ASTM B784-00

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Designation: B 784 – 00
Standard Specification for
Modified Concentric-Lay-Stranded Copper Conductors for
Use in Insulated Electrical Cables
This standard is issued under the fixed designation B 784; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Area of Stranded Conductors
B 354 Terminology Relating to Uninsulated Metallic Elec-
1.1 This specification covers bare modified concentric-lay-
trical Conductors
stranded conductors made from round copper wires, either
2.3 Other Standard:
uncoated or coated with tin, lead, or lead alloy for general use
NBS Handbook 100
in insulated electrical cables. These conductors shall be con-
structed with a central core consisting of not more than seven
3. Ordering Information
wires, surrounded by one or more layers of helically laid wires.
3.1 Orders for material under this specification shall include
1.2 For the purposes of this specification, conductors are
the following information:
classified as follows (Explanatory Note 1 and Note 2):
3.1.1 Quantity of each size and class,
1.2.1 Class B Modified—Conductors to be insulated with
3.1.2 Conductor size: circular-mil area or American Wire
various materials such as rubber, paper, and crosslink polyeth-
Gage (AWG) (Section 6),
ylene.
3.1.3 Class (see 1.2 and Table 1),
1.2.2 Class C Modified and Class D Modified—Conductors
3.1.4 Temper (see 10.2),
where greater flexibility is required than is provided by Class
3.1.5 Whether coated or uncoated; if coated, designate type
B Modified conductors.
of coating (see 10.1 and 10.2),
1.3 The SI values of density and resistivity are to be
3.1.6 Details of special-purpose lays, if required (see 5.2),
regarded as standard. For all other properties the inch-pound
3.1.7 Lagging, if required (see 14.2),
values are to be regarded as standard and the SI units may be
3.1.8 Special package marking, if required (Section 13),
approximate.
3.1.9 Place of inspection (Section 12), and
NOTE 1—The significant differences in this specification from Specifi-
cation B 8 are as follows: (1) The central core is permitted to contain up
4. Joints
to seven wires drawn into the assembly with an infinite length of lay while
4.1 Welds and brazes may be made in rods or in wires prior
Specification B 8 permits only one, and (2) The construction is applicable
to final drawing. Welds and brazes may be made in the finished
only to stranded assemblies of 19 or more wires.
individual wires composing the conductor, but shall not be
2. Referenced Documents
closer together than prescribed in Table 2.
2.1 The following documents of the issue in effect at the
5. Lay
date of material purchase form a part of this specification to the
5.1 The lay of a layer of wires shall be not less than eight
extent referenced herein.
nor more than sixteen times the outside diameter of that layer,
2.2 ASTM Standards:
except that for conductors composed of 37 wires or more, this
B 3 Specification for Soft or Annealed Copper Wire
requirement shall apply only to the two outer layers. The lay of
B 8 Specification for Concentric-Lay-Stranded Copper
the layers other than the two outer layers shall be at the option
Conductors, Hard, Medium-Hard, or Soft
of the manufacturer, unless otherwise agreed upon.
B 33 Specification for Tinned Soft or Annealed Copper
5.2 Other lays for special purposes shall be furnished by
Wire for Electrical Purposes
special agreement between the manufacturer and the purchaser
B 189 Specification for Lead-Coated and Lead-Alloy
(Explanatory Note 3).
Coated Soft Copper Wire for Electrical Purposes
5.3 The direction of lay of the outer layer shall be left-hand
B 263 Test Method for Determination of Cross-Sectional
unless the direction of lay is specified otherwise by the
purchaser.
This specification is under the jurisdiction of ASTM Committee B01 on
5.4 The direction of lay shall be reversed in successive
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
Conductors of Copper and Copper Alloys.
Current edition approved May 10, 2000. Published July 2000. Originally
published as B 784 – 88. Last previous edition B 784 – 94. Available from the National Technical Information Service, 5285 Port Royal
Annual Book of ASTM Standards, Vol 02.03. Rd., Springfield, VA 22161.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
B 784
TABLE 1 Construction Requirements of Modified Concentric-Lay-Stranded Copper Conductors
NOTE 1—See Explanatory Note 5.
