ASTM B786-00

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Designation: B 786 – 00
Standard Specification for
19 Wire Combination Unilay-Stranded Aluminum
Conductors for Subsequent Insulation
This standard is issued under the fixed designation B 786; 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
1.1 This specification covers bare combination unilay-
stranded conductors made from round wires of aluminum 1350
and 8000 series of aluminum alloys, for insulated conductors
for electrical purposes. Aluminum 1350 wires in tempers -H19
3 1
(extra hard), -H16 or -H26 ( ⁄4 hard), -H14 or -H24 ( ⁄2 hard),
and -H142 or -H242 ( ⁄2 hard) and 8000 series aluminum alloys
wires in tempers “0” and H1X or H2X are permitted. These
FIG. 1 Cross Section of Conductor
conductors shall be constructed with a central core wire
surrounded by two layers of helically laid wires, resulting in an
2. Referenced Documents
outer diameter equal to the compressed-stranded equivalent
2.1 The following documents of the issue in effect on date
conductors.
of material purchase form a part of this specification to the
NOTE 1—For the purpose of this specification, combination unilay
extent referenced herein.
conductor is defined as follows: a central core wire surrounded by a layer
2.2 ASTM Standards:
of six helically laid wires of the same diameter as the core wire with a
B 193 Test Method for Resistivity of Electrical Conductor
helically laid outer layer containing six smaller wires alternated between
Materials
six wires of the same diameter as the wires in the layer underneath. Both
layers have a common length and direction of lay (see Fig. 1).
B 230 Specification for Aluminum 1350-H19 Wire for Elec-
trical Purposes
1.1.1 For the purpose of this specification, normal conductor
B 263 Test Method for Determination of Cross-Sectional
classification (Class AA, A, B, C) is not applicable as these
Area of Stranded Conductors
conductors are intended for subsequent insulation. The descrip-
B 609 Specification for Aluminum 1350 Round Wire, An-
tive term combination unilay-stranded shall be used in place of
nealed and Intermediate Tempers, for Electrical Purposes
conductor classification (Note 2 and Note 3).
B 800 Specification for 8000 Series Aluminum Alloy Wire
NOTE 2—Prior to 1975, aluminum 1350 was designated as EC alumi-
for Electrical Purposes—Annealed and Intermediate Tem-
num.
pers
NOTE 3—The aluminum and temper designations conform to ANSI
B 801 Specification for Concentric-Lay-Stranded Conduc-
Standard H35.1. Aluminum 1350 corresponds to Unified Numbering
tors of 8000 Series Aluminum Alloy for Subsequent
System A91350 in accordance with Practice E 527. Unified Numbering
System alloy designations for 8000 Series aluminum alloys in accordance Covering or Insulation
with Practice E 527 are listed in Table 1 of Specification B 800.
E 29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
1.2 The values stated in inch-pound or SI units are to be
E 527 Practice for Numbering Metals and Alloys (UNS)
regarded separately as standard. The values in each system are
2.3 ANSI Standard:
not exact equivalents; therefore, each system shall be used
ANSI H35.1 Alloy and Temper Designation Systems for
independently of the other. Combining values from the two
Aluminum
systems may result in nonconformance with the specification.
2.4 NIST Standard:
1.2.1 For density, resistivity and temperature, the values
NBS Handbook 100
stated in SI units are to be regarded as standard.
Annual Book of ASTM Standards, Vol 02.03.
Annual Book of ASTM Standards, Vol 14.02.
This specification is under the jurisdiction of ASTM Committee B01 on
Annual Book of ASTM Standards, Vol 01.01.
Electrical Conductors and is the direct responsibility of Subcommittee B01.07 on
Available from American National Standards Institute, 11 West 42nd St., 13th
Conductors of Light Metals.
Floor, New York, NY 10036.
