Klein Tools ET450 Advanced Circuit Tracer Kit vs Fluke BK120 SmartTrace Breaker Finder

The ET450 is the only tool in this group that gives you a number to compare between two candidate breakers, and the only one that will trace a circuit with the power off. The BK120 does the plug-in job for far less bulk and is the rare finder whose maker prints the adjacent-breaker procedure in the manual instead of pretending the problem does not exist.

Klein Tools ET450 Advanced Circuit Tracer Kit

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The one here that replaces a beep with a number, and the only one that will follow a circuit you have already switched off.

• The receiver shows signal strength as 0 to 99 on the LCD plus a ten segment bar, so two candidate breakers become two numbers rather than two beeps.
• Eight sensitivity levels, and Klein tells you which to use: 1 to 3 for energised circuits and 4 to 8 for de-energised ones, where the signal is weaker.
• Traces energised or de-energised breakers, fuses and wires, with the receiver also carrying an 80 to 1000 V AC non-contact function and a 6 lumen light.

• Klein's preferred remote ground connection will trip GFCI receptacles, and the manual lists the workarounds rather than fixing it.
• The direct ground connection avoids that but Klein notes wires are less traceable that way because parallel conductors cancel each other out.
• Tracing depth is specified at 0 to 1.64 ft (0.5 m) depending on the medium, so it is not a deep underground locator.

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Fluke BK120 SmartTrace Breaker Finder

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The plug-in finder whose maker actually writes down what to do when the receiver picks two breakers instead of one.

• The user guide states that if the finder detects two adjacent breakers on the second scan you reset it, turn it 180 degrees and rescan, which is a published answer to the failure that defines this category.
• Fluke also tells you to confirm the result by tripping the breaker and checking that the transmitter in the socket has gone dark, which is the only free verification there is.
• Both halves are rated CAT III 150 V and IP40, with the transmitter carrying UL 1436 and CSA C22.2 No. 160, and the receiver adds a 90 to 240 V AC non-contact mode with dual sensitivity.

• The transmitter is line powered at 110 to 125 V AC, so there is no way to trace anything that is not energised.
• The breaker indication is a green light and a beep with no signal strength number, so a tie is resolved by rotating the tool rather than by reading two values.
• Fluke notes an inaccurate reading may occur if the tip is placed at any angle other than flat on the breaker face.

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Side by side

The bottom line

Our overall pick is the Klein Tools ET450 Advanced Circuit Tracer Kit - The one here that replaces a beep with a number, and the only one that will follow a circuit you have already switched off. Choose the Fluke BK120 SmartTrace Breaker Finder instead if the homeowner or service tech who wants one pocket tool for panel mapping and wants the maker's own procedure for the ambiguous case.

Want the full picture, including the other options we compared and the popular one we'd skip? Read the complete The Best Circuit Breaker Finders: 4 Compared (and One to Skip).