3M CablePipe Locating Techniques Manual

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Section 3  Power Cable Locating Techniques
1. Introduction
1.1 Read Section One of this manual to learn more general information about each of the following
signal application methods. The following paragraphs provide specific instruction on applying
signal for power cable locating.
Danger! Voltage greater than 240 volts will damage equipment and cause personal injury and death.  Make all
direct test connections before turning on the Transmitter.   Then activate the Transmitter in the Ohms
mode and...

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3. Applying Signal to Power Cables: Induction Method
3.1 The Induction method broadcasts signal into an area.  No access to the cable is necessary.  Use
this only when there are no other buried conductors present, or when locating all conductive
buried services in a general area.  Perform the following procedures to use the Induction method.
3.2 Place the Transmitter on the ground over the cable to be located. The Transmitter hinge should be
in line with the cable path, as shown above.  Be certain...

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4. Applying Signal to Power Cables: Dyna-Coupler Method
Warning: A potential for electrical shock exists when using the Dyna-Coupler on energized cables.   Use
appropriate safety procedures. DO NOT USE ON CABLES CARRYING IN EXCESS OF 600 VOLTS RMS.
A. Applying Signal to Primary Cables
4.1 Use the Dyna-Coupler method to put tracing signal on the neutral of either primary or secondary
cables and energized cables. The neutral and its grounds form a circuit path for the signal to
follow. When you apply...

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B. Applying Signal to Secondary Cables
4.5 To locate secondary cables, the easiest access to
the neutral is at the meter box.  There are several
ways to put signal on the neutral.  If the riser pipe
is nonmetallic (usually PVC), clamp the Dyna-
Coupler around the pipe as shown.  The jaws of
the coupler must fully close for signal
transmission.  This may be impossible if the riser
is flush with the mounting structure.
4.6 If the riser is flush with the mounting structure, it
may be impossible to clamp...

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5. Identifying Slack Loops
5.1 To identify the presence of a slack loop in the cable path, first locate and mark the cable path.
Then find the maximum response over the marked cable path and press the gain adjust key.
5.2 Retrace the cable path with the Receiver held so the handle is perpendicular to (across) the cable
path, as shown. When the Receiver passes over a slack loop, the signal increases and the bar graph
closes. Mark each response.
6. Identifying A Cable Open End
6.1 It is sometimes...

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7. Identifying Primary Power Cables
7.1 This procedure uses the Receiver and a Dyna-Coupler to identify a particular primary cable in a
group of similar cables.  This operation is sometimes called phasing.  The Transmitter is used to
apply tone to the target cable using the direct-connect method.
7.2 Follow standard procedures and remove the source elbows and park them at ground.  Remove the
load elbows and park at ground. After all phases have been de-energized and discharged, at the
load end, remove...

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8. Locating Open Concentric Neutrals
8.1 Open primary concentric neutral conductors will cause the normal neutral current to seek a path
around the open.  This path is usually through the adjacent earth and will cause a voltage gradient
around the open.  The 60 Hz voltage can be detected at the surface using the earth contact frame.
If you are confident that an open concentric neutral exists, follow the procedure below to locate
the open.
IMPORTANT
Neutral current may find a path around the open which...

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9. Locating Buried Streetlight Cables
9.1 Buried cables that bring power to streetlights are normally not energized in the daytime. Each
streetlight has a light sensitive switch that will open during daylight hours. Trying to locate these
cables using the passive power frequencies (either 50 or 60 Hz) will not work.
9.2 Street light cables appear to be floating (no grounds) since the supply is a transformer and the
light sensitive switch is open. This means there is no return path for a tracing signal...

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Section 4  CATV Cable Locating Techniques
1. Introduction
1.1 Read Section One of this manual to learn more general information about each of the following
tone application methods. The following paragraphs provide specific instruction on applying tone
for CATV (cable television) cable locating.
2. Applying Signal to CATV Cables: Induction Method
2.1 The Induction method broadcasts signal into an area.  No access to the cable is necessary.  Use
this only when there are no other buried conductors...

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3. Applying Signal to CATV Cables: Direct-Connect Method
3.1 The direct-connect method requires access to the cable shield.  Disconnect the cable at the
near-end where the Transmitter is connected.  Do not disconnect at the far-end (subscriberÕs
premises) since this supplies a far-end ground.  Perform the following steps to use the
direct-connect method.
3.2 Connect the red lead of the Transmitter to the cable shield and the black lead to the ground
rod.
3.3 Place the ground rod as far away from
the...