ASTM B778-97
(Specification)Standard Specification for Shaped Wire Compact Concentric-Lay-Stranded Aluminum Conductors (AAC/TW)
Standard Specification for Shaped Wire Compact Concentric-Lay-Stranded Aluminum Conductors (AAC/TW)
SCOPE
1.1 This specification covers shaped wire compact concentric-lay-stranded aluminum conductor (AAC/TW) and its component wires for use as overhead electrical conductors (Explanatory Notes 1 and 2).
1.2 The values stated in inch-pound units are to be regarded as the standard with the exception of temperature and resistivity. The SI equivalents of inch-pound units may be approximate. Note 1-AAC/TW is designed to increase the aluminum area for a given diameter of conductor by the use of trapezoidally shaped wires (TW). The conductors consist of a central core of one round aluminum wire or a seven-strand compact round core surrounded by two or more layers of trapezoidal aluminum 1350-H19 wires. For the purposes of this specification, the sizes listed are tabulated on the basis of the finished conductor having an area equal to that of specific sizes of standard AAC (Table 1) or in fixed diameter increments (Table 2) so as to facilitate conductor selection. Note 2-The aluminum and temper designations conform to ANSI Standard H35.1. Aluminum 1350 corresponds to Unified Numbering System (UNS) A91350 in accordance with Practice E527.
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: B 778 – 97
Standard Specification for
Shaped Wire Compact Concentric-Lay-Stranded Aluminum
Conductors (AAC/TW)
This standard is issued under the fixed designation B 778; 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.
TABLE 1 Construction Requirements for Shaped Wire Compact
1. Scope
Concentric-Lay-Stranded Aluminum Conductors Sized to Have
1.1 This specification covers shaped wire compact
Areas Equal to AAC Size
concentric-lay-stranded aluminum conductor (AAC/TW) and
Nominal
AAC/TW Number of Nominal Rated
its component wires for use as overhead electrical conductors
Outside Number of
Conductor Aluminum Mass, Strength,
Diameter, Layers
(Explanatory Note 1 and Note 2).
Size, kcmil Wires lb/1000 ft 1000 lbf
A
in.
1.2 The values stated in inch-pound units are to be regarded
336.4 0.612 17 2 315.3 6.02
as the standard with the exception of temperature and resistiv-
397.5 0.661 17 2 372.6 6.96
ity. The SI equivalents of inch-pound units may be approxi-
477.0 0.720 17 2 447.1 8.36
mate. 500.0 0.736 17 2 468.7 8.76
556.5 0.775 17 2 521.6 9.75
NOTE 1—AAC/TW is designed to increase the aluminum area for a
600.0 0.803 17 2 562.4 10.52
636.0 0.825 17 2 596.1 11.1
given diameter of conductor by the use of trapezoidally shaped wires
700.0 0.864 17 2 656.1 12.3
(TW). The conductors consist of a central core of one round aluminum
750.0 0.893 17 2 702.1 13.1
wire or a seven-strand compact round core surrounded by two or more
795.0 0.919 17 2 745.1 13.6
layers of trapezoidal aluminum 1350-H19 wires. For the purposes of this
900.0 0.990 31 3 843.6 15.4
specification, the sizes listed are tabulated on the basis of the finished
954.0 1.018 31 3 894.2 16.4
conductor having an area equal to that of specific sizes of standard AAC
1000.0 1.041 31 3 937.3 17.1
1033.5 1.057 31 3 968.7 17.7
(Table 1) or in fixed diameter increments (Table 2) so as to facilitate
1113.0 1.095 31 3 1043.2 19.1
conductor selection.
1192.5 1.132 31 3 1117.7 20.4
NOTE 2—The aluminum and temper designations conform to ANSI
1272.0 1.168 31 3 1192.2 21.8
Standard H 35.1. Aluminum 1350 corresponds to Unified Numbering
1351.5 1.202 31 3 1266.3 23.2
System (UNS) A91350 in accordance with Practice E 527.
1431.0 1.236 31 3 1341.3 24.0
1590.0 1.315 49 4 1490.3 27.0
2. Referenced Documents 1750.0 1.377 49 4 1640.3 29.7
2000.0 1.468 49 4 1893.0 33.9
2.1 The following documents of the issue in effect on date
2500.0 1.648 71 5 2366.2 41.9
of material purchase form a part of this specification to the 3000.0 1.799 71 5 2839.5 50.3
A
extent referenced herein.
1 in. 5 25.4 mm.
2.2 ASTM Standards:
B 230 Specification for Aluminum 1350-H19 Wire for Elec-
ANSI H35.1 American National Standard Alloy and Tem-
trical Purposes 5
per Designation Systems for Aluminum
B 263 Test Method for Determination of Cross-Sectional
NBS Handbook 100—Copper Wire Tables
Area of Stranded Conductors
B 354 Terminology Relating to Uninsulated Metallic Elec-
3. Ordering Information
trical Conductors
3.1 Orders for material under this specification shall include
E 29 Practice for Using Significant Digits in Test Data to
the following information:
Determine Conformance with Specifications
3.1.1 Quantity of each size,
E 527 Practice for Numbering Metals and Alloys (UNS)
3.1.2 Conductor size: kcmil area and diameter (Table 1 and
2.3 Other Documents:
Table 2),
3.1.3 Special tension test, if required (see 8.2),
3.1.4 Place of inspection (Section 15),
This specification is under the jurisdiction of ASTM Committee B-1 on
3.1.5 Package size and type (see 15.1),
Electrical Conductors and is the direct responsibility of Subcommittee B 01.07on
Conductors of Light Metals.
