UNITED STATES DEPARTMENT AGRICULTURE

Rural Utilities Service

BULLETIN 1753F-201(PC-4)

RD-GD-1997-23

SUBJECT: RUS Standard for Acceptance Tests and Measurements

of Telecommunications Plant

TO: All Telecommunications Borrowers

RUS Telecommunications Staff

EFFECTIVE DATE: June 2, 1997.

EXPIRATION DATE: Date of change in 7 CFR §§ 1755.400 through

1755.407 by rulemaking.

OFFICE OF PRIMARY INTEREST: Outside Plant Branch,

Telecommunications Standards Division.

PREVIOUS INSTRUCTIONS: This bulletin replaces RUS Bulletin

345-63, RUS Standard for Acceptance Tests and Measurements of

Telephone Plant, PC-4, issued May 20, 1976.

FILING INSTRUCTIONS: Discard RUS Bulletin 345-63, RUS Standard

for Acceptance Tests and Measurements of Telephone Plant, PC-4,

dated May 20, 1976, and replace it with this bulletin. File with

7 CFR 1755. This bulletin is available to the RUS staff on

RUSNET (text only) and can be accessed via Internet at

http://www.usda.gov/rus/home/home.htm

PURPOSE: This standard covers RUS acceptance tests and

measurements to be performed on installed copper and fiber optic

cable telecommunications plant. This bulletin is a reformat of

the text codified in 7 CFR 1755.400 through 7 CFR 1755.407

published at 62 FR 23958, dated May 2, 1997.

Every effort has been made to ensure the accuracy of this

document. However, in case of discrepancies, the regulations at 7 

CFR 1755.400 through 7 CFR 1755.407 are the authorized sources.

Wally Beyer 8/26/97

Administrator Date

Disclaimer: The contents of this guidance document does not have the 

force and effect of law and is not meant to bind the public in any way. 

This document is intended only to provide clarity to the public 

regarding existing requirements under the law or agency policies
Bulletin 1753F-201(PC-4)

Page 2

TABLE OF CONTENTS

CFR to Bulletin Conversion Table ......................... 6

Abbreviations ........................................... 12

Definitions ............................................. 13

1. Scope ................................................... 14

2. Ground Resistance Measurements .......................... 15

2.1 .................................................. 15

2.2 .................................................. 15

2.3 Method of Measurement ............................ 15

2.4 Test Equipment ................................... 15

2.5 Applicable Results ............................... 15

2.6 Data Records ..................................... 15

2.7 Probable Causes of Nonconformance ................ 16

3. Copper Cable Telecommunications Plant Measurements ...... 16

3.1 Shield or Shield/Armor Continuity ................ 16

3.2 Conductor Continuity ............................. 21

3.3 DC Insulation Resistance (IR) .................... 21

3.4 DC Loop Resistance and DC Resistance

 Unbalance Measurement ............................ 24

3.5 Subscriber Loop Measurement (Loop Checking) ...... 26

3.6 One-Person Open Circuit Measurement

 (Subscriber Loops) ............................... 33

3.7 Carrier Insertion Loss Measurement

 (Carrier Frequencies) ............................ 37

4. Fiber Optic Cable Telecommunications Plant

Measurements ............................................ 40

4.1 Armor Continuity ................................. 40

4.2 Fiber Optic Splice Loss Measurement .............. 41

4.3 End-to-End Attenuation Measurement ............... 43

4.4 End-to-End Fiber Signature Measurement ........... 43

5. Voiceband Data Transmission Measurements ................ 44

5.1 Introduction ..................................... 44

5.2 Signal-to-C Notched Noise (S/CNN)

 Measurement ...................................... 44

5.3 Signal-to-Intermodulation Distortion (S/IMD)

 Measurement ...................................... 45

5.4 Envelope Delay Distortion (EDD) Measurement ...... 46

5.5 Amplitude Jitter (AJ) Measurement ................ 47

5.6 Phase Jitter (PJ) Measurement .................... 48

5.7 Impulse Noise Measurement ........................ 49
Bulletin 1753F-201(PC-4)

Page 3

TABLE OF CONTENTS - Continued

6. Shield or Armor Ground Resistance Measurements .......... 50

6.1 .................................................. 50

6.2 Method of Measurement ............................ 50

6.3 Test Equipment ................................... 50

6.4 Applicable Results ............................... 50

6.5 Data Record ...................................... 51

6.6 Probable Cause for Nonconformance ................ 51

7. Data Formats ............................................ 52

FORMAT I OUTSIDE PLANT ACCEPTANCE TEST - SUBSCRIBER

LOOPS ....................................... 53

FORMAT II OUTSIDE PLANT ACCEPTANCE TEST - TRUNK

CIRCUITS ................................... 54

FORMAT III OUTSIDE PLANT ACCEPTANCE TEST - T1 or T1C

CARRIER PAIRS ............................. 55

FORMAT IV OUTSIDE PLANT ACCEPTANCE TEST - STATION

CARRIER PAIRS .............................. 56

FORMAT V OUTSIDE PLANT ACCEPTANCE TEST - FIBER OPTIC

TELECOMMUNICATIONS PLANT .................... 57

FORMAT VI VOICEBAND DATA TRANSMISSION - NONLOADED

SUBSCRIBER LOOPS ........................... 58

FORMAT VII VOICEBAND DATA TRANSMISSION - TRUNK

CIRCUITS .................................. 59

TABLES AND FIGURES

TABLE 1 Shield Resistance @68°F (20°C) Cable Diameters

Versus Shield Types (English Units) ................ 18

TABLE 2 Shield Resistance @68°F (20°C) Cable Diameters

Versus Shield Types (Metric Units) ................. 19

TABLE 3 DC Loop Resistance @68°F (20°C) .................... 25

TABLE 4 Frequency Attenuation @68°F (20°C) D66 Loaded

Exchange Cables 83 Nanofarads (nF)/mile (52 nF/km) . 29

TABLE 5 Frequency Attenuation @68°F (20°C) H88 Loaded

Exchange Cables 83 nF/mile (52 nF/km) .............. 30

TABLE 6 Frequency Attenuation @68°F (20°C) Nonloaded

Exchange Cables 83 nF/mile (52 nF/km) .............. 31
Bulletin 1753F-201(PC-4)

Page 4

TABLES AND FIGURES - Continued

TABLE 7 Cable Attenuation @68°F (20°C) Filled Cables -

Solid Insulation ................................... 38

TABLE 8 Cable Attenuation @68°F (20°C) Filled Cables -

Expanded Insulation ................................ 39

FIGURE 1 GROUND RESISTANCE MEASUREMENT ..................... 60

FIGURE 2 SHIELD OR SHIELD/ARMOR RESISTANCE MEASUREMENT ..... 61

FIGURE 3 DC INSULATION RESISTANCE MEASUREMENT .............. 62

FIGURE 4 DC LOOP RESISTANCE MEASUREMENT .................... 63

FIGURE 5 DC LOOP RESISTANCE UNBALANCE MEASUREMENT .......... 64

FIGURE 6 INSERTION LOSS AND FREQUENCY RESPONSE

MEASUREMENT AT SUBSCRIBER LOCATION USING LOOP

CHECKING EQUIPMENT ................................ 65

FIGURE 7 NOISE MEASUREMENT AT SUBSCRIBER LOCATION

USING LOOP CHECKING EQUIPMENT ..................... 66

FIGURE 8 ONE-PERSON OPEN CIRCUIT MEASUREMENT

IMPEDANCE OR PULSE RETURN PATTERN ................. 67

FIGURE 9 ONE-PERSON OPEN CIRCUIT MEASUREMENT

RETURN LOSS BALANCED TO ARTIFICIAL LINE ........... 68

FIGURE 10 ONE-PERSON OPEN CIRCUIT MEASUREMENT

STRUCTURAL RETURN LOSS USING LEVEL TRACER ........ 69

FIGURE 11 CARRIER FREQUENCY INSERTION LOSS MEASUREMENT

CABLE FACILITIES ................................. 70

FIGURE 12 EFFECTS OF BRIDGE TAPS ON ATTENUATION ............ 71

FIGURE 13 EFFECTS OF LOADING COILS ON ATTENUATION .......... 72

FIGURE 14 FIBER OPTIC FIELD SPLICE LOSS MEASUREMENT ........ 73

FIGURE 15 FIBER OPTIC CENTRAL OFFICE SPLICE

LOSS MEASUREMENT ................................. 74

FIGURE 16 END-TO-END FIBER OPTIC ATTENUATION MEASUREMENT

SHOWING MEASUREMENT IN ONE DIRECTION ONLY ........ 75
Bulletin 1753F-201(PC-4)

Page 5

TABLES AND FIGURES - Continued

FIGURE 17 END-TO-END FIBER OPTIC SIGNATURE MEASUREMENT

SHOWING MEASUREMENT IN ONE DIRECTION ONLY ........ 76

FIGURE 18 SHIELD OR ARMOR GROUND RESISTANCE MEASUREMENT .... 77

INDEX:

Outside Plant

Construction

Acceptance Testing

Telecommunications
Bulletin 1753F-201(PC-4)

Page 6

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

7 CFR 1755.400 Bulletin Title

7 CFR 1755.401 1.

(a) 1.1

(a)(1) 1.1.1

(a)(2) 1.1.2

(a)(3) 1.1.3

(a)(4) 1.1.4

(a)(5) 1.1.5

(b) 1.2

(c) 1.3

(d) 1.4

(e) 1.5

- 1.6

7 CFR 1755.402 2.

(a) 2.1

(b) 2.2

(c) 2.3

(d) 2.4

(e) 2.5

(e)(1) 2.5.1

(e)(2) 2.5.2

(e)(3) 2.5.3

(f) 2.6

(g) 2.7

7 CFR 1755.403 3.

(a) 3.1

(a)(1) 3.1.1

(a)(2) 3.1.2

(a)(3) 3.1.3

(a)(3)(i) 3.1.3.1

(a)(3)(ii) 3.1.3.2

(a)(4) 3.1.4

(a)(4)(i) 3.1.4.1

(a)(4)(ii) 3.1.4.2

(a)(5) 3.1.5

(a)(5)(i) 3.1.5.1

(a)(5)(ii) 3.1.5.2

(a)(5)(iii) 3.1.5.3

(a)(5)(iv) 3.1.5.4

(a)(5)(v) 3.1.5.5

(a)(6) 3.1.6

(a)(7) 3.1.7

(b) 3.2

(c) 3.3

(c)(1) 3.3.1

(c)(2) 3.3.2

(c)(2)(i) 3.3.2.1

(c)(2)(ii) 3.3.2.2

(c)(2)(iii) 3.3.2.3
Bulletin 1753F-201(PC-4)

Page 7

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

(c)(3) 3.3.3

(c)(3)(i) 3.3.3.1

(c)(3)(ii) 3.3.3.2

(c)(3)(iii) 3.3.3.3

(c)(4) 3.3.4

(c)(4)(i) 3.3.4.1

(c)(4)(ii) 3.3.4.2

(c)(4)(iii) 3.3.4.3

(c)(4)(iv) 3.3.4.4

(c)(4)(v) 3.3.4.5

(c)(5) 3.3.5

(c)(6) 3.3.6

(c)(6)(i) 3.3.6.1

(c)(6)(ii) 3.3.6.2

(c)(6)(iii) 3.3.6.3

(d) 3.4

(d)(1) 3.4.1

(d)(2) 3.4.2

(d)(3) 3.4.3

(d)(4) 3.4.4

(d)(5) 3.4.5

(d)(6) 3.4.6

(d)(6)(i) 3.4.6.1

(d)(6)(ii) 3.4.6.2

(d)(6)(ii)(A) 3.4.6.2.1

(d)(6)(ii)(B) 3.4.6.2.2

(d)(6)(ii)(C) 3.4.6.2.3

(d)(6)(ii)(D) 3.4.6.2.4

(d)(6)(iii) 3.4.6.3

(d)(6)(iv) 3.4.6.4

(d)(6)(v) 3.4.6.5

(d)(6)(vi) 3.4.6.6

(d)(7) 3.4.7

(d)(8) 3.4.8

(e) 3.5

(e)(1) 3.5.1

(e)(2) 3.5.2

(e)(3) 3.5.3

(e)(4) 3.5.4

(e)(4)(i) 3.5.4.1

(e)(4)(ii) 3.5.4.2

(e)(5) 3.5.5

(e)(5)(i) 3.5.5.1

(e)(5)(ii) 3.5.5.2

(e)(6) 3.5.6

(e)(6)(i) 3.5.6.1

(e)(6)(i)(A) 3.5.6.1.1

(e)(6)(i)(B) 3.5.6.1.2

(e)(6)(i)(C) 3.5.6.1.3
Bulletin 1753F-201(PC-4)

Page 8

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

(e)(6)(i)(D) 3.5.6.1.4

(e)(6)(i)(E) 3.5.6.1.5

(e)(6)(i)(F) 3.5.6.1.6

(e)(6)(i)(G) 3.5.6.1.7

(e)(6)(i)(H) 3.5.6.1.8

(e)(6)(ii) 3.5.6.2

(e)(7) 3.5.7

(e)(8) 3.5.8

(e)(8)(i) 3.5.8.1

(e)(8)(ii) 3.5.8.2

(f) 3.6

(f)(1) 3.6.1

(f)(2) 3.6.2

(f)(3) 3.6.3

(f)(4) 3.6.4

(f)(5) 3.6.5

(f)(5)(i) 3.6.5.1

(f)(5)(ii) 3.6.5.2

(f)(5)(iii) 3.6.5.3

(f)(6) 3.6.6

(f)(7) 3.6.7

(f)(7)(i) 3.6.7.1

(f)(7)(ii) 3.6.7.2

(f)(7)(iii) 3.6.7.3

(f)(7)(iv) 3.6.7.4

(f)(7)(v) 3.6.7.5

(f)(7)(vi) 3.6.7.6

(f)(8) 3.6.8

(f)(8)(i) 3.6.8.1

(f)(8)(ii) 3.6 8.2

(f)(9) 3.6.9

(g) 3.7

(g)(1) 3.7.1

(g)(2) 3.7.2

(g)(3) 3.7.3

(g)(4) 3.7.4

(g)(4)(i) 3.7.4.1

(g)(4)(ii) 3.7.4.2

(g)(4)(iii) 3.7.4.3

(g)(4)(iv) 3.7.4.4

(g)(5) 3.7.5

(g)(6) 3.7.6

7 CFR 1755.404 4.

(a) 4.1

(a)(1) 4.1.1

(a)(2) 4.1.2

(a)(3) 4.1.3

(a)(4) 4.1.4

(a)(5) 4.1.5
Bulletin 1753F-201(PC-4)

