with time to trip device, and performs voltage drop tests at 12A, 15A, and 20A current loads. When monitoring, the background will turn red if the voltage drop is greater than 5%. Various buttons on the RT390 analyzer include a load button that tests 12A, 15A, and 20A to display percentage drops, a power/reset button, and an energized indicator that is bright red to show voltage. Klein Tools RT390 Circuit Analyzer has a detachable cord and comes in a pouch with 3x AAA alkaline batteries.


  • Large color LCD
  • Detects and identifies common wiring faults in standard, AFCI, and GFCI electrical outlets
  • Detects dual (open neutral/open ground) wiring faults
  • Inspects AFCI and GFCI devices, including trip time and trip current
  • 12A, 15A, and 20A load testing to measure percentage voltage drops
  • Powers off automatically after 5 minutes of inactivity to conserve battery life
  • Detachable cord for easy storage


  • Detectable Wiring Faults
    • Correctly wired
    • Open ground
    • Open neutral
    • Open hot
    • Dual open
    • Reversed hot/ground
    • Reversed hot/natural
  • For use with North American 120VAC 3-wire electrical outlets
  • CAT III 135V safety rating
  • 10.92oz weight
Published: 2023-02-17 | Updated: 2023-02-27