Klein Tools ET310 Review: Stop Guessing Which Breaker Controls What

Every homeowner knows the scene: you need to replace a bathroom light fixture or install a smart thermostat. You walk down to the breaker panel in the basement, open the steel door, and find faded, scribbled pencil labels that say "Upstairs" or "Plugs". Finding the right breaker usually takes two people: one yelling from the bathroom and one flipping switches until the clock radios reset.

The Klein Tools ET310 solves this completely. You plug the transmitter into the outlet you want to de-energize, walk to the breaker box, and slide the handheld receiver down the rows of breakers.

How It Works: The 2-Pass Scanning Technique

The microprocessor inside the ET310 receiver learns the relative magnetic field strength of every circuit breaker in your electrical panel:

1. Pass 1 (Learning Scan): Run the receiver nose smoothly over each breaker switch from top to bottom. The tool records signal amplitudes across the panel.
2. Pass 2 (Target Acquisition): On the second pass, the receiver illuminates a bright green arrow and sounds a continuous tone only on the exact breaker feeding the transmitter.

Technical Specifications Comparison