Page 9

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

(a)(6) 4.1.6

(a)(7) 4.1.7

(b) 4.2

(b)(1) 4.2.1

(b)(2) 4.2.2

(b)(2)(i) 4.2.2.1

(b)(2)(ii) 4.2.2.2

(b)(3) 4.2.3

(b)(4) 4.2.4

(b)(4)(i) 4.2.4.1

(b)(4)(ii) 4.2.4.2

(b)(4)(iii) 4.2.4.3

(b)(4)(iv) 4.2.4.4

(b)(4)(v) 4.2.4.5

(b)(4)(vi) 4.2.4.6

(b)(5) 4.2.5

(b)(6) 4.2.6

(c) 4.3

(c)(1) 4.3.1

(c)(2) 4.3.2

(c)(3) 4.3.3

(c)(4) 4.3.4

(c)(5) 4.3.5

(c)(6) 4.3.6

(d) 4.4

(d)(1) 4.4.1

(d)(2) 4.4.2

(d)(3) 4.4.3

(d)(4) 4.4.4

(d)(5) 4.4.5

(d)(6) 4.4.6

7 CFR 1755.405 5.

(a) 5.1

(b) 5.2

(b)(1) 5.2.1

(b)(2) 5.2.2

(b)(3) 5.2.3

(b)(4) 5.2.4

(b)(5) 5.2.5

(b)(6) 5.2.6

(b)(7) 5.2.7

(c) 5.3

(c)(1) 5.3.1

(c)(2) 5.3.2

(c)(3) 5.3.3

(c)(4) 5.3.4

(c)(5) 5.3.5

(c)(6) 5.3.6

(c)(7) 5.3.7
Bulletin 1753F-201(PC-4)

Page 10

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

(c)(8) 5.3.8

(c)(9) 5.3.9

(d) 5.4

(d)(1) 5.4.1

(d)(2) 5.4.2

(d)(3) 5.4.3

(d)(4) 5.4.4

(d)(5) 5.4.5

(d)(6) 5.4.6

(d)(7) 5.4.7

(d)(8) 5.4.8

(e) 5.5

(e)(1) 5.5.1

(e)(2) 5.5.2

(e)(3) 5.5.3

(e)(4) 5.5.4

(e)(5) 5.5.5

(e)(6) 5.5.6

(e)(7) 5.5.7

(e)(8) 5.5.8

(e)(9) 5.5.9

(f) 5.6

(f)(1) 5.6.1

(f)(2) 5.6.2

(f)(3) 5.6.3

(f)(4) 5.6.4

(f)(5) 5.6.5

(f)(6) 5.6.6

(f)(7) 5.6.7

(f)(8) 5.6.8

(f)(9) 5.6.9

(g) 5.7

(g)(1) 5.7.1

(g)(2) 5.7.2

(g)(3) 5.7.3

(g)(4) 5.7.4

(g)(5) 5.7.5

(g)(6) 5.7.6

(g)(7) 5.7.7

7 CFR 1755.406 6.

(a) 6.1

(b) 6.2

(b)(1) 6.2.1

(b)(2) 6.2.2

(c) 6.3

(c)(1) 6.3.1

(c)(2) 6.3.2

(c)(3) 6.3.3

(c)(4) 6.3.4
Bulletin 1753F-201(PC-4)

Page 11

CFR TO BULLETIN CONVERSION TABLE

7 CFR 1755. 400 to 7 CFR 1755.407 Bulletin 1753F-201

(d) 6.4

(d)(1) 6.4.1

(d)(2) 6.4.2

(d)(3) 6.4.3

(d)(4)(i) 6.4.4

(d)(4)(ii) 6.4.5

(d)(5) 6.4.6

(e) 6.5

(f) 6.6

(f)(1) 6.6.1

(f)(2) 6.6.2

(f)(3) 6.6.3

7 CFR 1755.407 7.

- 7.1
Bulletin 1753F-201(PC-4)

Page 12

ABBREVIATIONS

ac Alternating current

ANSI American National Standards Institute

AJ Amplitude jitter

AWG American Wire Gauge

°C Centigrade temperature scale

CFSRL Critical Frequency of Structural Return Loss

CO Central office

dB Decibels

dBm0 Decibels relative to one milliwatt, referred to a

zero transmission level point

dBrnc Decibels above Reference Noise C-Message Weighted

dBrnC0 Decibels relative to one picowatt reference noise

level, measured with C-message frequency weighting,

referred to a zero transmission level point

dc Direct current

EED Envelope Delay Distortion

°F Fahrenheit temperature scale

f Frequency

ft Feet

Hz Hertz

IEEE Institute of Electrical and Electronic Engineers

IMD Intermodulation Distortion

in. Inches

IR Insulation resistance

kHz Kilohertz

km Kilometer

m Meter

Mb/s Megabit per second

MDF Main Distributing Frame

MGB Master Ground Bar

mm Millimeter

nF Nanofarad

NID Network interface device

NM Circuit noise

OTDR Optical time domain reflectometer

% Percent

°p-p Degrees peak-to-peak

PBN Precision balance network

PI Power influence

PJ Phase jitter

RED Relative Envelope Delay

RST Remote Switching Terminal

RUS Rural Utilities Service

S/CNN Signal-to-C-Notched Noise

S/IMD Signal-to-Intermodulation Delay

SRL Structural return loss

TE&CM Telecommunications Engineering and Construction 

Manual

UI Unit interval
Bulletin 1753F-201(PC-4)

Page 13

DEFINITIONS

Amplitude Jitter: A measurement of any fluctuation in the peak

amplitude value of a fixed tone signal at 1,004 Hz from its

nominal value.

C-Message Weighted: A weighting derived from listening tests, to

indicate the relative annoyance or speech impairment by an

interfering signal of frequency (f) as heard through a “500-type”

telephone set.

Envelope Delay Distortion: A measure of the linearity or

uniformity of the phase versus frequency characteristics of a

transmission facility.

D66 Loading: A specific loading scheme using a 66 millihenry

inductor spaced nominally at 4,500 ft (1,371 m) intervals.

H88 Loading: A specific loading scheme using an 88 millihenry

inductor spaced nominally at 6,000 ft (1,829 m) intervals.

Impulse Noise: A measurement of the presence of unusually large

noise excursions of short duration that are beyond the normal

background noise levels on a facility.

Phase Jitter: A measure of any fluctuation in the zero crossings

of a fixed tone signal (usually 1,004 Hz) from their nominal

position in time within the voiceband.

Signal-to-C Notched Noise: A logarithmic ratio expressed in dB

of a 1,004 Hz holding tone signal compared to C-message weighted

noise level.

Signal-to-Intermodulation Distortion: A measure of the

distortion produced by extraneous frequency cross products, known

as intermodulation products, when a multi-tone signal is applied

to a system.

T1 Digital Carrier: A 24 channel 1.544 megabit per second (Mb/s)

pulse code modulation system.

T1C Digital Carrier: A 48 channel 3.152 Mb/s pulse code

modulation system.
Bulletin 1753F-201(PC-4)

Page 14

1. SCOPE

1.1 Acceptance tests outlined in this bulletin are applicable to

plant constructed by contract or force account. This testing

standard provides for the following:

1.1.1 Specific types of tests or measurements for the different

types of telecommunications plant and equipment;

1.1.2 The method of measurement and types of measuring

equipment;

1.1.3 The expected results and tolerances permitted to meet the

acceptable standards and objectives;

1.1.4 Suggested formats for recording the results of the

measurements and tests; and

1.1.5 Some probable causes of nonconformance and methods for

corrective action, where possible.

1.2 Alternative methods of measurements that provide suitable

alternative results shall be permitted with the concurrence of

the Rural Utilities Service (RUS).

1.3 For the purpose of this testing standard, a "measurement"

shall be defined as an evaluation where quantitative data is

obtained (e.g., resistance in ohms, structural return loss in

decibels (dB), etc.) and a "test" shall be defined as an

evaluation where no quantitative data is obtained (e.g., a check

mark indicating conformance is usually the result of the test).

1.4 The sequence of tests and measurements described in this

standard have been prepared as a guide. Variations from the

sequence may be necessary on an individual application basis.

1.5 There is some overlap in the methods of testing shown; also,

the extent of each phase of testing may vary on an individual

basis. The borrower shall determine the overall plan of testing,

the need and extent of testing, and the responsibility for each

phase of testing.

1.6 Copies of the American National Standards Institute (ANSI)

T1.506-1990, “American National Standard for Telecommunications -

Network Performance - Transmission Specifications for Switched

Exchange Access Network,” including supplement ANSI T1.506a-1992,

and American National Standards Institute/Institute of Electrical

and Electronics Engineers (ANSI/IEEE) 743-1984, “IEEE Standard

Methods and Equipment for Measuring the Transmission

Characteristics of Analog Voice Frequency Circuits,” referenced

in this standard can both be obtained for nominal fees at the

address indicated below:
Bulletin 1753F-201(PC-4)

Page 15

ANSI, Customer Service

11 West 42nd Street

New York, New York 10036

Telephone No. (212) 642-4900

2. GROUND RESISTANCE MEASUREMENTS

2.1 The resistance of the central office (CO) and the remote

switching terminal (RST) ground shall be measured before and

after it has been bonded to the master ground bar (MGB) where it

is connected to the building electric service ground.

2.2 The ground resistance of electronic equipment such as span

line repeaters, carrier terminal equipment, concentrators, etc.

shall be measured.

2.3 Method of Measurement: The connection of test equipment for

the ground resistance measurement shall be as shown in Figure 1.

Refer to RUS Bulletin 1751F-802, "Electrical Protection Grounding

Fundamentals," for a comprehensive discussion of ground

resistance measurements.

2.4 Test Equipment: The test equipment for making this

measurement is shown in Figure 1.

2.5 Applicable Results:

2.5.1 For the CO and RST, the resistance after the bond has been

made to the MGB electric service ground shall not exceed 5 ohms.

Where the measured ground resistance exceeds 5 ohms, the borrower

shall determine what additional grounding, if any, shall be

provided.

2.5.2 For electronic equipment, the ground resistance shall not

exceed 25 ohms. Where the measured ground resistance exceeds 25

ohms, the borrower shall determine what additional grounding, if

any, shall be provided.

2.5.3 When ground resistance measurements exceed the ground

resistance requirements of Paragraphs 2.5.1 and 2.5.2 of this

bulletin, refer to RUS Bulletin 1751F-802, "Electrical Protection

Grounding Fundamentals," for suggested methods of reducing the

ground resistance.

2.6 Data Record: Results of the CO and RST ground resistance

measurements shall be recorded. A suggested format similar to

Format I, Outside Plant Acceptance Tests - Subscriber Loops, in

Paragraph 7 of this bulletin or a format specified in the

applicable construction contract may be used. Results of the

electronic equipment ground resistance measurements shall be

recorded. A suggested format similar to Format II, Outside Plant

Acceptance Tests - Trunk Circuits, in Paragraph 7 of this
Bulletin 1753F-201(PC-4)

Page 16

bulletin or a format specified in the applicable construction

contract may be used. Data showing approximate moisture content

of the soil at the time of measurement, the temperature, the type

of soil and a description of the test equipment used shall also

be included.

2.7 Probable Causes of Nonconformance: Refer to RUS Bulletin

1751F-802, "Electrical Protection Grounding Fundamentals," and

Telecommunications Engineering and Construction Manual (TE&CM)

Section 810, "Electrical Protection of Electronic Analog and

Digital Central Office Equipment," for possible causes of

nonconformance and suggested methods for corrective action.

3. COPPER CABLE TELECOMMUNICATIONS PLANT MEASUREMENTS

3.1 Shield or Shield/Armor Continuity:

3.1.1 Tests and measurements shall be made to ensure that cable

shields or shield/armors are electrically continuous. There are

two areas of concern. The first is shield or shield/armor

bonding within a pedestal or splice and the second is shield or

shield/armor continuity between pedestals or splices.

3.1.2 Measurement techniques outlined here for verification of

shield or shield/armor continuity are applicable to buried cable

plant. Measurements of shield continuity between splices in

aerial cable plant should be made prior to completion of

splicing. Conclusive results cannot be obtained on aerial plant

after all bonds have been completed to the supporting strand,

multigrounded neutral, etc.

3.1.3 Method of Measurement:

3.1.3.1 The shield or shield/armor resistance measurements shall

be made between pedestals or splices using either a Wheatstone

bridge or a volt-ohm meter. For loaded plant, measurements shall

be made on cable lengths that do not exceed one load section.

For nonloaded plant, measurements shall be made on cable lengths

that do not exceed 5,000 feet (ft) (1,524 meters (m)). All

bonding wires shall be removed from the bonding lugs at the far

end of the cable section to be measured. The step-by-step

measurement procedure shall be as shown in Figure 2.