Class B Modified Class C Modified Class D Modified
Size
Circular Mils American Diameter Diameter Diameter
Number of Number of Number of
Wire Gage
Wires Wires Wires
(mils) (mm) (mils) (mm) (mils) (mm)
A
5 000 000 217 151.8 3.86 271 135.8 3.45 271 135.8 3.45
4 000 000 217 144.0 3.66 271 128.9 3.27 271 128.9 3.27
4 000 000 217 135.8 3.45 271 121.5 3.09 271 121.5 3.09
3 500 000 169 143.9 3.66 217 127.0 3.23 271 113.6 2.89
A
3 000 000 169 133.2 3.38 217 117.6 2.99 271 105.2 2.67
A
2 500 000 127 140.3 3.56 169 121.6 3.09 217 107.3 2.73
A
2 000 000 127 125.5 3.19 169 108.8 2.76 217 96.0 2.44
1 900 000 127 122.3 3.11 169 106.0 2.69 217 93.6 2.38
1 800 000 127 119.1 3.03 169 103.2 2.62 217 91.1 2.31
A
1 750 000 127 117.4 2.98 169 101.8 2.59 217 89.8 2.28
1 700 000 127 115.7 2.94 169 100.3 2.55 217 88.5 2.25
1 600 000 127 112.2 2.85 169 97.3 2.47 217 85.9 2.18
A
1 500 000 91 128.4 3.26 127 108.7 2.76 169 94.2 2.39
1 400 000 91 124.0 3.15 127 105.0 2.67 169 91.0 2.31
1 300 000 91 119.5 3.04 127 101.2 2.57 169 87.7 2.23
1 250 000 91 117.2 2.98 127 99.2 2.52 169 86.0 2.18
1 200 000 91 114.8 2.92 127 97.2 2.47 169 84.3 2.14
1 100 000 91 109.9 2.79 127 93.1 2.36 169 80.7 2.05
A
1 000 000 61 128.0 3.25 91 104.8 2.66 127 88.7 2.25
900 000 61 121.5 3.09 91 99.4 2.52 127 84.2 2.14
A
800 000 61 114.5 2.91 91 93.8 2.38 127 79.4 2.02
A
750 000 61 110.9 2.82 91 90.8 2.31 127 76.8 1.95
A
700 000 61 107.1 2.72 91 87.7 2.23 127 74.2 1.88
650 000 61 103.2 2.62 91 84.5 2.15 127 71.5 1.82
A
600 000 61 99.2 2.52 91 81.2 2.06 127 66.7 1.69
550 000 61 95.0 2.41 91 77.7 1.97 127 65.8 1.67
A
500 000 37 116.2 2.95 61 90.5 2.30 91 74.1 1.88
450 000 37 110.3 2.80 61 85.9 2.18 91 70.3 1.79
A
400 000 37 104.0 2.64 61 81.0 2.06 91 66.3 1.68
A
350 000 37 97.3 2.47 61 75.7 1.92 91 62.0 1.57
A
300 000 37 90.0 2.29 61 70.1 1.78 91 57.4 1.46
A
250 000 37 82.2 2.09 61 64.0 1.63 91 52.4 1.33
A
211 000 0000 19 105.5 2.68 37 75.6 1.92 61 58.9 1.50
A
167 000 000 19 94.0 2.39 37 67.3 1.71 61 52.4 1.33
A
133 000 00 19 83.7 2.13 37 60.0 1.52 61 46.7 1.19
A
105 000 0 19 74.5 1.89 37 53.4 1.36 61 41.6 1.06
A
83 000 1 19 66.4 1.69 37 47.6 1.21 61 37.0 0.94
A
These sizes of conductors provide for one or more schedules of preferred series and commonly are used in the industry. The sizes not marked are given simply as
a matter of reference and it is suggested that their use be discouraged.
TABLE 2 Minimum Distance Between Joints in the Completed
slightly compressed, thereby reducing the outside diameter of
Conductor
the conductor by not more than 3 %, provided that the area of
Number of Wires in Conductor Soft All Classes
cross section after stranding is in accordance with Section 11.
19 1 ft
A
20 and over 1 ft in a layer
7. Physical and Electrical Tests of Stranded Conductors
A
Except as indicated, the limitations apply to closeness of joints throughout the
of Soft Wires
completed conductor.
7.1 Tests for the electrical properties of wires composing
layers, unless otherwise specified by the purchaser. conductors made from soft or annealed copper wire, bare or
coated, shall be made before stranding.
6. Construction
7.2 Tests for the physical properties of soft or annealed
6.1 The areas of cross section, numbers, and diameters of copper wire, bare or coated, may be made upon the wires
before stranding or upon wires removed from the complete
wires in the various classes of concentric-lay-stranded conduc-
tors shall conform to the requirements prescribed in Table 1. stranded conductor, but need not be made upon both. Care shall
6.2 The diameters of the wires listed in Table 1 are nominal. be taken to avoid mechanical injury to wire removed from the
Where “combination strand’’ is required in order to insulate the conductor for the purpose of testing.
conductor properly (strands in the outer layer having a larger 7.3 The physical properties of wires when tested before
diameter than those in the inner layers) the diameters shall be stranding shall conform to the applicable requirements of 10.2.
subject to a tolerance of 6 5 %, provided that the area of cross 7.4 The physical properties of wires removed from the
section after stranding is in accordance with Section 11. completed stranded conductor shall be permitted to vary from
6.3 Where compressed stranding is required in order to the applicable requirements of 10.2 by the following amounts
insulate the conductor properly, one or more layers of any (Explanatory Note 4):
stranded conductor consisting of 19 wires or more may be 7.4.1 Average of Results Obtained on All Wires Tested—The
B 784
minimum elongation required shall be reduced in numerical shall be not less than 98 % of the area indicated in Column 1
value 5 (for example, from 30 to 25 %) from the numerical of Table 1. Unless otherwise specified by the purchaser, the
requirements for the wire before stranding. manufacturer may have the option of determining the cross-
7.4.2 Results Obtained on Individual Wires—The elonga- sectional area by either of the following methods; except that
tion of individual wires shall be reduced in numerical value 15 in case of a question regarding area compliance, the method of
from the minimum requirements before stranding (that is, 10 in 11.1.2 shall be used.
