Cable and Pipe Locating
Techniques
for use with 3M
™
Dynatel
™
Cable and Pipe Locators
August 1998
80-6108-6216-3-C
1
Table of Contents
Section 1 The Basics of Cable Locating
1.
2.
3.
4.
5.
Introduction ........................................................................................................................... 7
Applying the Signal: The Direct Connect Method ................................................................. 8
Applying the Signal: The Induction Method ......................................................................... 9
Applying the Signal: The Dyna-Coupler Method ................................................................. 10
Other Locating Signal Sources ........................................................................................... 10
A. Passive Signals ............................................................................................................. 10
B. Power Frequencies ........................................................................................................11
C. Radio signals ..................................................................................................................11
D. Cable TV Signals ............................................................................................................11
E. Other Transmitted Signal Sources ................................................................................. 11
Choosing Trace Modes ....................................................................................................... 12
One Touch Gain adjustment ............................................................................................... 13
Locating Techniques ........................................................................................................... 14
A. Sweeping ....................................................................................................................... 14
B. Positioning ..................................................................................................................... 14
C. Tracing........................................................................................................................... 14
D. Identifying Cable By Depth-Current Measurement ........................................................ 15
E. Tracing Currents ............................................................................................................ 16
External DC Power and 5 Watt Output ............................................................................... 17
A. External DC Power ........................................................................................................ 17
B. 5 Watt Output ................................................................................................................ 17
6.
7.
8.
9.
Section 2 Telephone Cable Locating Techniques
1. Introduction ........................................................................................................................... 9
2. Applying Signal to Telephone Cable: Induction Method ....................................................... 9
3. Applying Signal to Telephone Cable: Direct-connect Method ............................................. 20
4. Applying Signal to Telephone Cable: Dyna-Coupler Method .............................................. 21
5. Locating Slack Loops and Butt Splices ............................................................................... 23
6. Locating Unknown Laterals ................................................................................................ 23
7. Locating Cables from Pedestals ......................................................................................... 24
8. Locating Service Drops ....................................................................................................... 25
9. Locating an Open End ........................................................................................................ 25
10. Identifying Cables .............................................................................................................. 25
11. Pair Identification ............................................................................................................... 26
12. Locating Splits ................................................................................................................... 27
13. Fiber Optic Locating .......................................................................................................... 28
A. Can the Fiber Be Traced? ............................................................................................. 28
B. Applying the Trace Signal .............................................................................................. 29
Attaching at CO or Remote Terminal Office .................................................................. 29
Attaching at the Splice Point ......................................................................................... 29
C. Tracing the Fiber Optic Cable........................................................................................ 30
Section 3 Power Cable Locating Techniques
1. Introduction ......................................................................................................................... 31
2. Applying Signal to Power Cables: Direct-connect Method ................................................. 31
A. Applying Signal to the Transformer ............................................................................... 31
B. Applying Signal at the Meter ......................................................................................... 31
C. Applying Signal to De-Energized Secondaries .............................................................. 32
3. Applying Signal to Power Cables: Induction Method .......................................................... 32
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4. Applying Signal to Power Cables: Dyna-Coupler Method .................................................. 33
A. Applying Signal to Primary Cables ................................................................................ 33
B. Applying Signal to Secondary Cables ........................................................................... 34
5. Identifying Slack Loops ....................................................................................................... 35
6. Identifying A Cable Open End ............................................................................................. 35
7. Identifying Primary Power Cables....................................................................................... 36
8. Locating Open Concentric Neutrals .................................................................................... 37
9. Locating Buried Streetlight Cables ..................................................................................... 38
Section 4 CATV Cable Locating Techniques
1.
2.
3.
4.
5.
6.