3.1.3.2 Cable shield or shield/armor continuity within pedestals

or splices shall be measured with a cable shield splice

continuity test set. The step-by-step measurement procedure

outlined in the manufacturer's operating instructions for the

specific test equipment being used shall be followed.
Bulletin 1753F-201(PC-4)

Page 17

3.1.4 Test Equipment:

3.1.4.1 The test equipment for measuring cable shield or

shield/armor resistance between pedestals or splices is shown in

Figure 2.

3.1.4.2 A cable shield splice continuity tester shall be used to

measure shield or shield/armor continuity within pedestals or

splices.

3.1.5 Applicable Results:

3.1.5.1 The shield or shield/armor resistance per 1000 ft and

per kilometer (km) for cable diameters and types of shielding

materials are given in Table 1 (English Units) and Table 2

(Metric Units), respectively as follows:
Bulletin 1753F-201(PC-4)

Page 18

Table 1 - Shield Resistance @ 68°F (20°C)

Cable Diameters Versus Shield Types

(English Units)

Outside Diameter Nominal Resistance ohm/1000 ft

Inches (in.) A BCDE F

0.40 - 0.49 0.77 1.54 1.65 1.96 2.30 5.51

0.50 - 0.59 0.64 1.28 1.37 1.63 1.91 4.58

0.60 - 0.69 0.51 1.03 1.10 1.31 1.53 3.67

0.70 - 0.79 0.44 0.88 0.94 - 1.31 3.14

0.80 - 0.89 0.38 0.77 0.82 - 1.14 2.74

0.90 - 0.99 0.35 0.69 0.74 - 1.03 2.47

1.00 - 1.09 0.31 0.62 0.66 - 0.92 2.20

1.10 - 1.19 0.28 0.56 0.60 - 0.84 2.00

1.20 - 1.29 0.26 0.51 0.55 - 0.77 1.84

1.30 - 1.39 0.24 0.48 0.51 - 0.71 1.70

1.40 - 1.49 0.22 0.44 0.47 - 0.65 1.57

1.50 - 1.59 0.21 0.41 0.44 - 0.61 1.47

1.60 - 1.69 0.19 0.38 0.41 - 0.57 1.37

1.70 - 1.79 0.18 0.37 0.39 - 0.54 1.30

1.80 - 1.89 0.17 0.35 0.37 - 0.51 1.24

1.90 - 1.99 0.16 0.33 0.35 - 0.49 1.17

2.00 - 2.09 0.15 0.31 0.33 - 0.46 1.10

2.10 - 2.19 0.15 0.29 0.31 - 0.43 1.03

2.20 - 2.29 0.14 0.28 0.30 - 0.42 1.00

2.30 - 2.39 0.14 0.27 0.29 - 0.40 0.97

2.40 - 2.49 0.13 0.25 0.27 - 0.38 0.90

2.50 - 2.59 0.12 0.24 0.26 - 0.36 0.87

2.60 - 2.69 0.12 0.23 0.25 - 0.35 0.83

2.70 - 2.79 0.11 0.22 0.24 - 0.33 0.80

2.80 - 2.89 0.11 0.22 0.24 - 0.33 0.80

2.90 - 2.99 0.11 0.22 0.23 - 0.32 0.77

3.00 - 3.09 0.10 0.21 0.22 - 0.31 0.73

3.10 - 3.19 0.10 0.20 0.21 - 0.29 0.70

3.20 - 3.29 0.10 0.20 0.21 - 0.29 0.70

3.30 - 3.39 0.09 0.19 0.20 - 0.28 0.67

3.40 - 3.49 0.09 0.18 0.19 - 0.26 0.63

3.50 - 3.59 0.09 0.18 0.19 - 0.26 0.63

3.60 - 3.69 0.08 0.17 0.18 - 0.25 0.60

3.70 - 3.79 0.08 0.17 0.18 - 0.25 0.60

3.80 - 3.89 0.08 0.16 0.17 - 0.24 0.57

3.90 - 3.99 0.08 0.16 0.17 - 0.24 0.57

4.00 - 4.99 0.07 0.15 0.16 - 0.22 0.53

Where: Column A - 10 mil Copper shield.

Column B - 5 mil Copper shield.

Column C - 8 mil Coated Aluminum and 8 mil Coated

Aluminum/6 mil Coated Steel shields.

Column D - 7 mil Alloy 194 shield.

Column E - 6 mil Alloy 194 and 6 mil Copper Clad

Stainless Steel shields.

Column F - 5 mil Copper Clad Stainless Steel and

5 mil Copper Clad Alloy Steel shields.
Bulletin 1753F-201(PC-4)

Page 19

Table 2 - Shield Resistance @ 68°F (20°C)

Cable Diameters Versus Shield Types

(Metric Units)

Outside Diameter Nominal Resistance ohm/km

Millimeters (mm) A BCDE F

10.2 - 12.5 2.53 5.05 5.41 6.43 7.55 18.08

12.7 - 15.0 2.10 4.20 4.49 5.35 6.27 15.03

15.2 - 17.5 1.67 3.38 3.61 4.30 5.02 12.04

17.8 - 20.1 1.44 2.89 3.08 - 4.30 10.30

20.3 - 22.6 1.25 2.53 2.69 - 3.74 8.99

22.9 - 25.1 1.15 2.26 2.43 - 3.38 8.10

25.4 - 27.7 1.02 2.03 2.16 - 3.02 7.22

27.9 - 30.2 0.92 1.84 1.97 - 2.76 6.56

30.5 - 32.8 0.85 1.67 1.80 - 2.53 6.04

33.0 - 35.3 0.79 1.57 1.67 - 2.33 5.58

35.6 - 37.8 0.72 1.44 1.54 - 2.13 5.15

38.1 - 40.4 0.69 1.34 1.44 - 2.00 4.82

40.6 - 42.9 0.62 1.25 1.34 - 1.87 4.49

43.2 - 45.5 0.59 1.21 1.28 - 1.77 4.26

45.7 - 48.0 0.56 1.15 1.21 - 1.67 4.07

48.3 - 50.5 0.52 1.08 1.15 - 1.61 3.84

50.8 - 53.1 0.49 1.02 1.08 - 1.51 3.61

53.3 - 55.6 0.49 0.95 1.02 - 1.41 3.38

55.9 - 58.2 0.46 0.92 0.98 - 1.38 3.28

58.4 - 60.7 0.46 0.89 0.95 - 1.31 3.18

61.0 - 63.2 0.43 0.82 0.89 - 1.25 2.95

63.5 - 65.8 0.39 0.79 0.85 - 1.18 2.85

66.0 - 68.3 0.39 0.75 0.82 - 1.15 2.72

68.6 - 70.9 0.36 0.72 0.79 - 1.08 2.62

71.1 - 73.4 0.36 0.72 0.79 - 1.08 2.62

73.7 - 75.9 0.36 0.72 0.75 - 1.05 2.53

76.2 - 78.5 0.33 0.69 0.72 - 1.02 2.39

78.7 - 81.0 0.33 0.66 0.69 - 0.95 2.30

81.3 - 83.6 0.33 0.66 0.69 - 0.95 2.30

83.6 - 86.1 0.29 0.62 0.66 - 0.92 2.20

86.4 - 88.6 0.29 0.59 0.62 - 0.85 2.07

88.9 - 91.2 0.29 0.59 0.62 - 0.85 2.07

91.4 - 93.7 0.26 0.56 0.59 - 0.82 1.97

94.0 - 96.3 0.26 0.56 0.59 - 0.82 1.97

96.5 - 98.8 0.26 0.52 0.56 - 0.79 1.87

99.1 - 101.3 0.26 0.52 0.56 - 0.79 1.87

101.6 - 103.9 0.23 0.49 0.52 - 0.72 1.74

Where: Column A - 10 mil Copper shield.

Column B - 5 mil Copper shield.

Column C - 8 mil Coated Aluminum and 8 mil Coated

Aluminum/6 mil Coated Steel shields.

Column D - 7 mil Alloy 194 shield.

Column E - 6 mil Alloy 194 and 6 mil Copper Clad

Stainless Steel shields.

Column F - 5 mil Copper Clad Stainless Steel and

5 mil Copper Clad Alloy Steel shields.
Bulletin 1753F-201(PC-4)

Page 20

3.1.5.2 All values of shield and shield/armor resistance

provided in Tables 1 and 2 in Paragraph 3.1.5.1 of this bulletin

are considered approximations. If the measured value corrected

to 68°F (20°C) is within ± 30 percent (%) of the value shown in

Table 1 or 2, the shield and shield/armor shall be assumed to be

continuous.

3.1.5.3 To correct the measured shield resistance to the

reference temperature of 68°F (20°C) use the following formulae:

R68 = Rt / [1 + A(t - 68)] for English Units

R20 = Rt / [1 + A(t - 20)] for Metric Units

Where:

R68 = Shield resistance corrected to 68°F in ohms.

R20 = Shield resistance corrected to 20°C in ohms.

Rt = Shield resistance at measurement temperature

in ohms.

A = Temperature coefficient of the shield tape.

t = Measurement temperature in °F or (°C).

3.1.5.4 The temperature coefficients (A) for the shield tapes to

be used in the formulae referenced in Paragraph 3.1.5.3 of this

bulletin are as follows:

a. 5 and 10 mil copper = 0.0021 for English units and

0.0039 for Metric units;

b. 8 mil coated aluminum and 8 mil coated aluminum/6 mil

coated steel = 0.0022 for English units and 0.0040 for

Metric units;

c. 5 mil copper clad stainless steel and 5 mil copper clad

alloy steel = 0.0024 for English units and 0.0044 for

Metric units;

d. 6 mil copper clad stainless steel = 0.0019 for English

units and 0.0035 for Metric units; and

e. 6 and 7 mil alloy 194 = 0.0013 for English units and

0.0024 for Metric units.

3.1.5.5 When utilizing shield continuity testers to measure

shield and shield/armor continuity within pedestals or splices,

refer to the manufacturer's published information covering the

specific test equipment to be used and for anticipated results.
Bulletin 1753F-201(PC-4)

Page 21

3.1.6 Data Record: Measurement data from shield continuity

tests shall be recorded together with anticipated Table 1 or 2

values (see Paragraph 3.1.5.1 of this bulletin) in an appropriate

format to permit comparison. The recorded data shall include

specific location, cable size, cable type, type of shield or

shield/armor, if known, etc.

3.1.7 Probable Causes for Nonconformance: Among probable causes

for nonconformance are broken or damaged shields or

shield/armors, bad bonding harnesses, poorly connected bonding

clamps, loose bonding lugs, etc.

3.2 Conductor Continuity: After placement of all cable and wire

plant has been completed and joined together in continuous

lengths, tests shall be made to ascertain that all pairs are free

from grounds, shorts, crosses, and opens, except for those pairs

indicated as being defective by the cable manufacturer. The

tests for grounds, shorts, crosses, and opens are not separate

tests, but are inherent in other acceptance tests discussed in

this section. The test for grounds, shorts, and crosses is

inherent when conductor insulation resistance measurements are

conducted per Paragraph 3.3 of this bulletin, while tests for

opens are inherent when tests are conducted for loop resistance,

insertion loss, noise, or return loss measurements, per

Paragraphs 3.4, 3.5, or 3.6 of this bulletin. The borrower shall

make certain that all defective pairs are corrected, except those

noted as defective by the cable manufacturer in accordance with

the marking provisions of the applicable cable and wire

specifications. All defective pairs that are not corrected shall

be reported in writing with details of the corrective measures

attempted.

3.3 DC Insulation Resistance (IR) Measurement:

3.3.1 IR measurements shall be made on completed lengths of

insulated cable and wire plant.

3.3.2 Method of Measurement:

3.3.2.1 The IR measurement shall be made between each conductor

and all other conductors, sheath, shield and/or shield/armor,

and/or support wire electrically connected together and to the

main distributing frame (MDF) ground. The measurement shall be

made from the central office with the entire length of the cable

under test and, where used with all protectors and load coils

connected. For COs containing solid state arresters, the solid

state arresters shall be removed before making the IR

measurements. Field mounted voice frequency repeaters, where

used, may be left connected for the IR test but all carrier

frequency equipment, including carrier repeaters and terminals,

shall be disconnected. Pairs used to feed power remote from the
Bulletin 1753F-201(PC-4)

Page 22

CO shall have the power disconnected and the tip and ring

conductors shall be opened before making IR tests. All

conductors shall be opened at the far end of the cable being

measured.

3.3.2.2 IR tests are normally made from the MDF with all CO

equipment disconnected at the MDF, but this test may be made on

new cables at field locations before they are spliced to existing

cables. The method of measurement shall be as shown in Figure 3.

3.3.2.3 If the IR of the conductor cannot be measured because of

breakdown of lightning arresters by the test voltage, the

arrester units shall be removed and the conductor IR retested.

If the IR then meets the minimum requirements, the conductor will

be considered satisfactory. Immediately following the IR tests,

all arrester units which have been removed shall be reinstalled.

3.3.3 Test Equipment:

3.3.3.1 IR measurements shall be made with either an insulation

resistance test set or a direct current (dc) bridge type

megohmmeter.

3.3.3.2 The IR test set shall have an output voltage not to

exceed 500 volts dc and shall be of the hand cranked or battery

operated type.

3.3.3.3 The dc bridge type megohmmeter, which may be alternating

current (ac) powered, shall have scales and multiplier which make

it possible to accurately read IR from 1 megohm to 1 gigohm. The

voltage applied to the conductors under test shall not exceed

"250 volts dc" when using an instrument having adjustable test

voltage levels. This will help to prevent breakdown of lightning

arresters.

3.3.4 Applicable Results:

3.3.4.1 For all new insulated cable or wire facilities, the

expected IR levels are normally greater than 1,000 to 2,000

megohm-mile (1,609 to 3,218 megohm-km). A value of 500 megohmmile (805 megohm-km) at 68°F (20°C) shall be the minimum

acceptable value of IR. IR varies inversely with the length and

the temperature.