Current edition approved April 10, 2000. Published June 2000. Originally
Available from the National Institute of Standards and Technology, (NIST),
published as B 786 – 88. Last previous edition B 786 – 93.
Gaithersburg, MD 20899.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
B 786
3. Ordering Information 5.2 Other lays for special purposes shall be furnished by
special agreement between the manufacturer and the purchaser.
3.1 Orders for materials under this specification shall in-
clude the following information:
NOTE 4—Certain types of insulation conductors may require shorter lay
3.1.1 Conductor alloy, than other conductors. It is expected that special requirements regarding
length of lay will be specified by the purchaser in such instances.
3.1.2 Quantity of each size,
3.1.3 Conductor size: Circular-mil area or American Wire
5.3 The direction of lay shall be left-hand unless the
Gage, AWG (Section 6 and Table 1),
direction of lay is specified otherwise by the purchaser.
3.1.4 Stranding (see Explanatory Note 1),
6. Construction (Explanatory Note 1)
3.1.5 Temper (see Section 11),
6.1 The areas of cross section, numbers, and diameters of
3.1.6 Details of special-purpose lays, if required (see 5.2),
wires in the various conductors shall conform to the require-
3.1.7 When physical tests shall be made (see Sections 7 and
ments prescribed in Table 1 (Note 3) (see Fig. 1).
8),
6.2 The diameters of the wires listed in Table 2 are nominal.
3.1.8 Package size (see 16.1),
In order to produce an essentially round 19-wire construction,
3.1.9 Heavy wood lagging, if required (see 17.2),
the outer 12-wire layer in the combination unilay product is
3.1.10 Special package marking, if required (Section 17),
comprised of 6 wires of the same diameter as the wires in the
and
7-wire core, and 6 wires approximately 25 % smaller. The
3.1.11 Place of inspection (Section 15).
2-wire sizes are alternated around the 7-wire core.
4. Joints
7. Mechanical and Electrical Tests of Conductors not
4.1 Electric-butt welds, cold pressure welds, or electric-butt
Annealed after Stranding
cold-upset welds may be made in the finished individual wires
7.1 Wires composing the conductors shall be tested prior to
composing the conductor, but shall not be closer together than
stranding in accordance with the applicable specification (see
1 ft (Explanatory Note 2).
11.1.2), and tests on the completed conductor are not required.
However, when requested by the purchaser and agreed to by
5. Lay
the manufacturer at time of ordering, the tension tests of wires
5.1 For combination unilay conductors the lay of a layer of
before stranding may be waived and the completed conductor
wires shall be not less than 8 nor more than 16 times the
tested in accordance with 7.2, or wires removed from the
outside diameter of the outer layer.
completed conductor tested in accordance with 7.5.
7.2 When the completed conductor is tested as a unit, the
breaking strength shall be not less than the rated strength of
TABLE 1 Construction Requirements for 19-Wire Combination
Unilay Stranded Aluminum Conductors 1350-H19 conductors or the minimum rated strength of 1350-
A B
H16, -H26, -H14, -H24, -H142, and -H242 conductors if
Wire D Wire D
1 2
Area of Size, American (or
Diameter Diameter
failure occurs in the free length at least 1 in. (25 mm) beyond
Cross-Section, Brown and Sharpe)
cmil Wire Gage
mils mm mils mm the end of either gripping device. The strength shall be not less
than 95 % of the rated or minimum rated strength if failure
556 500 185.3 4.71 135.6 3.50
500 000 175.6 4.46 128.5 3.31
occurs inside, or within 1 in. of the end of either gripping
477 000 171.5 4.36 125.5 3.24
device. The breaking strength of 1350-H16, -H26, -H14, -H24,
450 000 166.6 4.23 121.9 3.14
-H142, and -H242 conductors shall be not greater than their
397 500 156.6 3.99 114.6 2.96
350 000 146.9 3.98 107.5 2.95
maximum rated strengths. The free length between grips of the
336 400 144.0 3.73 105.4 2.77
test specimen shall be not less than 24 in. (600 mm) and care
300 000 136.0 3.66 99.6 2.72
shall be taken to ensure that the wires in the conductor are
266 800 128.3 3.45 93.9 2.57
250 000 124.2 3.26 90.9 2.42
evenly gripped during the test (Explanatory Note 3).
