Klein ET450 Advanced Circuit Tracer

Brendan Lamothe

Key Takeaways

  • The Klein Tools ET450T Circuit Tracer Kit helps locate and trace wires.
  • Accessories like the AC plug adapter and ground wire enhance functionality.
  • Adjustable sensitivity levels on the receiver ensure accurate signal detection.

Overview of the Klein Tools ET450T Circuit Tracer Kit

The Klein Tools ET450T Circuit Tracer Kit allows you to locate wires behind various materials and identify which circuit breaker controls the wire you're testing. This kit features a transmitter that you can plug into or hook up to any circuit and a receiver to trace the wire's path.

Kit Components and Accessories

Transmitter: Plug this device into a circuit, such as an AC outlet, using the provided AC plug adapter. The red lead is connected to the hot side, and the black lead to the common side.

Receiver: This device picks up the signal from the transmitter. It has adjustable sensitivity levels from 1 to 8, allowing you to choose an appropriate level without saturating the signal.

Using the Circuit Tracer

  1. Direct Ground Method: Plug the transmitter into the outlet, ensuring the larger prong goes to the neutral side.
  2. Connections:
    • Red lead: Attach to the hot side of the receptacle.
    • Black lead: Connect to the common side.


  • 3-foot red lead: Comes with a blade and alligator clip.
  • 20-foot ground wire: Used for the remote ground method. It attaches to the transmitter and the ground of another circuit.

Operation Details

The receiver can toggle its backlight, flashlight, and sound. Power is supplied by four AA batteries for the receiver and six AA batteries for the transmitter. While tracing wires, ensure the receiver and transmitter are kept at an appropriate distance to avoid interference.

Practical Application

When tracing a wire, adjust the receiver's sensitivity to pick up the transmitted signal. Move along the wire's path, noting the signal strength to determine the wire's location. The receiver should not register 99 constantly but should detect the signal clearly at varying strengths.

For example, tracing a wire from a receptacle to the ceiling showed readings fluctuating between levels like 72 and 26, helping pinpoint the wire's path behind drywall and studs.

This kit is priced at approximately $200. It offers reliable, practical solutions for tracing circuits within various structures.

Transmitter and Receiver Functionality

The Klein Circuit Tracer Kit ET450T features a transmitter that connects to any circuit in your house. Using the provided accessories, you can connect the transmitter to an AC plug or directly to your circuit breaker. The AC plug adapter is particularly useful for GFCI circuits.

When using the transmitter with the 20-foot ground wire, connect it to the ground of another circuit for optimal performance. Note that GFCI systems may trip when using this method. Instead, use the direct ground method for GFCI, ensuring the proper connection of the prongs and wiring.

The receiver in the kit is designed to detect the transmitted signals through various materials like drywall, cement block, and underground. You can adjust its sensitivity from levels one to eight to avoid signal saturation. Ensure the transmitter and receiver are not too close, as this causes interference.

Here’s a quick reference:

Button Press


Short Press

Turns backlight on/off

Short Press

Turns flashlight on/off

Long Press

Turns sound on/off

Both the transmitter and receiver are battery-operated, with the transmitter using six AA batteries and the receiver using four AA batteries. This kit allows you to trace wires accurately even in challenging conditions, ensuring reliable performance in different scenarios.

Demonstration of the AC Plug Adapter

Connecting the AC Plug Adapter

To connect the AC plug adapter, plug the red lead into the red side and the black lead into the common side. Then, insert it into an electrical outlet.

Ensure that the larger prong aligns with the neutral side of the receptacle. Connect the adapter to the transmitter with black to black and red to red.

Using the GFCI Circuit

When using the GFCI circuit, avoid using the 20-foot ground wire as it may trip the circuit. Instead, use the direct ground method.

Plug the adapter into the GFCI protected outlet. Connect it to the transmitter, making sure the larger prong fits the neutral side. This method prevents tripping and ensures proper operation when tracing circuits.

Accessories Description

Red Lead and Alligator Clips

The Klein ET450T circuit tracer kit includes a three-foot red lead. This lead comes with a blade, but you also have the option to attach an alligator clip. The red lead is designed to connect the red side of the receptacle to the hot wire. You can easily switch between the blade and alligator clip based on your requirement.

20 Foot Ground Wire

This kit also features a 20-foot ground wire. This is used to connect the transmitter to the ground of another circuit. It's specifically designed to provide stronger signal readings over a longer distance. Just keep in mind that it’s not suitable for use on GFCI systems, as it can trip the circuit. The ground wire works best with the direct ground method for optimal performance.