3.3.4.2 The megohm-mile (megohm-km) value for a conductor may be

computed by multiplying the actual scale reading in megohms on

the test set by the length in miles (km) of the conductor under

test.

3.3.4.3 The objective insulation resistance may be determined by

dividing 500 by the length in miles (805 by the length in km) of

the cable or wire conductor being tested. The resulting value

shall be the minimum acceptable meter scale reading in megohms.
Bulletin 1753F-201(PC-4)

Page 23

3.3.4.4 Due to the differences between various insulating

materials and filling compounds used in manufacturing cable or

wire, it is impractical to provide simple factors to predict the

magnitude of variation in insulation resistance due to

temperature. The variation can, however, be substantial for wide

excursions in temperature from the ambient temperature of 68°F

(20°C).

3.3.4.5 Borrowers should be certain that tip and ring IR

measurements of each pair are approximately the same. Borrowers

should also be certain that IR measurements are similar for cable

or wire sections of similar length and cable or wire type. If

some pairs measure significantly lower, borrowers should attempt

to improve these pairs in accordance with cable manufacturer’s

recommendations. (Note: Only the megohm-mile (megohm-km)

requirement shall be cause for rejection, not individual

measurement differences.)

3.3.5 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format I, Outside Plant Acceptance

Tests - Subscriber Loops, or Format II, Outside Plant Acceptance

Tests - Trunk Circuits, in Paragraph 7 of this bulletin or

formats specified in the applicable construction contract may be

used.

3.3.6 Probable Causes for Nonconformance:

3.3.6.1 When an IR measurement is below 500 megohm-mile (805

megohm-km), the cable or wire temperature at the time of testing

must then be taken into consideration. If this temperature is

well above 68°F (20°C), the measurement shall be disregarded and

the cable or wire shall be remeasured at a time when the

temperature is approximately 68°F (20°C). If the result is then

500 megohm-mile (805 megohm-km) or greater, the cable or wire

shall be considered satisfactory.

3.3.6.2 Should the cable or wire fail to meet the 500 megohmmile (805 megohm-km) requirement when the temperature is known to

be approximately 68°F (20°C) there is not yet justification for

rejection of the cable or wire. Protectors, lightning arresters,

etc., may be a source of low insulation resistance. These

devices shall be removed from the cable or wire and the cable or

wire IR measurement shall be repeated. If the result is

acceptable, the cable or wire shall be considered acceptable.

The removed devices which caused the low insulation resistance

value shall be identified and replaced, if found defective.

3.3.6.3 When the cable or wire alone is still found to be below

the 500 megohm-mile (805 megohm-km) requirement after completing

the steps in Paragraph 3.3.6.1 and/or Paragraph 3.3.6.2 of this

bulletin, the test shall be repeated to measure the cable or wire

in sections to isolate the piece(s) of cable or wire responsible.

The cable or wire section(s) that is found to be below the 500
Bulletin 1753F-201(PC-4)

Page 24

megohm-mile (805 megohm-km) requirement shall be either repaired

in accordance with the cable or wire manufacturer's recommended

procedure or shall be replaced as directed by the borrower.

3.4 DC Loop Resistance and DC Resistance Unbalance Measurement:

3.4.1 When specified by the borrower, dc loop resistance and dc

resistance unbalance measurements shall be made on all cable

pairs used as trunk circuits. The dc loop resistance and dc

resistance unbalance measurements shall be made between CO

locations. Measurements shall include all components of the

cable path.

3.4.2 Dc loop resistance and dc resistance unbalance

measurements shall be made on all cable pairs used as subscriber

loop circuits when:

a. Specified by the borrower;

b. A large number of long loops terminate at one location

(similar to trunk circuits); or

c. Circuit balance is less than 60 dB when computed from

noise measurements as described in Paragraph 3.5 of

this bulletin.

3.4.3 Dc resistance unbalance is controlled to the maximum

possible degree by the cable specification. Allowable random

unbalance is specified between tip and ring conductors within

each reel. Further random patterns should occur when the cable

conductor size changes. Cable meeting the unbalance requirements

of the cable specification may under some conditions result in of

the cable specification may under some conditions result in

unacceptable noise levels as discussed in Paragraph 3.4.6.3 of

this bulletin.

3.4.4 Method of Measurement: The method of measurement shall be

as detailed in Figures 4 and 5.

3.4.5 Test Equipment: The test equipment is shown in

Figures 4 and 5.

3.4.6 Applicable Results:

3.4.6.1 The measured dc loop resistance shall be within ± 5% of

the calculated dc loop resistance when corrected for temperature.

3.4.6.2 The calculated dc loop resistance is computed as

follows:

3.4.6.2.1 Multiply the length of each different gauge by the

applicable resistance per unit length as shown in Table 3 as

follows:
Bulletin 1753F-201(PC-4)

Page 25

Table 3 - DC Loop Resistance @ 68°F (20°C)

Loop Resistance

American Wire Gauge (AWG) ohms/1000 ft ohms/km

19 16.1 52.8

22 32.4 106.3

24 51.9 170.3

26 83.3 273.3

3.4.6.2.2 Add the individual resistances for each gauge to give

the total calculated dc loop resistance at a temperature of 68°F

(20°C).

3.4.6.2.3 Correct the total calculated dc loop resistance at the

temperature of 68°F (20°C) to the measurement temperature by the

following formulae:

Rt = R68 x [1 + 0.0022 x (t - 68)] for English Units

Rt = R20 x [1 + 0.0040 x (t - 20)] for Metric Units

Where:

Rt = Loop resistance at the measurement temperature

in ohms.

R68 = Loop resistance at a temperature of 68°F

in ohms.

R20 = Loop resistance at a temperature of 20°C

in ohms.

t = Measurement temperature in °F or (°C).

3.4.6.2.4 Compare the calculated dc loop resistance at the

measurement temperature to the measured dc loop resistance to

determine compliance with the requirement specified in Paragraph

3.4.6.1 of this bulletin.

3.4.6.3 Resistance varies directly with temperature change. For

copper conductor cables, the dc resistance changes by ± 1% for

every ± 5°F (2.8°C) change in temperature from 68°F (20°C).

3.4.6.4 The dc resistance unbalance between the individual

conductors of a pair shall not exceed that value which will

result in a circuit balance of less than 60 dB when computed from

noise measurements as described in Paragraph 3.5 of this

bulletin. It is impractical to establish a precise limit for

overall circuit dc resistance unbalance due to the factors

controlling its contribution to circuit noise. These factors

include location of the resistance unbalance in relation to a low

impedance path to ground (close to the central office) and the

magnitude of unbalance in short lengths of cable making up the
Bulletin 1753F-201(PC-4)

Page 26

total circuit length. The objective is to obtain the minimum

unbalance throughout the entire circuit when it is ascertained

through noise measurements that dc resistance unbalance may be

contributing to poor cable balance.

3.4.6.5 Pairs with poor noise balance may be improved by

reversing tip and ring conductors of pairs at cable splices.

Where dc resistance unbalances are systematic over the total

trunk circuit or loop circuit length, tip and ring reversals may

be made at frequent intervals. Where the unbalances are

concentrated in a shorter section of cable, only one tip and ring

reversal should be required. Concentrated dc resistance

unbalance produces maximum circuit noise when located adjacent to

the central office. Concentrated dc resistance unbalance will

contribute to overall circuit noise at a point approximately twothirds (2/3) of the distance to the subscriber. All deliberate

tip and ring reversals shall be tagged and identified to prevent

plant personnel from removing the reversals when resplicing these

connections in the future. The number of tip and ring reversals

shall be held to a minimum.

3.4.6.6 A systematic dc resistance unbalance can sometimes be

accompanied by other cable parameters that are marginal. Among

these are pair-to-pair capacitance unbalance, capacitance

unbalance-to-ground, and 150 kilohertz (kHz) crosstalk loss.

Engineering judgment has to be applied in each case. Rejection

of cable for excessive dc resistance unbalance shall only apply

to a single reel length, or shorter.

3.4.7 Data Record: The measurement data for dc loop resistance

and dc resistance unbalance shall be recorded. Suggested formats

similar to Format I for subscriber loops and Format II for trunk

circuits in Paragraph 7 of this bulletin or formats specified in

the applicable construction contract may be used.

3.4.8 Probable Causes for Nonconformance: Dc loop resistance

and dc resistance unbalance are usually the result of the

resistance of individual conductors used in the manufacture of

the cable. Resistance unbalance can be worsened by defective

splicing of the conductors (splicing connectors, improper

crimping tool, etc.).

3.5 Subscriber Loop Measurement (Loop Checking):

3.5.1 When specified by the borrower, insertion loss and noise

measurements shall be performed on subscriber loops after

connection of a line circuit to the loop by the one person method

using loop checking equipment from the customer access location.

For this method, the central office should be equipped with a 900

ohm plus two microfarad quiet termination and a milliwatt

generator having the required test frequencies; or a portable

milliwatt generator having the desired frequencies may be used,

especially, where several small offices are involved.
Bulletin 1753F-201(PC-4)

Page 27

3.5.2 At a minimum, insertion loss and frequency response of

subscriber loop plant shall be measured at 1,000, 1,700, 2,300,

and 2,800 Hertz (Hz). When additional testing frequencies are

desired, the additional frequencies shall be specified in the

applicable construction contract.

3.5.3 Measurements of insertion loss and noise shall be made on

five percent or more of the pairs. A minimum of five pairs shall

be tested on each route. Pairs shall be selected on a random

basis with greater consideration in the selection given to the

longer loops. Consideration shall be given to measuring a large

percentage, up to 100 percent, of all loops.

3.5.4 Method of Measurement:

3.5.4.1 Insertion Loss: The step-by-step measurement procedure

shall be as shown in Figure 6. The output level of the milliwatt

generator tones shall be determined prior to leaving the CO.

This shall be accomplished by dialing the milliwatt generator

number from a spare line at the MDF and measuring with the same

equipment to be used in the tests at customer access locations.

The output levels shall be recorded for reference later.

Insertion loss measurements shall be made across the tip and ring

terminals of the pair under test.

3.5.4.2 Noise: The step-by-step measurement procedure shall be

as shown in Figure 7. Prior to leaving the CO for testing, dial

the 900 ohm plus two microfarad quiet termination from a spare

pair and measure the termination to determine that it actually is

quiet. Circuit noise (noise-metallic) shall be measured at the

customer access location across the tip and ring terminals of the

pair under test. Power influence (direct reading with loop

checking equipment) shall be measured at the customer access

location from tip and ring conductors-to-ground(this connection

is completed via the test unit). The power influence measurement

includes the entire talking connection from the quiet termination

to the customer. (That is, the power influence measurement

includes all the CO equipment which normally makes up the

connection.)

3.5.5 Test Equipment:

3.5.5.1 Loop checking equipment which is available from several

manufacturers may be used for these measurements. The equipment

should have the capability of measuring loop current, insertion

loss, circuit noise (NM) and power influence (PI). The test

equipment manufacturer's operating instructions shall be

followed.

3.5.5.2 There should be no measurable transmission loss when

testing through loop extenders.
Bulletin 1753F-201(PC-4)

Page 28

3.5.6 Applicable Results:

3.5.6.1 Insertion Loss:

3.5.6.1.1 For D66 loaded cables (a specific loading scheme using

a 66 millihenry inductor spaced nominally at 4,500 ft [1,371 m]

intervals) measured at a point one-half section length beyond the

last load point, the measured nonrepeatered insertion loss shall

be within ± 10% at 1000, 1700, 2300, and 2800 Hz, ± 15% at 3400

Hz and ± 20% at 4000 Hz of the calculated insertion loss at the

same frequencies and temperature.

3.5.6.1.2 For H88 loaded cables (a specific loading scheme using

an 88 millihenry inductor spaced nominally at 6,000 ft [1,829 m]

intervals) measured at a point one-half section length beyond the

last load point, the measured nonrepeatered insertion loss shall

be within ± 10% at 1000, 1700, and 2300 Hz, ± 15% at 2800 Hz, and

± 20% at 3400 Hz of the calculated insertion loss at the same

frequencies and temperature.

3.5.6.1.3 For nonloaded cables, the measured insertion loss

shall be within ± 10% at 1000, 1700, 2300, and 2800 Hz, ± 15% at

3400 Hz and ± 20% at 4000 Hz of the calculated insertion loss at

the same frequencies and temperature.

3.5.6.1.4 For loaded cables, the calculated loss at each desired

frequency shall be computed as follows:

a. Multiply the length in miles (km) of each different

gauge in the loaded portion of the loop (between the

office and a point one-half load section beyond the

furthest load point) by the applicable decibel (dB)/mile

(dB/km) value shown in Table 4 or 5. This loss

represents the total loss for each gauge in the loaded

portion of the loop;

b. Multiply the length in miles (km) of each different

gauge in the end section or nonloaded portion of the

cable (beyond a point one-half load section beyond the

furthest load point) by the applicable dB/mile (dB/km)

value shown in Table 6. This loss represents the total

loss for each gauge in the nonloaded portion of the

loop; and

c. The total calculated insertion loss is computed by

adding the individual losses determined in Items (a)

and (b) of Paragraph 3.5.6.1.4 of this bulletin.

3.5.6.1.5 For nonloaded cables, the calculated loss at each

desired frequency shall be computed by multiplying the length in

miles (km) of each different gauge by the applicable dB/mile

(dB/km) value shown in Table 6 and then adding the individual
Bulletin 1753F-201(PC-4)

Page 29

losses for each gauge to determine the total calculated insertion

loss for the nonloaded loop.