addition to the 5 allowed in 7.4.1), but in no case shall the 11.1.1 The area of cross section of a conductor may be
elongation of any individual wire be less than 5 %. determined by calculations from diameter measurements, ex-
7.5 In the event that the requirements prescribed in 7.4.2 are pressed to four decimal places, of its component wires at any
met but those prescribed in 7.4.1 are not met, a retest shall be point when measured perpendicularly to their axes.
permitted wherein all wires of the conductor shall be tested for 11.1.2 The area of cross section of a conductor may be
the purpose of final determination of conformance to 7.4. determined by Test Method B 263. In applying that method, the
7.6 Elongation tests to determine compliance shall not be increment in mass resulting from stranding may be the appli-
made on the conductor as a unit (Explanatory Note 6). cable value specified in 9.1 or may be calculated from the
7.7 If a tinning, lead-coating, or lead-alloy-coating test is measured component dimensions of the sample under test. In
required, it shall be made on the wires prior to stranding. case of a question regarding area compliance, the actual mass
increment due to stranding shall be calculated.
8. Density
8.1 For the purpose of calculating mass per unit length, 12. Inspection
cross sections, etc., the density of the copper shall be taken as
12.1 Unless otherwise specified in the contract or purchase
3 3
0.32117 lb/in. or 8.89 g/cm at 20°C (Note 2 and Explanatory
order, the manufacturer shall be responsible for the perfor-
Note 7).
mance of all inspection and test requirements specified.
12.2 All inspections and tests shall be made at the place of
NOTE 2—The term “mass” is being used in this specification as being
manufacture unless otherwise agreed upon by the manufacturer
more technically correct. It replaces the term “weight.”
and the purchaser at the time of purchase.
9. Mass and Resistance
12.3 The manufacturer shall afford the inspector represent-
9.1 The mass and electrical resistance of a unit length of ing the purchaser all reasonable manufacturer’s facilities to
stranded conductor are a function of the length of lay. The satisfy that the material is being furnished in accordance with
approximate mass and electrical resistance may be determined this specification.
using the standard increments shown in Table 3. When greater
13. Product Marking
accuracy is desired, the increment based on the specific lay of
the conductor may be calculated (Explanatory Note 8).
13.1 The net mass, length (or lengths and number of
lengths, if more than one length is included in the package),
10. Requirements for Wires
size, kind of conductor, purchase order number, and any other
10.1 The purchaser shall designate the type of wire and the
marks required by the purchase order shall be marked on a tag
kind of coating, if any, to be used in the conductor.
attached to the end of the conductor inside of the package. The
10.2 Before stranding, the copper wire used shall meet all of
same information, together with the manufacturer’s serial
the requirements of ASTM Specifications B 3, B 33, and B 189
number (if any) and all shipping marks required by the
that are applicable to its type.
purchaser, shall appear on the outside of each package.
10.3 The central core shall be made of wire of the same type
and temper as the concentric layers, unless otherwise specified. 14. Packaging and Package Marking
14.1 Package sizes for conductors shall be agreed upon by
11. Variation in Area
the manufacturer and the purchaser in the placing of individual
11.1 The area of cross section of the completed conductor
orders (Explanatory Note 9).
14.2 The conductors shall be protected against damage in
TABLE 3 Standard Increments Due to Stranding
ordinary handling and shipping. If heavy wood lagging is
Increment of Resistance
Type of Conductor
required, it shall be specified by the purchaser at the time of
and Mass, %
purchase.
Classes B Modified, C Modified, and D 2
Modified, 2 000 000 cmil and under
Over 2 000 000 to 3 000 000 cmil 3 15. Keywords
Over 3 000 000 to 4 000 000 cmil 4
15.1 copper conductors for insulated wires; copper modified
Over 4 000 000 to 5 000 000 cmil 5
concentric-lay-stranded; electrical copper conductors
B 784
TABLE 4 Diameter, Area, and Mass of Modified Concentric-Lay-Stranded Copper Conductors
Size of
Nominal Conductor Diameter
Conductor A
Class B Modified Area Mass, lb
cmil or AWG
2 2
(in.) (mm) (in.) (mm) per 1000 ft per Mile (kg/m)
Number
B
5 000 000 cmil 2.581 65.56 3.927 2533.54 15890 83899 23.68
4 000 000 cmil 2.448 62.18 3.534 2280.00 14300 75504 21.31
4 000 000 cmil 2.309 58.65 3.142 2027.09 12590 66475 18.76
3 500 000 cm
...