Klein ET310 Circuit Breaker Finder with GFCI Outlet Tester

Klein Circuit Breaker Finder with GFCI Outlet Tester

The Klein ET310 Circuit Breaker Finder with GFCI Outlet Tester conveniently combines two critical diagnostic tools into one. I’m using it while adding outlets and fixtures in a retail store. Combine it with the new Klein Tools Voltage Tester ET45 and you’ve got a powerful circuit tracing and testing duo.


  • Easy-to-use and accurate locator
  • Transmitter doubles as a GFCI outlet tester
  • Transmitter plugs into the end of the receiver when not in use
  • 3-minute auto power-off to preserve included 9-volt battery


  • Occasional ghost voltages; not a deal-breaker


Klein’s very helpful tool combination plugs together to help you keep either piece out of the lost and found. Location is quick and accurate, but every so often you’ll experience a ghost, which just takes the flip of a breaker to verify. Having the outlet tester along with the tracer covers a great deal of verification and diagnostic work I need to do, saving me time and making my work easier.

Klein ET310 Circuit Breaker Finder Performance

Up Electricity Creek

Going to a job without a tool like the Klein Tools circuit breaker finder with GFCI outlet tester is a lot like being up a creek without a paddle, as the old saying goes. If you don’t want the diagnosis to take longer than the cure, it sure helps to have it. Klein’s combo of these two devices isn’t a first of its kind, but it’s also a little unusual (in a good way).

Operating the Klein ET310 breaker finder is simple. You plug the Transmitter into the outlet in question and head to the panel with the Receiver to find the circuit. When the Receiver is on (powered by an included 9-volt battery), the tip illuminates in green. When the Receiver locates the correct circuit, a red light illuminates and an audible indicator sounds.

Klein Tools ET310 GFCI Outlet Tester

The Receiver mimics an outlet so you can plug in and store the transmitter after use. It keeps the pair together so you’ll (hopefully) avoid losing one or the other. The PTR guys claim I lose a lot of tools, so…challenge accepted!

Klein GFCI Outlet Tester Circuit Tracer

The Ghost of Circuits Past

The Klein circuit breaker finder Receiver occasionally flashed red and sounded on what turned out to be a ghost voltage. It wasn’t a big problem and just takes the flip of the breaker to verify. Seasoned Pros understand false positives, but it could trip up some DIYers.

Klein Tools Circuit Breaker Finder ET310

To test a GFCI circuit, simply press the Transmitter’s gray button to simulate a trip. If it fails, a replacement is in order. The Transmitter also has the familiar legend of correct and incorrect wiring which corresponds to various combinations of its three LEDs.

Klein built the circuit breaker finder to withstand a 6.6-foot drop. The tool also carries a CAT II 120V rating and has a 3-minute auto power-off timer to conserve the onboard battery.

Klein ET310 Circuit Breaker Finder Price

The Klein circuit breaker finder with GFCI outlet tester (ET310) comes in at around $50. Here’s a look at the field of competition:

The Bottom Line

The Klein circuit breaker finder with GFCI tester combines two critical diagnostic tools in a tough package at a good price. Designing the two components to plug together was a smart idea. We also like the auto power-off feature to conserve the 9V battery. It’s a helpful electrical installation tool combo that serves the Pro as well as the serious DIYer. This tool makes for a great addition to anyone’s tool bag.

Klein Circuit Breaker Finder with GFCI Outlet Tester Specifications

  • Item Number: ET310
  • Special Features: Transmitter docks in Receiver; Integrated GFCI outlet tester
  • Dimensions (LxHxW docked): 10.96 x 2.16 x 1.39 in.
  • Material: PC & PC-ABS housing and electronic components
  • Standard: CAT II 120V
  • Included: Transmitter, Receiver, user manual, and 9V battery
  • Weight: 7.2 oz. (204 g)
  • Price: $49.97

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