3.5.6.1.6 The attenuation information in Tables 4, 5, and 6 are

based on a cable temperature of 68°F (20°C). Insertion loss

varies directly with temperature. To convert measured losses for

loaded cables to a different temperature, use the following value

for copper conductors: For each ± 5°F (± 2.8°C) change in the

temperature from 68°F (20°C), change the insertion loss at any

frequency by ± 1%. To convert measured losses for nonloaded

cables to a different temperature, use the following value for

copper conductors: For each ± 10°F (± 5.6°C) change in the

temperature from 68°F (20°C), change the insertion loss at any

frequency by ± 1%. Tables 4, 5, and 6 are as follows:

Table 4 - Frequency Attenuation @ 68°F (20°C)

D66 Loaded Exchange Cables

83 nanofarad (nF)/mile (52 nF/km) (See Note)

Frequency

Attenuation dB/mile (dB/km)

AWG

(Hz) 19 22 24 26

200 0.41 (0.26) 0.67 (0.42) 0.90 (0.56) 1.21 (0.75)

400 0.43 (0.26) 0.77 (0.48) 1.09 (0.68) 1.53 (0.95)

600 0.44 (0.27) 0.80 (0.49) 1.17 (0.73) 1.70 (1.06)

800 0.44 (0.27) 0.81 (0.50) 1.21 (0.75) 1.80 (1.12)

1000 0.44 (0.27) 0.82 (0.51) 1.23 (0.76) 1.86 (1.15)

1200 0.45 (0.28) 0.83 (0.52) 1.24 (0.77) 1.91 (1.19)

1400 0.45 (0.28) 0.83 (0.52) 1.26 (0.78) 1.94 (1.20)

1600 0.45 (0.28) 0.84 (0.52) 1.26 (0.78) 1.96 (1.22)

1800 0.45 (0.28) 0.84 (0.52) 1.27 (0.78) 1.98 (1.23)

2000 0.46 (0.29) 0.85 (0.53) 1.28 (0.79) 1.99 (1.24)

2200 0.46 (0.29) 0.85 (0.53) 1.29 (0.80) 2.01 (1.25)

2400 0.47 (0.29) 0.86 (0.53) 1.30 (0.81) 2.02 (1.26)

2600 0.47 (0.29) 0.87 (0.54) 1.31 (0.81) 2.04 (1.27)

2800 0.48 (0.30) 0.88 (0.55) 1.32 (0.82) 2.07 (1.29)

3000 0.49 (0.30) 0.89 (0.55) 1.34 (0.83) 2.10 (1.30)

3200 0.50 (0.31) 0.91 (0.57) 1.36 (0.84) 2.13 (1.32)

3400 0.52 (0.32) 0.93 (0.58) 1.40 (0.87) 2.19 (1.36)

3600 0.54 (0.34) 0.97 (0.60) 1.45 (0.90) 2.26 (1.40)

3800 0.57 (0.35) 1.02 (0.63) 1.52 (0.94) 2.36 (1.47)

4000 0.62 (0.38) 1.10 (0.68) 1.63 (1.01) 2.53 (1.57)

Note: Between end-section lengths of 2,250 ft (686 m) for D66

loading.
Bulletin 1753F-201(PC-4)

Page 30

Table 5 - Frequency Attenuation @ 68°F (20°C)

H88 Loaded Exchange Cables

83 nF/mile (52 nF/km) (See Note)

Frequency

Attenuation dB/mile (dB/km)

AWG

(Hz) 19 22 24 26

200 0.40 (0.25) 0.66 (0.41) 0.90 (0.56) 1.20 (0.75)

400 0.42 (0.26) 0.76 (0.47) 1.08 (0.67) 1.53 (0.95)

600 0.43 (0.27) 0.79 (0.49) 1.16 (0.72) 1.70 (1.06)

800 0.43 (0.27) 0.80 (0.50) 1.20 (0.75) 1.80 (1.12)

1000 0.43 (0.27) 0.81 (0.50) 1.23 (0.76) 1.86 (1.15)

1200 0.44 (0.27) 0.82 (0.51) 1.24 (0.77) 1.91 (1.19)

1400 0.44 (0.28) 0.82 (0.51) 1.25 (0.78) 1.94 (1.20)

1600 0.44 (0.27) 0.83 (0.52) 1.26 (0.78) 1.97 (1.22)

1800 0.45 (0.28) 0.84 (0.52) 1.28 (0.79) 1.99 (1.24)

2000 0.46 (0.29) 0.85 (0.53) 1.29 (0.80) 2.02 (1.26)

2200 0.47 (0.29) 0.86 (0.53) 1.31 (0.81) 2.06 (1.28)

2400 0.48 (0.30) 0.89 (0.55) 1.34 (0.83) 2.10 (1.30)

2600 0.50 (0.31) 0.92 (0.57) 1.39 (0.86) 2.18 (1.35)

2800 0.53 (0.33) 0.97 (0.60) 1.47 (0.91) 2.29 (1.42)

3000 0.59 (0.37) 1.07 (0.66) 1.60 (0.99) 2.48 (1.54)

3200 0.71 (0.44) 1.26 (0.78) 1.87 (1.16) 2.86 (1.78)

3400 1.14 (0.71) 1.91 (1.19) 2.64 (1.64) 3.71 (2.30)

3600 4.07 (2.53) 4.31 (2.68) 4.65 (2.90) 5.30 (3.29)

3800 6.49 (4.03) 6.57 (4.08) 6.72 (4.18) 7.06 (4.39)

4000 8.22 (5.11) 8.27 (5.14) 8.36 (5.19) 8.58 (5.33)

Note: Between end-section lengths of 3,000 ft (914 m) for H88

loading.
Bulletin 1753F-201(PC-4)

Page 31

Table 6 - Frequency Attenuation @ 68°F (20°C)

Nonloaded Exchange Cables

83 nF/mile (52 nF/km)

Frequency

Attenuation dB/mile (dB/km)

AWG

(Hz) 19 22 24 26

200 0.58 (0.36) 0.82 (0.51) 1.03 (0.64) 1.30 (0.81)

400 0.81 (0.51) 1.15 (0.71) 1.45 (0.90) 1.84 (1.14)

600 0.98 (0.61) 1.41 (0.87) 1.77 (1.10) 2.26 (1.40)

800 1.13 (0.70) 1.62 (1.01) 2.04 (1.27) 2.60 (1.61)

1000 1.25 (0.78) 1.80 (1.12) 2.28 (1.42) 2.90 (1.80)

1200 1.36 (0.84) 1.97 (1.22) 2.50 (1.55) 3.17 (1.97)

1400 1.46 (0.91) 2.12 (1.32) 2.69 (1.67) 3.42 (2.12)

1600 1.55 (0.96) 2.26 (1.40) 2.87 (1.78) 3.65 (2.27)

1800 1.63 (1.01) 2.39 (1.48) 3.04 (1.89) 3.87 (2.40)

2000 1.71 (1.06) 2.51 (1.56) 3.20 (1.99) 4.08 (2.53)

2200 1.78 (1.11) 2.62 (1.63) 3.35 (2.08) 4.27 (2.65)

2400 1.85 (1.15) 2.73 (1.70) 3.49 (2.17) 4.45 (2.76)

2600 1.91 (1.19) 2.83 (1.76) 3.62 (2.25) 4.63 (2.88)

2800 1.97 (1.22) 2.93 (1.82) 3.75 (2.33) 4.80 (2.98)

3000 2.03 (1.26) 3.02 (1.88) 3.88 (2.41) 4.96 (3.08)

3200 2.08 (1.29) 3.11 (1.93) 4.00 (2.48) 5.12 (3.18)

3400 2.13 (1.32) 3.19 (1.98) 4.11 (2.55) 5.27 (3.27)

3600 2.18 (1.35) 3.28 (2.04) 4.22 (2.62) 5.41 (3.36)

3800 2.22 (1.38) 3.36 (2.09) 4.33 (2.69) 5.55 (3.45)

4000 2.27 (1.41) 3.43 (2.13) 4.43 (2.75) 5.69 (3.53)

3.5.6.1.7 For loaded subscriber loops, the 1 kHz loss shall be

approximately 0.45 dB per 100 ohms of measured dc loop

resistance. This loss shall be the measured loss less the net

gain of any voice frequency repeaters in the circuit. Testing

shall also be conducted to verify that the loss increases

gradually as the frequency increases. The loss on H88 loaded

loops should be down only slightly at 2.8 kHz but drop rapidly

above 2.8 kHz. The loss on D66 loaded loops shall be fairly

constant to about 3.4 kHz and there shall be good response at 4.0

kHz. When voice frequency repeaters are in the circuit there

will be some frequency weighting in the build-out network and the

loss at the higher frequencies will be greater than for

nonrepeatered loops.

3.5.6.1.8 For nonloaded subscriber loops, the 1 kHz loss shall

be approximately 0.9 dB per 100 ohms of measured dc loop

resistance. Testing shall also be conducted to verify that the

loss is approximately a straight line function with no abrupt

changes. The 3 kHz loss should be approximately 70% higher than

the 1 kHz loss.

3.5.6.2 Noise: The principal objective related to circuit noise

(noise-metallic) and the acceptance of new plant is that circuit

noise levels be 20 dBrnc or less [decibels above reference noise,

C-message weighted (a weighting derived from listening tests, to
Bulletin 1753F-201(PC-4)

Page 32

indicate the relative annoyance or speech impairment by an

interfering signal of frequency (f) as heard through a "500-type"

telephone set)]. For most new, properly installed, plant

construction, circuit noise will usually be considerably less

than 20 dBrnc unless there are unusually long sections of

telephone plant in parallel with electric power facilities and/or

power influence of paralleling electric facilities is abnormally

high. When circuit noise is 20 dBrnc or less, the loop plant

shall be considered acceptable. When measured circuit noise is

greater than 20 dBrnc, loop plant shall still be considered

acceptable providing circuit balance (power influence reading

minus circuit noise readings) is 60 dB or greater and power

influence readings are 85 dBrnc or greater. When circuit noise

is greater than 20 dBrnc and circuit balance is less than 60 dB

and/or power influence is less than 85 dBrnc, loop plant shall

not be considered acceptable and the loop plant shall be remedied

to make circuit balance equal to or greater than 60 dB.

3.5.7 Data Record: Measurement data shall be recorded. A

suggested format similar to Format I for subscriber loops in

Paragraph 7 of this bulletin or a format specified in the

applicable construction contract may be used.

3.5.8 Probable Causes for Nonconformance:

3.5.8.1 Insertion Loss: Some of the more common causes for

failing to obtain the desired results may be due to reversed load

coil windings, missing load coils, bridge taps between load

coils, load coil spacing irregularities, excessive end sections,

cables having high or low mutual capacitance, load coils having

the wrong inductance, load coils inadvertently installed in

nonloaded loops, moisture or water in cable, split pairs, and

improperly spliced connections. The above factors can occur

singularly or in combination. Experience to date indicates that

the most common problems are missing load coils, reversed load

coil windings or bridge taps.

3.5.8.2 Noise: Some of the common causes for failing to obtain

the desired results may be due to high power influence from

paralleling electrical power systems, poor telephone circuit

balance, discontinuous cable shields, inadequate bonding and

grounding of cable shields, high capacitance unbalance-to-ground

of the cable pairs, high dc loop resistance unbalance, dc loop

current less than 20 milliamperes, etc. The above factors can

occur singularly or in combination. See TE&CM Section 451,

Telephone Noise Measurement and Mitigation, for steps to be taken

in reducing telecommunications line noise.
Bulletin 1753F-201(PC-4)

Page 33

3.6 One-Person Open Circuit Measurement (Subscriber Loops):

3.6.1 When specified by the borrower, open circuit measurements

shall be made on all loaded and nonloaded subscriber loops upon

completion of the cable work to verify that the plant is free

from major impedance irregularities.

3.6.2 For loaded loops, open circuit measurements shall be made

using one of the following methods:

a. Impedance or pulse return pattern, with cable pair trace

compared to that of an artificial line of the same

length and gauge. For best results, a level tracer or

fault locator with dual trace capability is required;

b. Return loss using a level tracer, with cable pair

compared to an artificial line of the same length and

gauge connected in lieu of a Precision Balance Network

(PBN). This method can be made with level tracers

having only single trace capability; or

c. Open circuit structural return loss using a level

tracer. This method can be made with level tracer

having only single trace capability.

3.6.3 Of the three methods suggested for loaded loops, the

method specified in item (b.) of Paragraph 3.6.2 of this bulletin

is the preferred method because it can yield both qualitative and

quantitative results. The methods specified in items (a.) and

(c.) of Paragraph 3.6.2 of this bulletin can be used as trouble

shooting tools should irregularities be found during testing.

3.6.4 For nonloaded loops, open circuit measurements shall be

made using the method specified in item (a.)of Paragraph 3.6.2 of

this bulletin.

3.6.5 Method of Measurement: Open circuit measurements shall be

made at the CO on each loaded and nonloaded pair across the tip

and ring terminals of the pair under test. All CO equipment

shall be disconnected at the MDF for this test. For loaded loops

containing voice frequency repeaters installed in the CO or field

mounted, the open circuit measurement shall be made after the

repeaters have been disconnected. Where field mounted repeaters

are used, the open circuit measurement shall be made at the

repeater location in both directions.

3.6.5.1 Impedance or Pulse Return Pattern: The step-by-step

measurement procedure using the impedance or pulse return pattern

for loaded and nonloaded loops shall be as shown in Figure 8. An

artificial line of the same makeup as the cable to be tested

shall be set up. The traces of the impedance or pulse return

pattern from the cable pair and the artificial line shall be

compared and should be essentially identical. If the impedance
Bulletin 1753F-201(PC-4)

Page 34

or pulse return traces from the cable pair are different than the

artificial line trace, cable faults are possible. When the cable

pair trace indicates possible defects, the defects should be

identified and located. One method of identifying and locating

defects involves introducing faults into the artificial line

until its trace is identical with the cable trace.

