Klein Tools ET310 AC Circuit Breaker Finder with Integrated GFCI Outlet Tester The Klein Tools ET310 Circuit Breaker Finder with Integrated GFCI Outlet Tester is a digital circuit breaker finder used to locate the correct circuit breaker in a panel to which an electrical outlet or fixture is connected. The Transmitter is connected to the electrical outlet or fixture in the circuit while the receiver is used to scan the breakers in the circuit panel. The Transmitter also features a GFCI outlet tester. Circuit Breaker Finder locates the correct breaker in a panel. Tester consists of two parts: a Transmitter and a Receiver. GFCI Outlet Tester integrated in receiver. Transmitter docks in the Receiver for convenient storage as a single item when tester is not is use. Transmitter incorporates a three-pin plug for connecting to North-American-style grounded electrical outlets. The transmitter may be connected to other electrical fixtures using optional accessories which are sold separately (Cat. No. 69411). Receiver powers off automatically after approximately three minutes of non-use to conserve battery life. Transmitter is powered by the circuit when connected to the electrical outlet or fixture. Low battery indicator. Easily accessible battery compartment. Uses one 9V battery in receiver only; Transmitter does not require a battery. Built to withstand a 6.6-Foot (2 m) drop. CAT II 120V safety rating. Measurement Category II is applicable to test and measuring circuits connected directly to utilization points (socket outlets and similar points) of the low-voltage MAINS installation. Includes Transmitter, Receiver, user manual, and 9V battery (for Receiver). For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isn’t just the name of our company, it’s also our family name. And since we’re an American company that’s family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn’t just make great products, we make great products that stand up to the demands of the professionals who use them every day … Since 1857. AC Circuit Breaker Finder with Integrated GFCI Outlet TesterThe Klein Tools ET310 Circuit Breaker Finder with Integrated GFCI Outlet Tester is a digital circuit breaker finder used to locate the correct circuit breaker in a panel to which an electrical outlet or fixture is connected. The Transmitter is connected to the electrical outlet or fixture in the circuit while the receiver is used to scan the breakers in the circuit panel. The Transmitter also features a GFCI outlet tester. Features:- This circuit breaker finder can quickly and accurately locate the correct circuit breaker in a panel corresponding to the circuit to which an electrical outlet or fixture is connected- Tester consists of two parts: a Transmitter, connected to the electrical outlet or fixture and a Receiver, used to scan the panel to locate the correct breaker- Receiver delivers clear visual and audible indications when the correct breaker has been located- Operates on 90-120V AC circuits- Transmitter incorporates a GFCI outlet tester to inspect the wiring condition at the electrical outlet and test GFCI devices Customer Comments:1. Wish I had one of these 50 years ago. Finding the correct breaker used to be a slow trial and error time consuming method. This is really fast. As other reviewers noted other breakers may give a weak false positive but the correct breaker gives a very strong positive. A very handy tool for anyone working on electrical circuits in a house. 2. I spent some time reading reviews and watching videos on circuit breaker finders. I noticed the videos of this one seemed to work better than others I saw. In particular, I was considering one that had an adjustable sensitivity thinking that it would help when the device struggled between two breakers. I ended up with this one because of the description on how it’s calibrated. It turns out that this calibration feature works very well to select the correct breaker. It’s not 100% due to how close together two circuits run. It will trigger on two or in between two breakers. This happened for me only twice on two adjacent breakers. I found that by resetting and re-calibrating the unit on only the two triggering breakers and one on either side of them, it improved the selection of the correct breaker. I mapped out my electrical panel with 34 breakers in about 5 hours. I’m very happy with the purchase.