211 600 0000 114.2 3.15 83.6 2.34
7.3 The rated strength of 1350-H19 conductors and the
167 800 000 101.7 2.90 74.5 2.16
minimum rated strength of 1350-H16, -H26, -H14, -H24,
133 100 00 90.6 2.58 66.3 1.92
105 600 0 80.7 2.30 59.1 1.71
-H142, and -H242 conductors shall be taken as 93 % of the
83 690 1 71.8 2.05 52.6 1.52
sum of the specified minimum average tensile strengths of the
66 360 2 64.0 1.82 46.8 1.36
component wires for 1350-H19 conductors, as prescribed in
52 620 3 57.0 1.62 41.7 1.21
41 740 4 50.7 1.45 37.1 1.08
Table 1, Tensile Requirements, of Specification B 230, and of
33 090 5 45.2 1.29 33.1 0.96
the sum of the specified minimum tensile strengths of the
26 240 6 40.2 1.15 29.4 0.85
20 820 7 35.8 1.02 26.2 0.76 component wires for 1350-H16, -H26, -H14, -H24, -H142, and
16 510 8 31.9 0.81 23.4 0.60
-H242 conductors, as prescribed in Specification B 609, as
13 090 9 28.4 0.72 20.8 0.54
applicable. The maximum rated strength of the 1350-H16,
10 380 10 25.3 0.64 18.5 0.48
-H26, -H14, -H24, -H142 and -H242 conductors shall be taken
6 530 12 20.1 0.51 14.7 0.38
A as the sum of the specified maximum strengths of the compo-
Equation to calculate D :
area of cross section ~cmil! nent wires, as prescribed in Specification B 609, as applicable.
˛
16.2149
The rated strengths shall be calculated using specified nominal
B
Equation to calculate
wire diameters.
D : 5 D 3 0.743.
2 1
7.4 Rated strength and breaking strength values shall be
B 786
A
TABLE 2 Diameters, Areas and Mass of 19-Wire Combination Unilay Stranded Aluminum Conductor
Nominal Conductor Direct Current Resistance
Size of
Nominal Area Mass
B
Diameter at 20°C
Conductor,
cmil or
lb/1000 V/1000
2 2
in. mm in. mm kg/km V/km
AWG
ft ft
556 500 0.827 21.0 0.4371 282 521 775 0.0312 0.1024
500 000 0.784 19.9 0.3927 253 468 697 0.0347 0.1139
477 000 0.766 19.5 0.3746 242 447 665 0.0364 0.1194
450 000 0.744 18.9 0.3534 228 421 627 0.0385 0.1263
397 500 0.699 17.8 0.3122 201 372 554 0.0436 0.1431
350 000 0.656 16.7 0.2749 177 328 488 0.0495 0.1624
336 400 0.643 16.3 0.2642 170 315 469 0.0516 0.1693
300 000 0.607 15.4 0.2356 152 281 418 0.0578 0.1896
266 800 0.573 14.6 0.2095 135 250 372 0.0650 0.2133
250 000 0.554 14.1 0.1963 127 234 348 0.0694 0.2277
0000 0.510 13.0 0.1662 107 198 295 0.0820 0.2690
000 0.454 11.5 0.1318 85.0 157 234 0.103 0.3389
00 0.404 10.3 0.1045 67.4 125 185 0.130 0.4275
0 0.360 9.14 0.08291 53.5 98.9 147 0.164 0.5387
1 0.321 8.15 0.06573 42.4 78.4 117 0.207 0.6798
2 0.286 7.26 0.05212 33.6 62.1 92.4 0.261 0.8573
3 0.254 6.45 0.04133 26.7 49.3 73.4 0.330 1.0814
4 0.226 5.74 0.03278 21.1 39.1 58.2 0.416 1.3633
5 0.202 5.13 0.02599 16.8 31.0 46.1 0.523 1.72
6 0.179 4.55 0.02061 13.3 24.6 36.6 0.661 2.1684
7 0.160 4.06 0.01635 10.5 19.5 29.0 0.834 2.7362
8 0.143 3.63 0.01297 8.37 15.5 23.1 1.05 3.4464
9 0.127 3.23 0.01028 6.63 12.3 18.3 1.32 4.3307
10 0.113 2.87 0.00816 5.26 9.73 14.5 1.67 5.4790
12 0.090 2.29 0.00513 3.31 6.12 9.11 2.67 8.7598
A
Mass and electrical resistance are based on aluminum 1350.