3.6.5.2 Return Loss Balanced to Artificial Line: The step-bystep measurement procedure using the return loss balanced to

artificial line for loaded loops shall be as shown in Figure 9.

An artificial line of the same makeup as the cable to be tested

shall be set up. The artificial line is connected to the

external network terminals of the test set. The cable pair under

test is compared to this standard. When defects are found, they

should be identified and located by introducing faults into the

artificial line. This is more difficult than with the method

referenced in Paragraph 3.6.5.1 of this bulletin since this

measurement is more sensitive to minor faults and only a single

trace is used.

3.6.5.3 Open Circuit Structural Return Loss using Level Tracer:

The step-by-step measurement procedure using the level tracer for

loaded loops shall be as shown in Figure 10. The cable pair is

compared to a PBN.

3.6.6 Test Equipment: Equipment for performing these tests is

shown in Figures 8 through 10. For loaded loops, artificial

loaded lines must be of the same gauge and loading scheme as the

line under test. For nonloaded loops, artificial nonloaded lines

must be of the same gauge as the line under test. Artificial

lines should be arranged using switches or other quick connect

arrangements to speed testing and troubleshooting.

3.6.7 Applicable Results:

3.6.7.1 For loaded and nonloaded loops, the two traces in the

pulse return pattern or impedance method (Paragraph 3.6.5.1 of

this bulletin) shall be essentially identical. The degree of

comparison required of the two traces is to be determined by

experience.

3.6.7.2 For loaded loops, results for return loss measurements

using a level tracer, with artificial line, in lieu of a PBN

(Paragraph 3.6.5.2 of this bulletin) shall meet the following

requirements:

a. For D66 and H88 loaded cables the structural return

loss (SRL) values shall range between 28 and 39 dB,

respectively, at the critical frequency of structural

return loss (CFSRL) within the pass band of the loading

system being used. The minimum SRL value for uniform

gauge shall be 25 dB CFSRL. These SRL values apply for

loaded cables of uniform gauge for the entire length of
Bulletin 1753F-201(PC-4)

Page 35

the subscriber loop circuit. Subscriber loop circuits

shall meet the loading spacing deviations and the cable

mutual capacitance requirements in the applicable RUS

cable specifications;

b. For mixed gauge loaded cables the SRL values shall be

25 and 27 dB CFSRL, respectively, and the minimum SRL

value shall be 22 dB CFSRL; and

c. The two traces in the pulse return pattern should be

essentially identical. The degree of comparison

required of the two traces is determined by experience.

3.6.7.3 For loaded loops, the results of open circuit structural

return loss measurements using a level tracer (Paragraph 3.5.5.3

of this bulletin) shall meet the following requirements. For D66

and H88 loaded cables with uniform or mixed gauges, the worst

value allowed for measured open circuit structural return loss

between 1,000 - 3,500 Hz and 1,000 - 3,000 Hz, respectively,

shall be approximately 0.9 dB (round trip) for each 100 ohms

outside plant dc loop resistance including the resistance of the

load coils. The value of 0.9 dB per 100 ohms for the round trip

loss remains reasonably accurate as long as:

a. The subscriber end section of the loaded pair under

test is approximately 2,250 ft (685 m) for D66 loading

or 3,000 ft (914 m) for H88 loading in length; and

b. The one-way 1,000 Hz loss does not exceed 10 dB.

3.6.7.4 For loaded loops, the measured value of open circuit

structural return loss can only be as accurate as the degree to

which the dc loop resistance of the loaded pair under test is

known. Most accurate results shall be obtained when the dc loop

resistance is known by actual measurements as described in

Paragraph 3.4 of this bulletin. Furthermore, where the dc loop

resistance is measured at the same time as the open circuit

structural return loss, no correction for temperature is needed

because the loss is directly proportional to the loop resistance.

Where it is not practical to measure the dc loop resistance, it

shall be calculated and corrected for temperature as specified in

Paragraph 3.4.6.2 of this bulletin. When measuring existing

plant, care shall be taken to verify the accuracy of the records,

if they are used for the calculation of the dc loop resistance.

For buried plant, the temperature correction shall be based at

the normal depth of the cable in the ground. (Temperature can be

measured by boring a hole to cable depth with a ground rod,

placing a thermometer in the ground at the cable depth, and

taking and averaging several readings during the course of the

resistance measurements.) For aerial cable it shall be based on

the temperature inside the cable sheath.
Bulletin 1753F-201(PC-4)

Page 36

3.6.7.5 For loaded loops, the best correlation between the

measured and the expected results shall be obtained when the

cable is of one gauge, one size, and the far end section is

approximately 2,250 ft (685 m) for D66 loading or 3,000 ft

(914 m) for H88 loading. Mixing gauges and cable sizes will

result in undesirable small reflections whose frequency

characteristics and magnitude cannot be accurately predicted. In

subscriber loop applications, cable gauge may be somewhat uniform

but the cable pair size most likely will not be uniform as cable

pair sizes taper off toward the customer access location and a

downward adjustment of 1 dB of the allowed value shall be

acceptable. "Long" end sections (as defined in TE&CM Section

424, "Guideline for Telecommunications Subscriber Loop Plant")

lower the expected value, a further downward adjustment of 3 dB

in the allowed value shall be acceptable.

3.6.7.6 For loaded loops, the limiting factor when making open

circuit structural return loss measurements is when the 1,000 Hz

one-way loss of the loaded cable pair under test becomes 10 dB or

greater; it becomes difficult to detect the presence of

irregularities beyond the 10 dB point on the loop. To overcome

this difficulty, loaded loops having a one-way loss at 1,000 Hz

greater than 10 dB shall be opened at some convenient point (such

as a pedestal or ready access enclosure) and loss measurements at

the individual portions measuring less than 10 dB one-way shall

be made separately. When field mounted voice frequency repeaters

are used, the measurement shall be made at the repeater location

in both directions.

3.6.8 Data Record:

3.6.8.1 When performing a pulse return pattern or impedance open

circuit measurement on loaded and nonloaded loops, a "check mark"

indicating that the pair tests good or an "X" indicating that the

pair does not test good shall be recorded in the SRL column. A

suggested format similar to Format I for subscriber loops in

Paragraph 7 of this bulletin or a format specified in the

applicable construction contract may be used.

3.6.8.2 When performing open circuit return loss measurements

using the return loss balanced to an artificial line or return

loss using a level tracer on loaded loops, the value of the

poorest (lowest numerical value) SRL and its frequency in the

proper column between 1,000 and 3,500 Hz for D66 loading or

between 1,000 and 3,000 Hz for H88 loading shall be recorded. A

suggested format similar to Format I for subscriber loops in

Paragraph 7 of this bulletin or a format specified in the

applicable construction contract may be used.

3.6.9 Probable Causes for Nonconformance: Some of the more

common causes for failing to obtain the desired results may be

due to reversed load coil windings, missing load coils, bridge

taps between load coils, load coil spacing irregularities,
Bulletin 1753F-201(PC-4)

Page 37

excessive end sections, cables having high or low mutual

capacitance, load coils inadvertently installed in nonloaded

loops, moisture or water in the cable, load coils having the

wrong inductance, split pairs, and improperly spliced connectors.

The above can occur singularly or in combination. Experience to

date indicates that the most common problems are missing load

coils, reversed load coil windings or bridge taps.

3.7 Cable Insertion Loss Measurement (Carrier Frequencies):

3.7.1 When specified by the borrower, carrier frequency

insertion loss measurements shall be made on cable pairs used for

T1, T1C, and/or station carrier systems. Carrier frequency

insertion loss shall be made on a minimum of three pairs. Select

at least one pair near the outside of the core unit layup. If

the three measured pairs are within 10% of the calculated loss in

dB corrected for temperature, no further testing is necessary.

If any of the measured pairs of a section are not within 10% of

the calculated loss in dB, all pairs in that section used for

carrier transmission shall be measured.

3.7.2 Method of Measurement: The step-by-step method of

measurement shall be as shown in Figure 11.

3.7.3 Test Equipment: The test equipment is shown in Figure 11.

3.7.4 Applicable Results:

3.7.4.1 The highest frequency to be measured is determined by

the type of carrier system. For T1 type carrier, the highest

frequency is normally 772 kHz. For T1C type carrier, the highest

frequency is normally 1576 kHz. The highest frequency to be

measured for station carrier is 140 kHz.

3.7.4.2 The measured insertion loss of the cable shall be within

± 10% of the calculated loss in dB when the loss is corrected for

temperature.

3.7.4.3 The calculated insertion loss is computed as follows:

a. Multiply the length of each different gauge by the

applicable dB per unit length as shown in Table 7 or 8:
Bulletin 1753F-201(PC-4)

Page 38

Table 7 - Cable Attenuation @ 68°F (20°C)

Filled Cables - Solid Insulation

Frequency

Attenuation dB/mile (dB/km)

Gauge (AWG)

(kHz) 19 22 24 26

10 2.8 (1.7) 4.8 (2.9) 6.4 (3.9) 8.5 (5.3)

20 3.2 (2.0) 5.8 (3.6) 8.2 (5.1) 11.2 (6.9)

40 3.6 (2.2) 6.5 (4.0) 9.6 (6.0) 13.9 (8.6)

60

80

4.0 (2.5)

4.5 (2.8)

6.9 (4.2)

7.3 (4.5)

10.3 (6.4)

10.7 (6.6)

15.2 (9.4)

16.0 (9.9)

100 4.9 (3.0) 7.7 (4.7) 11.1 (6.8) 16.5 (10.2)

112 5.2 (3.2) 8.0 (4.9) 11.3 (7.0) 16.8 (10.5)

120 5.4 (3.3) 8.1 (5.0) 11.5 (7.1) 17.0 (10.6)

140 5.8 (3.6) 8.6 (5.3) 11.9 (7.4) 17.4 (10.8)

160

180

6.2 (3.8)

6.6 (4.1)

9.0 (5.6)

9.5 (5.9)

12.3 (7.6)

12.7 (7.9)

17.8 (11.1)

18.2 (11.3)

200 7.0 (4.3) 10.0 (6.2) 13.2 (8.2) 18.6 (11.5)

300 8.7 (5.4) 12.2 (7.5) 15.4 (9.6) 20.6 (12.8)

400 10.0 (6.2) 14.1 (8.8) 17.7 (11.0) 22.9 (14.2)

500 11.2 (6.9) 15.9 (9.8) 19.8 (12.3) 25.2 (15.6)

600

700

772

800

900

12.2 (7.5)

13.2 (8.2)

13.8 (8.5)

14.2 (8.8)

14.8 (9.2)

17.5 (10.9)

19.0 (11.8)

19.9 (12.4)

20.1 (12.5)

21.6 (13.4)

21.8 (13.6)

23.6 (14.7)

24.8 (15.4)

27.4 (17.1)

29.0 (18.0)

27.4 (17.0)

29.6 (18.4)

31.4 (19.5)

31.7 (19.7)

33.8 (21.0)

1000 15.8 (9.8) 22.7 (14.1) 31.1 (19.3) 35.9 (22.3)

1100 16.4 (10.2) 23.8 (14.8) 32.7 (20.3) 38.0 (23.6)

1200 17.4 (10.8) 24.8 (15.4) 34.3 (21.3) 40.0 (24.9)

1300 17.9 (11.1) 25.9 (16.1) 35.4 (22.0) 41.7 (25.9)

1400 19.0 (11.8) 26.9 (16.7) 37.0 (23.0) 43.3 (26.9)

1500

1576

19.5 (12.1)

20.1 (12.4)

28.0 (17.4)

29.0 (18.0)

38.0 (23.6)

39.0 (24.3)

44.3 (27.6)

44.4 (28.2)
Bulletin 1753F-201(PC-4)

Page 39

Table 8 - Cable Attenuation @ 68°F (20°C)

Filled Cables - Expanded Insulation

Frequency

Attenuation dB/mile (dB/km)

Gauge (AWG)

(kHz) 19 22 24 26

10 3.0 (1.8) 4.9 (3.0) 6.5 (4.0) 8.6 (5.3)

20 3.5 (2.1) 6.0 (4.1) 8.5 (5.2) 11.5 (7.1)

40 4.0 (2.5) 7.0 (4.3) 10.2 (6.3) 14.4 (8.9)

60

80

4.5 (2.8)

5.2 (3.3)

7.5 (4.6)

7.9 (4.9)

11.1 (6.8)

11.3 (6.9)

16.0 (9.9)

16.2 (10.1)

100 5.8 (3.6) 8.4 (5.2) 11.6 (7.2) 16.4 (10.2)

112 6.0 (3.8) 8.8 (5.4) 11.9 (7.4) 16.6 (10.3)

120 6.2 (3.9) 9.0 (5.6) 12.1 (7.5) 16.9 (10.5)

140 6.6 (4.1) 9.5 (5.9) 12.7 (7.9) 17.2 (10.7)

160

180

6.9 (4.3)

7.4 (4.6)

10.0 (6.2)

10.6 (6.6)

13.2 (8.2)

13.7 (8.5)

17.4 (10.8)

17.9 (11.1)

200 7.9 (4.9) 11.1 (6.9) 14.2 (8.8) 18.5 (11.5)

300 9.5 (5.9) 13.2 (8.2) 16.8 (10.5) 21.6 (13.4)

400 11.1 (6.9) 15.3 (9.5) 19.5 (12.1) 24.3 (15.1)

500 12.1 (7.5) 17.9 (11.1) 22.2 (13.8) 27.4 (17.1)

600

700

772

800

900

13.7 (8.5)

14.8 (9.2)

15.3 (9.5)

15.8 (9.8)

17.0 (10.5)

19.5 (12.1)

21.1 (13.1)

21.6 (13.4)

22.2 (13.8)

23.8 (14.8)

24.3 (15.1)

26.4 (16.4)

27.4 (17.1)

28.0 (17.4)

29.6 (18.4)

29.6 (18.4)

32.2 (20.0)

33.8 (21.0)

34.4 (21.3)

36.4 (22.6)

1000 17.4 (10.8) 24.8 (15.4) 31.1 (19.3) 38.5 (23.9)

1100 17.9 (11.1) 26.4 (16.4) 33.3 (20.7) 40.6 (25.3)

1200 19.0 (11.8) 27.4 (17.1) 34.3 (21.3) 42.2 (26.2)

1300 19.5 (12.1) 28.5 (17.7) 35.9 (22.3) 43.8 (27.2)

1400 20.1 (12.5) 29.6 (18.4) 37.0 (23.0) 45.9 (28.5)

1500

1576

20.6 (12.8)

21.6 (13.4)

30.6 (19.0)

31.1 (19.3)

38.5 (23.9)

39.1 (24.3)

47.5 (29.5)

48.6 (30.2)

b. Add the individual losses for each gauge to give the

total calculated insertion loss at a temperature of

68°F (20°C);

c. Correct the total calculated insertion loss at the

temperature of 68°F (20°C) to the measurement

temperature by the following formulae:

At = A68 x [1 + 0.0012 x (t - 68)] for English Units

At = A20 x [1 + 0.0022 x (t - 20)] for Metric Units
Bulletin 1753F-201(PC-4)

Page 40

Where:

At = Insertion loss at the measurement temperature

in dB.

