Cable Tracers

Cable tracers are used for tracking and troubleshooting cables quickly. They are suitable for identification and maintenance of telephony networks and also for testing any kind of lines not-connected to the mains. Suitable applications are wiring test for computer Local Area Networks (LAN) and telephony extensions.

There are countless cable tracers on the market, but they all operate on similiar principles. They transmit a signal on to the cable and have a receiver that detects that signal.

Method: use the tone generator and the probe to determine where a cable is going and whether or not (and where) the cable is interrupted.

The Tone Generator is a hand held, battery powered instrument designed to perform a variety of tests on unenergized telephone lines or LAN cables. Alligator clips and a standard RJ11 plug allow the tone generator to be connected to stripped wires, terminal panels, wall plates, or modular single line jacks. The Tone Generator usually generates continuous tone or warbled tone with selectable test frequencies. Frequencies are usually around 1kHz frequency.

Here is a video that shows how to use Tone and Probe Cable Tracer.

The Line Tracer is a hand held inductive tracer that will help to identify wires without piercing the insulation. It can trace Tone Generator signals through dry wall, wood and many other non metal surfaces.

The conventional use of the inductive amplifier is the location of breaks in hidden wires, even buried in concrete. The typical wire detection range in a concrete wall is 10-20 cm. One of the manufacturers of the inductive amplifier is Tempo. Inductive amplifiers can also be used to find an individual cable pair in a telephone cross connect or cable head when used in conjunction with a tone generator.

Inductive amplifier can be used to trace mains wiring inside the wall. In case the mains wiring is is or can be reliably disconnected from mains power source, it is possible to trace disconnected mains wiring like telephone wiring is traced. Make sure the power is off before connecting the tone generator. If live mains wiring needs to be tested, you need tools specific for that: Voltage detectors are helpful once you find your wires — they let you test whether the wires are live. You can also buy circuit and wire tracers made specifically for the purpose of locating electrical wiring behind walls and underground. These tools tend to be expensive, though.

Some instructional articles:

How to Use a Wire Tracer article gives you some basic instructions.

Deciphering wiring article has some tips on cable tracing and notes cases where tracers do not always work well.

How to find an open circuit or shorted wire the FAST easy way

Are you interested in circuit diagrams of cable tracers? Here are some pointers to those:

My Cable tracing inductive amplifier blog posting  has several circuit diagrams.

Fox and Hound cable tracer article has links to generator circuits.

Fox – Hound, Cable Tracers, Signal Tracers, Line Tracers – whatever you want to call them project page has circuit diagrams.

Cable wizard cable tracer manual has many circuit details in it.



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  2. Tomi Engdahl says:

    Knowing What’s Below: Buried Utility Location

    We humans have put an awful lot of effort into our infrastructure for the last few centuries, and even more effort into burying most of it. And with good reason — not only are above ground cables and pipes unsightly, they’re also vulnerable to damage from exposure to the elements. Some utilities, like natural gas and sanitary sewer lines, are also dangerous, or at least perceived to be so, and so end up buried. Out of sight, out of mind.

    Call Before You Dig

    By law, every public utility company in the United States must participate in a “one-call locator service.”
    Location services are paid for by the utility companies, so there’s no direct charge to the customer.

    Anyone doing any sort of excavation is required to call (or now, submit a request online) to schedule a location service to mark the intended work area. This applies to any digging
    If you’re going more than 15″ deep, you need to call, because if you cause any damage to underground services, you’re on the hook for it. If you live, of course.

    Beep, Beep, Beep

    Once a ticket is entered, a location technician will usually come mark the job site within a couple of days.

    Location techs have a wide range of tools to locate that which can’t be seen. Given that most underground facilities have some kind of metallic component — older water and sewer lines, natural gas pipes, and the copper wire in electrical or telecom cables — electromagnetic tools get the bulk of the work done.

    Detectors can be active or passive. Passive methods are usually used to locate facilities that already have an AC signal on them, like power lines or telecom cables.