Current edition approved Oct. 10, 1997. Published December 1997. Originally
published as B 778 – 87. Last previous edition B 778 – 92. Available from American National Standards Institute, 11 West 42nd Street,
Annual Book of ASTM Standards, Vol 02.03. 13th Floor, New York, NY 10036.
3 6
Annual Book of ASTM Standards, Vol 14.02. Available from National Institute of Standards and Technology (NIST),
Annual Book of ASTM Standards, Vol 01.01. Gaithersburg, MD 20899.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 778
TABLE 2 Construction Requirements for Shaped Wire Compact
6.4 The direction of lay of the outside layer of aluminum
Concentric-Lay-Stranded Aluminum Conductors, in
wires shall be right-hand.
Fixed-Diameter Increments
6.5 The direction of lay of the aluminum wires shall be
Nominal
AAC/TW Number of Nominal Rated reversed in successive layers.
Outside Number of
Conductor Aluminum Mass, Strength,
6.6 For the purpose of this specification the lay factor is the
Diameter, Layers
Size, kcmil Wires lb/1000 ft 1000 lbf
in.
length of lay of a given layer divided by its outside diameter.
322.5 0.60 17 2 302.3 5.88
7. Construction
384.5 0.65 17 2 360.4 6.74
449.4 0.70 17 2 421.2 7.88
7.1 The nominal aluminum cross-sectional area, the outside
521.7 0.75 17 2 489.0 9.14
diameter, the nominal number of aluminum wires, the number
595.8 0.80 17 2 558.4 10.44
678.2 0.85 17 2 635.7 11.88
of layers, the linear density, and the rated strength, of the
761.5 0.90 17 2 713.7 13.07
shaped wire compact concentric-lay-stranded aluminum con-
854.2 0.95 17 2 800.6 14.86
918.8 1.00 31 3 861.2 15.76 ductors, shall be as shown in Table 1 and Table 2.
1020.0 1.05 31 3 956.0 17.50
NOTE 3—Exception to 7.1. Because the final design of a shaped wire
1123.1 1.10 31 3 1052.7 19.26
1234.2 1.15 31 3 1156.8 21.17 compact conductor is contingent on several factors such as layer diameter,
1346.8 1.20 31 3 1262.3 23.10
wire width and thickness, and the like, the actual configuration of a given
1467.9 1.25 31 3 1375.9 24.65
size may vary between manufacturers. This might result in a slight
1583.2 1.30 34 3 1483.9 26.59
variation in the number of wires and number of layers, from that shown in
1682.7 1.35 49 4 1577.5 28.55
Table 1 and Table 2, and also in the dimensions of the individual wires.
1812.7 1.40 49 4 1699.0 30.74
1954.3 1.45 49 4 1832.1 33.16
8. Rated Strength of Conductor
2093.6 1.50 49 4 1981.6 35.51
2245.4 1.55 49 4 2125.7 37.30
8.1 The rated strength of a conductor, as shown in Table 1
2388.1 1.60 52 4 2260.3 39.67
2514.8 1.65 71 5 2379.5 42.17 and Table 2, shall be taken as the percentage, indicated in Table
2667.2 1.70 71 5 2524.5 44.74
3, in accordance with the number of aluminum layers, of the
2844.5 1.75 71 5 2692.2 47.70
sum of the wire strengths calculated from the specified
3006.2 1.80 71 5 2873.0 50.43
diameter of the round wires having the same area as the
trapezoidal wires used in the manufacture of the conductor, and
the appropriate minimum average tensile strength given in
3.1.6 Special package markings, if required (Section 15),
Specification B 230.
and
8.1.1 The rated strengths of conductors calculated in accor-
3.1.7 Heavy wood lagging, if required (see 15.3).
dance with 8.1 and 8.3 are listed in Table 1 and Table 2.
4. Requirement for Wires 8.2 Tests to confirm that the rated strength of the conductor
is met are not required by this specification, but shall be made
4.1 Before stranding, the trapezoidal aluminum wires shall
if agreed upon between the manufacturer and the purchaser at
conform to the requirements of Specification B 230 except for
the time of placing an order. When tested, the breaking strength
shape and diameter tolerance. The tensile strength and elonga-
of the conductor shall be not less than the rated strength if
tion requirements of trapezoidal wires shall be the same as for
failure occurs in the free length at least 1 in. (25 mm) beyond
round wires of equal area. The area tolerances shall be such
the end of either gripping device, or shall be not less than 95 %
that the finished conductor conforms to Section 11.
of the rated strength if failure occurs inside or within 1 in. of
5. Joints
the end of either gripping device (Explanatory Note 2).
8.3 Rated strength and breaking strength values shall be
5.1 Electric-butt welds, electric-butt cold-upset welds, or
rounded to three significant figures in the final value only, in
cold-pressure welds may be made in the individual aluminum
accordance with Practice E 29.
wires during the stranding process. No weld shall occur within
50 ft (15 m) of any other weld in the completed conductor
9. Density
(Explanatory Note 3).
9.1 For the purpose of calculating mass per unit length,
6. Lay cross-sections, and the like, the density of aluminum 1350 shall
3 3
be taken as 0.0975 lb/in. (2705 kg/m ) at 20°C.
6.1 The preferred lay of the outside layer of aluminum wires
of shaped wire aluminum conductors, having multiple layers of
10. Mass and Electrical Resistance
aluminum wires is 11 times the outside diameter of the
10.1 The mass per unit length and electrical resistance of a
conductor but the lay shall not be less than 10 nor more tha
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