A68 = Insertion loss at a temperature of 68°F in dB.

A20 = Insertion loss at a temperature of 20°C in dB.

t = Measurement temperature in °F or (°C); and

d. Compare the calculated insertion loss at the measurement

temperature to the measured insertion loss to determine

compliance with the requirement specified in Paragraph

3.7.4.2 of this bulletin. (Note: Attenuation varies

directly with temperature. For each ± 10°F (5.6°C)

change in temperature increase or decrease the

attenuation by ± 1%.)

3.7.4.4 If the measured value exceeds the ± 10% allowable

variation, the cause shall be determined and corrective action

shall be taken to remedy the problem.

3.7.5 Data Record: Results of carrier frequency insertion loss

measurements for station, T1, and/or T1C type carrier shall be

recorded. Suggested formats similar to Format III, Outside Plant

Acceptance Tests - T1 or T1C Carrier Pairs, and Format IV,

Outside Plant Acceptance Tests - Station Carrier Pairs, in

Paragraph 7 of this bulletin or formats specified in the

applicable construction contract may be used.

3.7.6 Probable Causes for Nonconformance: If the measured loss

is low, the cable records are likely to be in error. If the

measured loss is high, there may be bridge taps, load coils or

voice frequency build-out capacitors connected to the cable pairs

or the cable records may be in error. Figures 12 and 13 are

examples that show the effects of bridge taps and load coils in

the carrier path.

4. FIBER OPTIC CABLE TELECOMMUNICATIONS PLANT MEASUREMENTS

4.1 Armor Continuity:

4.1.1 Tests and measurements shall be made to ensure that the

armor of fiber optic cables is continuous. There are two areas

of concern. The first is armor bonding within a splice and the

second is armor continuity between splices.

4.1.2 Measurement techniques outlined here for verification of

armor continuity are applicable to buried fiber optic cable

plant. Measurements of armor continuity between splices in

aerial, armored, fiber optic cable should be made prior to
Bulletin 1753F-201(PC-4)

Page 41

completion of splicing. Conclusive results cannot be obtained on

aerial plant after all bonds have been completed to the

supporting strand, multigrounded neutral, etc.

4.1.3 Method of Measurement: Armor continuity within splices

shall be measured with a cable shield splice continuity test set.

The step-by-step measurement procedure outlined in the

manufacturer's operating instructions for the specific test

equipment being used shall be followed.

4.1.4 Test Equipment: A cable shield splice continuity tester

shall be used to measure armor continuity within splices.

4.1.5 Applicable Results: When utilizing shield continuity

testers to measure armor continuity within splices, refer to the

manufacturer's published information covering the specific test

equipment to be used and for anticipated results.

4.1.6 Data Record: Measurement data from armor continuity tests

shall be recorded together with anticipated values in an

appropriate format to permit comparison. The recorded data shall

include specific location, cable size, and cable type, if known,

etc.

4.1.7 Probable Causes for Nonconformance: Among probable causes

for nonconformance are broken or damaged armors, bad bonding

harnesses, poorly connected bonding clamps, loose bonding lugs,

etc.

4.2 Fiber Optic Splice Loss Measurement:

4.2.1 After placement of all fiber optic cable plant has been

completed and spliced together to form a continuous optical link

between end termination points, splice loss measurements shall be

performed on all field and central office splice points.

4.2.2 Method of Measurement:

4.2.2.1 Field splice loss measurements shall be made between the

end termination points at 1310 and/or 1550 nanometers for single

mode fibers and in accordance with Figure 14. Two splice loss

measurements shall be made between the end termination points.

The first measurement shall be from termination point A to

termination point B. The second measurement shall be from

termination point B to termination point A.

4.2.2.2 CO splice loss measurements shall be made at 1310 and/or

1550 nanometers for single mode fibers and in accordance with

Figure 15. Two splice loss measurements shall be made between

the end termination points. The first measurement shall be from

termination point A to termination point B. The second

measurement shall be from termination point B to termination

point A.
Bulletin 1753F-201(PC-4)

Page 42

4.2.3 Test Equipment: The test equipment is shown in Figures 14

and 15. The optical time domain reflectometer (OTDR) used for

the testing should have dual wave length capability.

4.2.4 Applicable Results:

4.2.4.1 The splice loss for each single mode field splice shall

be the bi-directional average of the two OTDR readings. To

calculate the actual splice loss, substitute the OTDR readings

maintaining the sign of the loss (+) or apparent gain (−) into

the following equation:

OTDR Reading OTDR Reading

Actual Splice = From A to B + From B to A

Loss (dB) 2

4.2.4.2 When specified in the applicable construction contract,

the splice loss of each field splice at 1310 and/or 1550

nanometers shall not exceed the limit specified in the contract.

4.2.4.3 When no limit is specified in the applicable

construction contract, the splice loss of each field splice shall

not exceed 0.2 dB at 1310 and/or 1550 nanometers.

4.2.4.4 The splice loss for each single mode CO splice shall be

the bi-directional average of the two OTDR reading. To calculate

actual splice loss, substitute the OTDR reading, maintaining the

sign of the loss (+) or apparent gain (−), into the equation

specified in Paragraph 4.2.4.1 of this bulletin.

4.2.4.5 When specified in the applicable construction contract,

the splice loss of each central office splice at 1310 and/or 1550

nanometers shall not exceed the limit specified in the contract.

4.2.4.6 When no limit is specified in the applicable

construction contract, the splice loss of each central office

splice shall not exceed 1.2 dB at 1310 and/or 1550 nanometers.

4.2.5 Data Record: The measurement data shall be recorded. A

suggested format similar to Format V, Outside Plant Acceptance

Test - Fiber Optic Telecommunications Plant, in Paragraph 7 of

this bulletin or a format specified in the applicable

construction contract may be used.

4.2.6 Probable Causes for Nonconformance: When the results of

the splice loss measurements exceed the specified limits the

following factors should be checked:

a. Proper end preparation of the fibers;

b. End separation between the fiber ends;

c. Lateral misalignment of fiber cores;
Bulletin 1753F-201(PC-4)

Page 43

d. Angular misalignment of fiber cores;

e. Fresnel reflection;

f. Contamination between fiber ends;

g. Core deformation; or

h. Mode-field diameter mismatch.

4.3 End-to-End Attenuation Measurement:

4.3.1 After placement of all fiber optic cable plant has been

completed and spliced together to form a continuous optical link

between end termination points, end-to-end attenuation

measurements shall be performed on each optical fiber within the

cable.

4.3.2 Method of Measurement: For single mode fibers, the endto-end attenuation measurements of each optical fiber at 1310

and/or 1550 nanometers in each direction between end termination

points shall be performed in accordance with Figure 16.

4.3.3 Test Equipment: The test equipment is shown in Figure 16.

4.3.4 Applicable Results: The end-to-end attenuation of each

single mode optical fiber at 1310 and/or 1550 nanometers shall

not exceed the limits specified in the applicable construction

contract.

4.3.5 Data Record: The measurement data shall be recorded. A

suggested format similar to Format V for fiber optic

telecommunications plant in Paragraph 7 of this bulletin or on a

format specified in the applicable construction contract may be

used.

4.3.6 Probable Causes for Nonconformance: Failure of each

optical fiber to meet the end-to-end attenuation limit could be

attributed to the following:

a. Excessive field or central office splice loss;

b. Excessive cable attenuation; or

c. Damage to the fiber optic cable during installation.

4.4 End-to-End Fiber Signature Measurement:

4.4.1 After placement of all fiber optic cable plant has been

completed and spliced together to form a continuous optical link

between end termination points, end-to-end fiber signature

testing shall be performed on each optical fiber within the

cable.
Bulletin 1753F-201(PC-4)

Page 44

4.4.2 Method of Measurement: For single mode fibers, the endto-end fiber signature measurement of each optical fiber in each

direction shall be performed between end termination points at

1310 and/or 1550 nanometers in accordance with Figure 17.

4.4.3 Test Equipment: The test equipment is shown in Figure 17.

4.4.4 Applicable Results: The appearance of each optical fiber

between end termination points.

4.4.5 Data Record: Plot the trace of each optical fiber and

retain as a permanent record for future comparison if needed.

4.4.6 Probable Causes for Nonconformance: None.

5. VOICEBAND DATA TRANSMISSION MEASUREMENTS

5.1 The data transmission measurements listed in this section

shall be used to determine the acceptability of trunk and

nonloaded subscriber loop circuits for data modem transmission.

5.2 Signal-to-C Notched Noise (S/CNN) Measurement:

5.2.1 When specified by the borrower, S/CNN measurements shall

be made on trunk circuits and nonloaded subscriber loops. For

trunk circuits, the measurement shall be made between CO

locations. For nonloaded subscriber loops, the measurement shall

be made from the CO to the station protector of the NID at the

customer's access location.

5.2.2 S/CNN is the logarithmic ratio expressed in dB of a 1,004

Hz holding tone signal compared to the C-message weighted noise

level. S/CNN is one of the most important transmission

parameters affecting the performance of data transmission because

proper modem operation requires low noise relative to received

power level. Since modulated carriers are used in data

communication systems, noise measurements need to be performed

with power on the connection to activate equipment having signallevel-dependent noise sources. For 4 kHz channels, a 1,004 Hz

holding tone is used to activate the signal-dependent equipment

on the channel or connection.

5.2.3 Method of Measurement: The S/CNN measurement shall be

made using a 1,004 Hz holding tone at −13 dBm0 (decibels relative

to one milliwatt, referred to a zero transmission level point)

and performed in accordance with American National Standards

Institute (ANSI) T1.506-1990, American National Standard for

Telecommunications - Network Performance - Transmission

Specifications for Switched Exchange Access Network including

supplement ANSI T1.506a-1992, and American National Standards

Institute/Institute of Electrical and Electronics
Bulletin 1753F-201(PC-4)

Page 45

Engineers(ANSI/IEEE) 743-1984, IEEE Standard Methods and

Equipment for Measuring the Transmission Characteristics of

Analog Voice Frequency Circuits.

5.2.4 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.2.5 Applicable Results: The S/CNN for both trunk and

nonloaded subscriber loop circuits shall not be less than 31 dB.

5.2.6 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI, Voiceband Data

Transmission Tests - Nonloaded Subscriber Loops, and Format VII,

Voiceband Data Transmission Tests - Trunk Circuits, in Paragraph

7 of this bulletin or formats specified in the applicable

construction contract may be used.

5.2.7 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to excessive

harmonic distortion, quantizing noise, phase and amplitude

jitter, and loss in digital pads used for level settings.

5.3 Signal-to-Intermodulation Distortion (S/IMD) Measurement:

5.3.1 When specified by the borrower, S/IMD measurements shall

be made on trunk circuits and nonloaded subscriber loops. For

trunk circuits, the measurement shall be made between CO

locations. For nonloaded subscriber loops, the measurement shall

be made from the CO to the station protector of the NID at the

customer's access location.

5.3.2 S/IMD is a measure of the distortion produced by

extraneous frequency cross products, known as intermodulation

products, when a multi-tone tone signal is applied to a system.

5.3.3 Intermodulation distortion (IMD) is caused by system

nonlinearities acting upon the harmonic frequencies produced from

an input of multiple tones. The products resulting from IMD can

be more damaging than noise in terms of producing data

transmission errors.

5.3.4. IMD is measured as a signal to distortion ratio and is

expressed as the logarithmic ratio in dB of the composite power

of four resulting test frequencies to the total power of specific

higher order distortion products that are produced. The higher

order products are measured at both the 2nd order and 3rd order

and are designated R2 and R3, respectively. The four frequency

testing for IMD is produced with four tones of 857, 863, 1,372,

and 1,388 Hz input at a composite power level of −13 dBm0.

5.3.5 Method of Measurement: The S/IMD measurement shall be

performed in accordance with ANSI T1.506-1990 and ANSI/IEEE

743-1984.
Bulletin 1753F-201(PC-4)

Page 46

5.3.6 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.3.7 Applicable Results: The 2nd order (R2) S/IMD for both

trunk and nonloaded subscriber loop circuits shall not be less

than 40 dB. The 3rd order (R3) S/IMD for both trunk and nonloaded

subscriber loop circuits shall not be less than 40 dB.