Introduction ......................................................................................................................... 39
Applying Signal to CATV Cables: Induction Method ........................................................... 39
Applying Signal to CATV Cables: Direct-Connect Method ................................................. 40
Applying Signal to CATV Cables: Dyna-Coupler Method ................................................... 41
Locating Cable Slack Loops ............................................................................................... 42
Locating Cables from Pedestals ......................................................................................... 42
Section 5 Pipe Locating Techniques
1. Introduction ......................................................................................................................... 43
2. Applying Signal to Pipe: Induction Method ......................................................................... 43
3. Applying Signal to Pipe: Direct-connect Method ................................................................. 44
A. Direct-connect Method on Tracer Wires ........................................................................ 45
4. Apply Signal to Pipe: Dyna-Coupler Method ...................................................................... 45
5. Locating Nonmetallic Pipe .................................................................................................. 46
6. Locating Pipe with Impressed Cathodic Protection ............................................................ 47
Section 6 Locating Faults
1. Introduction ......................................................................................................................... 49
2. Locating Sheath Faults ....................................................................................................... 50
A. Locating Sheath Faults Near Pedestals ........................................................................ 52
B. Locating Sheath Faults Under Pavement ...................................................................... 53
Perpendicular Method ................................................................................................... 53
Triangulation Method ..................................................................................................... 53
Extended Frame Methods ............................................................................................. 54
C. Finding a Fault without Tracing the Cable Path ............................................................. 55
D. Multiple Faults ............................................................................................................... 56
3. Locating Aerial Faults ......................................................................................................... 57
4. Locating Earth Faults Near the Meter Box .......................................................................... 58
5. Locating Earth Faults in Secondary Cable ......................................................................... 58
Section 7 Locating Active Duct Probes
1. Introduction ......................................................................................................................... 59
2. Locating the Active Duct Probe ........................................................................................... 59
3. Determining the Depth of the ADP ...................................................................................... 61
A. Determining ADP Depth with 500A/573A Cable Locators ............................................. 62
4. Locating Blockage or Collapsed Ducts ............................................................................... 63
5. Locating Sewer Pipe Problems Using a Video Camera ..................................................... 63
6. Locating a Flushing Hose Nozzle ....................................................................................... 63
"Dynatel" is a Trademark of 3M
4
This manual has been prepared to provide the most important written instruction material to date for
cable locating with 3M’s Cable and fault Locating products. It assumes a basic understanding of the
commonly used terms in telephone transmission and switching. Whenever this manual is reissued, the
reason(s) for reissue will be listed here. Comments concerning the contents or organization of this
document, as well as suggestions for improvement are welcomed.
Direct comments to:
3M Telecom Systems Division
Lab - Technical Communications
6801 River Place Boulevard
Austin, Texas 78726-9000
For Technical Service call: 800/426 8688
(outside the USA call 512/984 2575)
Glossary
AC
Amplitude
Abbreviation for Alternating Current.
The maximum value of a varying quantity. A signal on a buried cable will have a certain
amplitude which may be different from the signal on another buried cable. The receiver
electronics can detect and display the difference.
A general term used to denote a decrease in the magnitude of a signal from one point to
another.
A signal which can be heard by the human ear, typically from about 15 Hz to 15 kHz.
Property of a material which allows the passage of a signal or current.
Abbreviation for Hertz. A unit of frequency equaling one cycle per second.
A method of putting signal on a buried conductor by using a varying current in one circuit
(the transmitter) to produce a voltage in another nearby circuit (the buried conductor).
Abbreviation for kilo-Hertz. Hertz times 1000; Example: 2.7 kHz equals 2700 Hertz.
Abbreviation for kilo-Ohms. Ohms times 1000; Example: 2.5 kohms equals 2500 ohms.
Liquid Crystal Display.
Abbreviation for mega-Ohms. Ohms times 1,000,000. Example: 2.5 megohms equals
2,500,000 ohms.
Method of operation.
A receiver trace mode where the receiver will respond to signal on a buried cable by
indicating minimum signal directly over the cable.
Device for measuring electrical resistance.
A receiver trace mode where the receiver will respond to signal on a buried cable by
indicating maximum signal directly over the cable.
Property of a conductor which determines the current which will flow through it when a
particular voltage is applied. Measured in Ohms.
Abbreviation for root-mean-square. Used to designate the measurement of a voltmeter
when measuring 60 Hz. Example: 110 volts RMS.
A cable transmitting approximately 600 volts or less.
A method of finding the location of a point by taking observations at two of the corners of a
triangle. The point where the two observations cross is the third corner of the triangle and
the target location.
Device for measuring electrical potential difference.
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Attenuated
Audio
Conductive
Hz
Induction
kHz
k ohm
LCD
Megohms
Mode
Null
Ohmmeter
Peak
Resistance
RMS
Secondary
Triangulate
Voltmeter
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