B
To calculate the diameter, multiply the large wire diameter in Table 1 times 3 and add two times the small wire diameter.
Example: AWG 4/0 diameter 5 [3(114.2) + 2(83.6)] 5 509.8
rounded to three significant figures, in the final value only, in layer of each conductor sample to determine conformance with
accordance with the rounding method in Practice E 29. 8.2 or on the conductor as a unit to determine conformation
7.5 When wires are removed from the completed conductor with 8.3.
and tested, 1350-H19 wires shall have minimum tensile 8.2 When wires removed from the completed conductor are
strengths not less than 95 % of the tensile strengths prescribed tested, 1350-H26, -H24, and -H242 wires shall have tensile
for individual tests in Table 1, Tensile Requirements, of strengths not less than 95 % of the minimum tensile strength
Specification B 230. 1350-H16, -H26, -H14, -H24, -H142, and nor more than 105 % of the maximum tensile strength pre-
-H242 wires shall have tensile strengths not less than 95 % of scribed in Specification B 609, as applicable (Explanatory Note
the minimum tensile strength nor more than 105 % of the 4).
maximum tensile strength prescribed in Specification B 609, as 8.3 When the completed conductor is tested as a unit, the
applicable (Explanatory Note 4). breaking strengths of 1350-H26, -H24, and -H242 conductors
7.6 All wires composing the conductors shall be capable of shall conform with 7.2, 7.3, and 7.4.
meeting the bending properties stated in Specification B 230 8.4 All wires composing the conductors shall be capable of
after stranding. Routine production testing after stranding is meeting the bending properties stated in Specification B 230
not required. after stranding. Routine production testing after stranding is
7.7 Mechanical and electrical tests of conductors in 8000 not required.
series aluminum alloys in “0” temper, H1X or H2X wire and 8.5 Mechanical and electrical tests of conductors of 8000
not annealed after stranding shall be in accordance with series aluminum alloys fabricated from wires other than H2X
Section 9 of Specification B 801. and annealed after stranding to meet “0” temper or H2X
requirements shall be in accordance with Section 10 of
8. Mechanical and Electrical Tests of Conductors
Specification B 801.
Annealed after Stranding
9. Mass and Resistance
8.1 Tensile properties and electrical resistivity shall be
determined on Samples taken from 10 % of the reels or coils of 9.1 The mass and electrical resistance of a unit length of
conductor, but from not less than five (or all if the lot is less stranded conductor are a function of the length of lay. The
than five) reels or coils. Resistivity shall be determined as approximate mass and electrical resistance may be determined
prescribed in the Resistivity section of Specification B 230 on using the standard increment of 2 %. When greater accuracy is
one wire from each conductor sample except this test is not desired, the increment based on the specific lay of the conduc-
required if performed previously on the 1350-H19 wire. At the tor may be calculated (Explanatory Note 1).
manufacturer’s option, tension tests shall be made either on 9.2 The maximum electrical resistance of a unit length of
one of the inner s
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