Understanding Grounding Methods

Remote Ground Method

This method uses a 20-foot ground wire connected to the transmitter. One end of the ground wire attaches to the transmitter, and the other end connects to the ground of another circuit. This setup provides stronger readings.

To perform the remote ground method:

  1. Connect the red lead to the red terminal and the blade to the hot side.
  2. Attach the ground wire to the transmitter.
  3. Plug the other end into a separate circuit.

Advantages include stronger signals, but it may trip GFCI systems, requiring a different approach.

Direct Ground Method

The direct ground method is essential when working with GFCI systems. Here, you only need to ensure the larger prong of the adapter goes into the neutral side of the receptacle.

Steps to follow:

  1. Plug the AC adapter into the wall.
  2. Connect the black lead to the black terminal and the red lead to the red terminal on the transmitter.

This setup is straightforward and avoids tripping GFCI systems, ensuring consistent signal detection.

Receiver Usage and Signal Detection

Adjusting Receiver Sensitivity

The receiver's sensitivity can be adjusted to detect signals from the transmitter on breakers, fuses, and wires through materials such as drywall, cement block, and underground. The sensitivity levels range from one to eight.

Sensitivity Level

Signal Strength





When using the receiver, ensure that the reading is not constantly at 99. Keeping the transmitter a reasonable distance from the receiver is crucial to avoid interference.

Key Functions

  • Power Button: Short press for backlight, long press for sound control.
  • Next Button Up: Short press for flashlight control.

Navigating Signal Interface

When navigating the signal interface, monitor the receiver's reading:

  • Levels close to 99 indicate proximity to the transmitter.
  • Lower numbers suggest moving away from the signal source.

Here’s an example of how to trace a wire:

  1. Start at the receptacle with the transmitter plugged in.
  2. Move the receiver away and watch the readings fluctuate.
  3. Higher readings indicate closeness to the wire's path.


Signal Reading

Close to window


Near ceiling


Farther from wire


Following these steps helps ensure accurate detection, even when wires are behind walls or under flooring.

Wire Tracing Demonstration

Locating the Receptacle

To start the process, ensure the transmitter is plugged into the receptacle you want to trace. Make sure black to black and red to red connections are secure. The receiver can then be used to detect the signal from the transmitter. Hold the receiver close to the transmitter, noting that the signal will be strongest when nearby.

Short press the power button to activate the backlight or long press to toggle sound. Adjust the sensitivity to avoid saturation, keeping readings balanced for accurate tracing.

Wire Path Identification

Move the receiver along potential paths of the wire. The signal strength should fluctuate as you trace its route behind walls or under floors. If you receive a strong signal closer to windows or studs, this indicates where the wire may be running.

Regularly check the strength, ranging from level one to eight, to ensure the signal is neither too weak nor overwhelmed. By identifying critical spots with changes in signal, pinpoint the wire's path accurately from the receptacle to its endpoint.

Product Pricing and Availability

The Klein Circuit Tracer Kit ET450 is currently available for approximately $200. This kit includes various accessories that assist in identifying circuit breakers that control different circuits in your home. Key components include:

  • Transmitter and Receiver: Essential for tracing wires behind walls, drywall, underground, and through concrete.
  • AC Plug Adapter: Useful for GFCI circuits.
  • 3-Foot Red Lead with Blade: Interchangeable with an alligator clip.
  • 20-Foot Ground Wire: Provides increased reading strength but isn't compatible with GFCI systems.

The transmitter requires six AA batteries, while the receiver needs four AA batteries. Overall, this toolset offers reliable functionality for various electrical tracing needs in residential settings.


Using the Klein ET450T Circuit Tracer Kit can simplify finding electrical circuits in various situations. Key features include:

  • Transmitter: Can be plugged in or hooked up to any circuit in your home.

    • AC Plug Adapter
    • 20-foot Ground Wire
    • Three-foot Red Lead
    • Alligator Clips
  • Receiver: Detects the transmitted signal on breakers, fuses, and wires, even through plaster and drywall.

    • Adjustable sensitivity (Levels 1-8)
    • Built-in backlight and flashlight
    • Sound settings

Operational Tips:

  • Keep the receiver and transmitter at a distance to avoid interference.
  • For GFCI systems, use the Direct Ground Method.
  • The correct configuration helps in consistently tracing the wiring accurately.

The current price for this versatile kit is around $200. This investment is worthwhile for those who need a reliable tool for tracing electrical circuits.