5.3.8 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI for nonloaded subscriber

loops and Format VII for trunk circuits in Paragraph 7 of this

bulletin or formats specified in the applicable construction

contract may be used.

5.3.9 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to channel

nonlinearities, such as compression and clipping, which cause

harmonic and intermodulation distortion in a voiceband signal.

5.4 Envelope Delay Distortion (EDD) Measurement:

5.4.1 When specified by the borrower, EDD measurements shall be

made on trunk circuits and nonloaded subscriber loops. For trunk

circuits, the measurement shall be made between CO locations.

For nonloaded subscriber loops, the measurement shall be made

from the CO to the station protector of the NID at the customer's

access location.

5.4.2 EDD is a measure of the linearity or uniformity of the

phase versus frequency characteristics of a transmission

facility. EDD is also known as relative envelope delay (RED).

5.4.3 EDD is specifically defined as the delay relative to the

envelope delay at the reference frequency of 1,704 Hz. EDD is

typically measured at two frequencies, one low and one high in

the voiceband. The low frequency measurement is made at 604 Hz.

The high frequency measurement is made at 2,804 Hz.

5.4.4 Method of Measurement: The EDD measurement shall be

performed in accordance with ANSI T1.506-1990 and ANSI/IEEE

743-1984.

5.4.5 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.4.6 Applicable Results: The EDD for both trunk and nonloaded

subscriber loop circuits at the low frequency of 604 Hz shall not

exceed 1,500 microseconds. The EDD for both trunk and nonloaded

subscriber loop circuits at the high frequency of 2,804 Hz shall

not exceed 1,000 microseconds.

5.4.7 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI for nonloaded subscriber
Bulletin 1753F-201(PC-4)

Page 47

loops and Format VII for trunk circuits in Paragraph 7 of this

bulletin or formats specified in the applicable construction

contract may be used.

5.4.8 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to

nonlinearity of the phase versus frequency characteristic of the

transmission facility. This nonlinear phase versus frequency

characteristic of the transmission facility causes the various

frequency components to travel at different transit times which

results in successively transmitted data pulses to overlap at the

receive end. The overlapping of the pulses at the receive end

results in distortion of the received signal. Excessive EDD on

the transmission facility may be reduced using data modems with

equalization or by conditioning the transmission line.

5.5 Amplitude Jitter (AJ) Measurement:

5.5.1 When specified by the borrower, AJ measurements shall be

made on trunk circuits and nonloaded subscriber loops. For trunk

circuits, the measurement shall be made between CO locations.

For nonloaded subscriber loops, the measurement shall be made

from the CO to the station protector of the NID at the customer's

access location.

5.5.2 AJ is any fluctuation in the peak amplitude value of a

fixed tone signal at 1,004 Hz from its nominal value. AJ is

expressed in peak percent amplitude modulation.

5.5.3 AJ is measured in two separate frequency bands, 4 - 300 Hz

and 20 - 300 Hz. The 4 - 300 Hz band is important for modems

employing echo canceling capabilities. The 20- 300 Hz band is

used for modems that do not employ echo cancelers.

5.5.4 Amplitude modulation can affect the error performance of

voiceband data modems. The measurement of amplitude jitter

indicates the total effect on the amplitude of the holding tone

of incidental amplitude modulation and other sources including

quantizing and message noise, impulse noise, gain hits, phase

jitter, and additive tones such as single-frequency interference.

5.5.5 Method of Measurement: The AJ measurement shall be

performed in accordance with ANSI T1.506-1990 and ANSI/IEEE

743-1984.

5.5.6 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.5.7 Applicable Results: The AJ for both trunk and nonloaded

subscriber loop circuits in the 4 - 300 Hz frequency band shall

not exceed 6%. The AJ for both trunk and nonloaded subscriber

loop circuits in the 20 - 300 Hz frequency band shall not exceed

5%.
Bulletin 1753F-201(PC-4)

Page 48

5.5.8 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI for nonloaded subscriber

loops and Format VII for trunk circuits in Paragraph 7 of this

bulletin or formats specified in the applicable construction

contract may be used.

5.5.9 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to excessive

S/CNN, impulse noise, and phase jitter.

5.6 Phase Jitter (PJ) Measurement:

5.6.1 When specified by the borrower, PJ measurements shall be

made on trunk circuits and nonloaded subscriber loops. For trunk

circuits, the measurement shall be made between CO locations.

For nonloaded subscriber loops, the measurement shall be made

from the CO to the station protector of the NID at the customer's

access location.

5.6.2 PJ is any fluctuation in the zero crossings of a fixed

tone signal (usually 1,004 Hz) from their nominal position in

time within the voiceband. PJ is expressed in terms of either

degrees peak-to-peak (°p-p) or in terms of a Unit Interval (UI).

One UI is equal to 360° p-p.

5.6.3 PJ measurements are typically performed in two nominal

frequency bands. The frequency bands are 20 - 300 Hz band and

either the 2 - 300 Hz band or the 4 - 300 Hz band. The 20 - 300

Hz band is important to all phase-detecting modems. The 4 - 300

Hz band or the 2 - 300 Hz band is important for modems employing

echo canceling capabilities.

5.6.4 Phase jitter can affect the error performance of voiceband

data modems that use phase detection techniques. The measurement

of phase jitter indicates the total effect on the holding tone of

incidental phase modulation and other sources including

quantizing and message noise, impulse noise, phase hits, additive

tones such as single-frequency interference, and digital timing

jitter.

5.6.5 Method of Measurement: The PJ measurement shall be

performed in accordance with ANSI T1.506-1990 and ANSI/IEEE

743-1984.

5.6.6 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.6.7 Applicable Results: The PJ for both trunk and nonloaded

subscriber loop circuits in the 4 - 300 Hz frequency band shall

not exceed 6.5° p-p. The PJ for both trunk and nonloaded

subscriber loop circuits in the 20 - 300 Hz frequency band shall

not exceed 10.0° p-p.
Bulletin 1753F-201(PC-4)

Page 49

5.6.8 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI for nonloaded subscriber

loops and Format VII for trunk circuits in Paragraph 7 of this

bulletin or formats specified in the applicable construction

contract may be used.

5.6.9 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to excessive

S/CNN, impulse noise, and amplitude jitter.

5.7 Impulse Noise Measurement:

5.7.1 When specified by the borrower, impulse noise measurements

shall be made on trunk circuits and nonloaded subscriber loops.

For trunk circuits, the measurement shall be made between CO

locations. For nonloaded subscriber loops, the measurement shall

be made from the CO to the station protector of the NID at the

customer's access location.

5.7.2 Impulse noise is a measure of the presence of unusually

large noise excursions of short duration that are beyond the

normal background noise levels on a facility. Impulse noise is

typically measured by counting the number of occurrences beyond a

particular noise reference threshold in a given time interval.

The noise reference level is C-message weighted.

5.7.3 Method of Measurement: The impulse noise measurement

shall be performed using a 1,004 Hz tone at -13 dBm0 and in

accordance with ANSI T1.506-1990 and ANSI/IEEE 743-1984.

5.7.4 Test Equipment: The equipment for performing the

measurement shall be in accordance with ANSI/IEEE 743-1984.

5.7.5 Applicable Results: The impulse noise for both trunk and

nonloaded subscriber loop circuits shall not exceed 65 dBrnC0

(decibels relative to one picowatt reference noise level,

measured with C-message frequency weighting, referred to a zero

transmission level point). The impulse noise requirement shall

be based upon a maximum of 5 counts in a 5 minute period at equal

to or greater than the indicated noise thresholds.

5.7.6 Data Record: The measurement data shall be recorded.

Suggested formats similar to Format VI for nonloaded subscriber

loops and Format VII for trunk circuits in Paragraph 7 of this

bulletin or formats specified in the applicable construction

contract may be used.

5.7.7 Probable Causes for Nonconformance: Some of the causes

for failing to obtain the desired results may be due to excessive

transient signals originating from the various switching

operations.
Bulletin 1753F-201(PC-4)

Page 50

6. SHIELD OR ARMOR GROUND RESISTANCE MEASUREMENTS

6.1 Shield or armor ground resistance measurements shall be made

on completed lengths of copper cable and wire plant and fiber

optic cable plant.

6.2 Method of Measurement:

6.2.1 The shield or armor ground resistance measurement shall be

made between the copper cable and wire shield and ground and

between the fiber optic cable armor and ground, respectively.

The measurement shall be made either on cable and wire lengths

before splicing and before any ground connections are made to the

cable or wire shields or armors. Optionally, the measurement may

be made on cable and wire lengths after splicing, but all ground

connections must be removed from the section under test.

6.2.2 The method of measurement using either an insulation

resistance test set or a dc bridge type megohmmeter shall be as

shown in Figure 18.

6.3 Test Equipment:

6.3.1 The shield or armor ground resistance measurements may be

made using an insulation resistance test set, a dc bridge type

megohmmeter, or a commercially available fault locator.

6.3.2 The insulation resistance test set should have an output

voltage not to exceed 500 volts dc and may be hand cranked or

battery operated.

6.3.3 The dc bridge type megohmmeter, which may be ac powered,

should have scales and multipliers which make it possible to

accurately read resistance values of 50,000 ohms to 10 megohms.

The voltage that is applied to the shield or armor during the

test should not be less than "250 volts dc" nor greater than

"1,000 volts dc" when using an instrument having adjustable test

voltage levels.

6.3.4 Commercially available fault locators may be used in lieu

of the above equipment, if the devices are capable of detecting

faults having resistance values of 50,000 ohms to 10 megohms.

Operation of the devices and method of locating the faults should

be in accordance with manufacturer's instructions.

6.4 Applicable Results:

6.4.1 For all new copper cable and wire facilities and all new

fiber optic cable facilities, the shield or armor ground

resistance levels normally exceed 1 megohm-mile (1.6 megohm-km)

at 68°F (20°C). A value of 100,000 ohm-mile (161,000 ohm-km) at

68°F (20°C) shall be the minimum acceptable value of the shield

or armor ground resistance.
Bulletin 1753F-201(PC-4)

Page 51

6.4.2 Shield or armor ground resistance varies inversely with

length and temperature. In addition other factors which may

affect readings could be soil conditions, faulty test equipment

and incorrect test procedures.

6.4.3 For the resistance test method and dc bridge type

megohmmeter, the ohm-mile (ohm-km) value for the shield or armor

ground resistance shall be computed by multiplying the actual

scale reading in ohms on the test set by the length in miles (km)

of the cable or wire under test.

6.4.4 The objective shield or armor ground resistance may be

determined by dividing 100,000 by the length in miles (161,000 by

the length in km) of the cable or wire under test. The resulting

value is the minimum acceptable meter scale reading in ohms.

Examples for Paragraphs 6.4.3 and 6.4.4 of this bulletin are as

follows:

Equation 1. Test Set

 Scale Reading * Length = Resistance-Length

 75,000 ohms * 3 miles = 225,000 ohm-mile

 (75,000 ohms * 4.9 km = 367,000 ohm-km)

Equation 2. 100,000 ohm-mile ÷ Length = Minimum Acceptable

 Meter Scale Reading

 100,000 ohm-mile ÷ 3 miles = 33,333 ohms

 (161,000 ohm-km ÷ 4.9 km = 32,857 ohms)

6.4.5 Since the 33,333 ohms (32,857 ohms) is the minimum

acceptable meter scale reading and the meter scale reading was

75,000 ohms, the cable is considered to have met the 100,000

ohm-mile (161,000 ohm-km) requirement.

6.4.6 Due to the differences between various jacketing materials

used in manufacturing cable or wire and to varying soil

conditions, it is impractical to provide simple factors to

predict the magnitude of variation in shield or armor to ground

resistance due to temperature. The variations can, however, be

substantial for wide excursions in temperature from the ambient

temperature of 68°F (20°C).

6.5 Data Record: The data shall be corrected to the length

requirement of ohm-mile (ohm-km) and a temperature of 68°F (20°C)

and shall be recorded on a form specified in the applicable

construction contract.

6.6 Probable Causes for Nonconformance:

6.6.1 When results of resistance measurements are below the

100,000 ohm-mile (161,000 ohm-km) requirement at 68°F (20°C), the

jacket temperature, soil conditions, test equipment and method
Bulletin 1753F-201(PC-4)

Page 52

shall be reviewed before the cable or wire is considered a

failure. If the temperature is approximately 68°F (20°C) and

soil conditions are acceptable, and a reading of less than

100,000 ohm-mile (161,000 ohm-km) is indicated, check the

calibration of the equipment; as well as, the test method. If

the equipment was found to be out of calibration, recalibrate the

equipment and remeasure the cable or wire. If the temperature

was 86°F (30°C) or higher, the cable or wire shall be remeasured

at a time when the temperature is approximately 68°F (20°C). If

the test was performed in unusually wet soil, the cable or wire

shall be retested after the soil has reached normal conditions.

If after completion of the above steps, the resistance value of

100,000 ohm-mile (161,000 ohm-km) or greater is obtained, the

cable or wire shall be considered acceptable.

6.6.2 When the resistance value of the cable or wire is still

found to be below 100,000 ohm-mile (161,000 ohm-km) requirement

after completion of the steps listed in Paragraph 6.6.1 of this

bulletin, the fault shall be isolated by performing shield or

armor ground resistance measurements on individual cable or wire

sections.

6.6.3 Once the fault or faults have been isolated, the cable or

wire jacket shall be repaired in accordance with RUS Bulletin

1753F-401(PC-2), “RUS Standard for Splicing Copper and Fiber

Optic Cables,” or the entire cable or wire section may be

replaced at the request of the borrower.

7. DATA FORMATS

7.1 The following suggested formats listed in this section may

be used for recording the test data: