The Klein ET310 Breaker Finder with GFCI Outlet Tester conveniently combines two key diagnostic tools into one. I use it when adding outlets and fixtures in retail stores. Combine it with the new Klein Tools Voltage Tester ET45 and you have a powerful circuit trace and test combination.
advantage
- Easy-to-use and accurate locator
- Transmitter doubles as GFCI receptacle tester
- The transmitter plugs into the end of the receiver when not in use
- 3-minute automatic shutdown to conserve the included 9-volt battery
shortcoming
- Occasional ghost voltages; not a deal breaker
recommend
Klein's very useful set of tools plug together to help you put any item in the lost and found. Locating is quick and accurate, but every once in a while you'll come across a ghost, just flicking the circuit breaker to verify. Using a socket tester with a tracer does a lot of the verification and diagnostics I need to do, saving me time and making my job a lot easier.
Up Power Creek
Going to work without tools like the Klein Tools Circuit Breaker Finder and GFCI Outlet Tester is like swimming up a creek without a paddle, as the saying goes. If you don't want a diagnosis to take longer than a cure, then accepting it will definitely help. Klein's combination of the two devices isn't the first of its kind, but it's also a little unusual (in a good way).
Operating the Klein ET310 Circuit Breaker Detector is simple. You plug the transmitter into the outlet in question, then go to the panel with the receiver to find the circuit. The tip glows green when the receiver is on (powered by the included 9-volt battery). When the receiver finds the correct circuit, a red light will come on and an audible indicator will sound.

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

circuit ghosts of the past
The Klein Breaker Detector Receiver occasionally flashes red and sounds, which turns out to be phantom voltage. It's not a huge problem, just flip the breaker to verify. Seasoned professionals understand false positives, but it can mislead some DIYers.

To test a GFCI circuit, simply press the transmitter's gray button to simulate a trip. If it fails, replace it in sequence. The transmitter also has the familiar right and wrong wiring legends, corresponding to various combinations of its three LEDs.
Klein makes circuit breaker detectors that can withstand a 6.6-foot drop. The tool is also CAT II 120V rated and has a 3 minute auto off timer to save onboard battery.
Klein ET310 Circuit Breaker Finder Price
A Klein Breaker Detector with GFCI Outlet Tester (ET310) sells for about $50. Here's a look at the field of play:
- ExTech CB10: $39.99
- Southern Wire Tools 41210S: $38.99
- Klein Tools ET310: $49.97
- Ideal 61-534: $124.99
the bottom line
The Klein Breaker Finder with GFCI Tester combines two key diagnostic tools in one rugged package at an affordable price. It's a smart idea to design the two components to plug together. We also like the auto power off feature to save the 9V battery. Here's a useful bundle of electrical installation tools for both the professional and the serious DIYer. This tool makes a great addition to anyone's toolkit.
Klein Breaker Finder with GFCI Outlet Tester Specs
- Product number: ET310
- Special features: Transmitter docks in receiver; integrated GFCI receptacle tester
- Dimensions (L x H x W butt): 10.96 x 2.16 x 1.39 inches
- Material: PC & PC-ABS housing and electronic components
- Standard: CAT II 120V
- Includes: Transmitter, Receiver, User Manual and 9V Battery
- Weight: 7.2 oz. (204 g)
- Price: $49.97