    Active detection applies a current to an above-ground section of a utility line, like a water or gas meter. An AC signal is applied to the line by the transmitter, which turns it into an antenna. Utility companies sometimes even lay copper wire alongside plastic lines as an aid to active detection.
    Handheld receivers with highly directional antennas are swept over the ground to pick up the signal

  3. Tomi Engdahl says:

    MASTECH MS6818 Located underground concrete pipe at 1.4 meter depth

    Using the “MASTECH MS6818″, I located underground concrete pipe at 1.4 meter depth and at 20 meters of length. I used a wire with an copper area of 0.7mm^2 and a plastic isolation. (1.1 meter is only the entry depth, the pipe is actually located at 1.4 meter)

  4. Tomi Engdahl says:

    Tracing out Live Network Cables

    This clever trick helps you identify un-marked network outlets. A Toner and Tone-probel will not work when a network jack is connected to a live switch port in the server room (switch room). By using a simple batch file running on a laptop, you can create a beaconing effect using the swithes link lights.

  5. Tomi Engdahl says:

    How-To: Trace Live Ethernet Cables to a Switch

    Interrupting live networks is painful. But sometimes you’ve got to do work in the cable closets, server rooms, and other crowded and complex rivers of wire that are your responsibility. Does there have to be an acceptable amount of downtime for tracing and testing wires? There are a few low-impact methods for locating cable ends which are popular but disruptive. There is one newer strategy, though, which can lead you right to the cable end you seek without network disruption or disconnection. Check out the article here:

  6. Tomi Engdahl says:

    How to find an open circuit or shorted wire the FAST easy way

  7. Tomi Engdahl says:

    Harbor Freight – Cen-Tech Cable Tracker (Item#94181)

    Pass or Fail? Harbor Freight Cable Finder #94181

  8. Tomi Engdahl says:

    How to use a tone generator and probe to locate cables

    In this video we demonstrate the use of a tone generator and an inductive amplifier (probe) to locate cables.

    How to trace and track wires using a cable tracker

    Hi, this ‘how to’ video shows how to use a cable tracker tone and probe to trace and track various cables and wires.

  9. Tomi Engdahl says:

    Interesting looking commercial cable location device, product page has some cable tracing usage instructions:

    ESAMACT MS6818 Advanced Wire Tester Tracker, Multi-function Cable Detector

    working principle:

    The MS6818 cable detector includes a transmitter and a receiver. The transmitter supplies a modulated AC voltage to the corresponding cable. The AC voltage creates an electric field around the cable. The receiver is fitted with a coil. If the receiver is placed close to the corresponding electrical conductor, the flux line will Pass through the coil and into the receiver. This phenomenon is also known as a penetrating coil. A small voltage is generated in the coil, and the receiver’s electronic circuitry calculates this voltage and displays it on the display. The MS6818 is special in that the transmitted signal is digitally encoded. This ensures that the signal is clearly received by the receiver, avoiding the erroneous display caused by any interference fields such as electronic fluorescent ballasts or frequency converters.

    Application areas:

    This instrument is widely used in communication cable construction, power cable construction, construction pipeline construction, communication cable to power supply circuit and electric heating line maintenance work, is an indispensable tool for frontline construction maintenance personnel.

    Detect the laying path of cables, electrical lines, and water supply pipes buried in walls and underground.

    Detect cables that are buried in walls and underground, and open and short circuits in electrical circuits.

    Look for fuses and their fuses.

    Look for covered sockets and junction boxes.

    Look for open and short circuit faults in the electric heating circuit under the floor.

  10. Tomi Engdahl says:

    What To Do if You Mislabel a Cable in a MDU Application (The RPT-AAA)

  11. Tomi Engdahl says:

    Cable Tracker || DIY or Buy || A useful tool for every electrician!

    In this episode of DIY or Buy we will be having a closer look at a cable tracker. It is a tool that is used to locate wires in you wall. This is helpful to drill holes in your wall or to locate a fault in your wiring. I will show you how the sender and receiver functions and afterwards I will create a super crude, but functional DIY version in order to find out whether we should Buy the product or create our own DIY version. Let’s get started!

  12. Tomi Engdahl says:

    MY6818 cable tracer wire locator tracing an underground telephone wire

  13. Darrol says:

    I have to dispute that these non-contact testers work on induction. Induction would require current to flow, and I just used a Southwire tester on wires that are not conneted on either end, so there’s no current flowing. I believe the receivers are sensitive to the AC voltage field, and simply have a very high impedance amplifier. One company says they have a FET and an IC ampllifier, so that sounds right. No-one is talking about a Hall Effect sensor, which is what is used in automotive testers because the masses of metal all over the place would prevent an electrostatic tester from working. And, the automotive testers are very well known, and various literature says they work on inductively sensing a fairly strong current generated by a separate transmitter. My furstruation is the ALL the commercial electrical testers (i.e. non-automotive) output a variable strength audio signal and after 15 minutes, my ears are work out. Someone ought to make a receiver where the pitch of the sound tells you how close you are to the wire. That’s called a VCO, and it would be a super-cheap add-on.

    • Tomi Engdahl says:

      You are right that name inductive detector or inductive tracer are misleading in most cases.

      You are also right that
      “the receivers are sensitive to the AC voltage field, and simply have a very high impedance amplifier.”

      I have even built some circuits like that

      AC induction is an electromagnetic phenomenon where a changing magnetic field—often from power flow through nearby power lines—can cause an induced current and voltage to be present on conductors that are nearby and not actually connected to any power supply. The strength of the induced current and voltage depends on factors such as the power source distance and current.

      Term “induced voltage” can sometimes used to describe voltages caused by both inductive and capacitive coupling between wires
      AC electricity causes induction because of the constantly changing character of its magnetic field, as voltage changes repeatedly between positive and negative.

  14. Tomi Engdahl says:

    Trace ESD current paths with the HP 547A

    In the mid-1970s, HP developed a set of three handheld probes; a logic probe (HP 545A), a current pulser (HP 546A), and a current tracer (HP 547A). These were replaced later with the updated HP10525T logic probe and 10526T pulser sold together as the HP 5015T Logic Troubleshooting Kit. As far as I know, the current tracer was not upgraded. The combination of current pulser and current tracer were originally meant to locate shorts or latch-ups in CMOS and HCMOS circuits, circuit board shorts, and so forth.

    The original user manual says:

    The HP 547A Current Tracer is a hand-held probe which enables the precise localization of low impedance faults in electrical systems. The probe senses the magnetic field generated by a pulsing current internal to the circuit or by current pulses supplied by an external stimulus such as the HP 546A or 10526T Logic Pulsers. Indication of the presence of current pulses is provided by lighting the indicator lamp near the Current Tracer tip. Adjustment of probe sensitivity over a 1 mA to 1A range is provided by the SENSITIVITY control near the indicator.

    It occurred to me recently that the current tracer might help map out the path of ESD discharge currents, especially for complex systems with multiple circuit boards, power supplies, and cables.

    We were easily able to isolate the path of ESD to just a few of the cables as well as the display board. The lamp brightness indicated the relative amplitude (and dominant path) of injected ESD current pulse.

    Current-tracer probes were more prevalent 10 years ago, but occasionally I see them pop up on eBay or other surplus outfits for $50 to $100. This just might be the right tool for those really difficult ESD challenges and I plan to keep this in my troubleshooting kit.

  15. Harvey Self says:

    I appreciate how this article was written with full of impressive words. I have learned more information after reading this. Big thanks for sharing this informative article.

  16. Tomi Engdahl says:

    If anyone wants to know more about utility locating, which is what those wires are for, this Youtube channel is pretty good. One of his videos may even show using those wires to connect the tracer:


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