Cable location using the T1 transmitter

Follow Avatar Anthony Caplin
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The T1 transmitter is used to actively apply a locate signal to cables or metallic pipes. This signal can be traced using the locator in Active Line mode (L).

Use of the T1 is strongly recommended, as passive power or radio signals may not be present, or detectable, on all cables and pipes.


Induction Mode

The T1 has an internal aerial that will induce a signal onto a line (or lines) directly below it. This is useful when you do not have direct access to the line. Generally, induction is only effective to depths of 2m (6’6”).

NOTE: that the induction mode is indiscriminate and will apply a signal to all conductors within its range.

Induction is only available with frequencies 8kHz and above.


Place the transmitter over the approximate position of the underground utility with arrows pointing parallel to its path. Set the locator’s sensitivity to 100% and start locating the line at least 10m (33 feet) away from the transmitter. Mark the ground when the locator detects any signal spike.


NOTE: Induction cannot apply a signal to a line below reinforced concrete. 

NOTE: The locator may detect the transmitter signal directly from the T1 rather than the target line, so do not attempt depth measurements within 10 meters of the transmitter.

To check if you are detecting a signal from the T1, point the locator directly at the transmitter. If the locator’s signal strength increases, either reduce the transmitter power or increase the distance between you and the transmitter. If the signal strength decreases, the signal is from the buried line.

Direct Connection

Connection to a power cable sheath should only be undertaken by qualified personnel.

Direct Connection is an effective way to apply the T1 locate signal to a specific cable or pipe network so that it can be traced from above ground. Connections can be made to any metallic part of the pipe or cable such as valves, meters, junction boxes, street lights, pipeline markers or other access points.


With the T1 switched off, plug the Direct Connect lead into the accessory socket. Attach the red lead to the pipe or cable (if necessary, clean the connection point to ensure a good electrical contact). If the jaws of the clip do not open far enough, and if the connection point is a suitable material, use the supplied magnet.

Connect the black lead to the earth stake which should be secured in the ground 3 – 4m away from, and at right angles to the target line.

Alternatively the black lead may be clipped to a valve box, manhole cover or another earthed point. Use the earth spool lead to extend the earth connection if necessary.

Switch the T1 on. A good connection is indicated by a drop in loudspeaker tone. If there is no tone replace the batteries.

Start with the T1’s lowest power setting. A pulsed loudspeaker tone indicates a good connection. If there is no tonal change, check the electrical contacts and the ground. If necessary, change the position of the ground stake or pour water over the ground contact if placed in dry soil or sand. If there is still no change in tone increase the power setting.

Note: The locator can detect a signal many times weaker than what is necessary for a T1 tone change and short distances can be traced without a pulsed tone from the loudspeaker.

To remove the direct connection cable grip the black sleeve on the outside of the plug and ease off the connector.

 Do not pull the wire as this may damage the cable and/or socket.

Regularly check your locator and T1, in all modes over a cable which provides a response that you are familiar with.

Signal Clamp (optional extra)

The optional Signal Clamps can be used to apply a T1 locate signal safely to a cable or pipe up to 215mm (8.5”) in diameter without interrupting the supply. Signal clamps are not suitable for connecting around lamp posts.


With the T1 switched off, plug the Clamp lead into the accessory socket. Place the Clamp around the pipe or cable ensuring the jaws are completely closed.

Switch the T1 on, then open and close the Clamp. If the jaws are closing correctly there will be a change in tone as the jaws are closed.

An earth connection from the T1 is not necessary but optimal signal transfer is only generally achieved if the target line is grounded at both ends. This is usually the case with power cables.

To avoid the risk of electric shock, the signal clamp must be connected to the transmitter before being placed around the pipe or cable.