BARE CONDUCTOR

AAC Conductor IEC 61089

AAC Conductor is a bare overhead line conductor made entirely of hard-drawn aluminium wires, stranded in concentric layers in accordance with IEC 61089. The standard designates this homogeneous construction A1, and the code number of each size equals its aluminium area in mm², so a conductor is identified by code, material and wire count, for example 250-A1-19. Without a steel core, AAC combines low weight with good conductivity for lines built on short spans.

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All wires in an AAC Conductor are round, of equal diameter and of the same hard-drawn aluminium grade. A single centre wire is surrounded by one or more helical layers, each laid in the opposite direction to the one below. Because there is no steel or alloy component, the whole cross-section conducts current, and both the linear mass and the d.c. resistance follow directly from the aluminium area and the stranding increments set by the standard.

Conductor Construction

Wire material: Round hard-drawn aluminium wires, designation A1, having before stranding the properties specified in IEC 889 (IEC 61089 Clauses 1.1 and 5.1).
Stranding: Concentric lay, with successive layers laid in reverse directions and the wires of each layer placed evenly and closely on the layer beneath (IEC 61089 Clauses 5.4.1 to 5.4.3).
Outer layer direction: Right-hand, unless a different direction is stated in the purchase order (IEC 61089 Clause 5.4.2).
Lay ratio: Between 10 and 14 for the outer layer and between 10 and 16 for inner layers, with no layer exceeding the lay ratio of the layer directly beneath it (IEC 61089 Clauses 5.4.5 and 5.4.6).
Outer wires: When the conductor is cut, the outer wires stay in position or can be returned to position by hand (IEC 61089 Clause 5.4.7).
Wire joints: Allowed only in wires that break unavoidably during stranding, never to make up length, and kept at least 15 m apart; Table 1 of the standard sets the permitted number per conductor length for conductors with one to four aluminium layers (IEC 61089 Clauses 5.5.3 and 5.5.4).
Joint strength: At least 75 MPa for annealed electric butt-welded joints and at least 130 MPa for cold pressure or electric butt cold upset welded joints (IEC 61089 Clause 5.5.5).
Surface: No nicks, indentations or other defects that can be seen without magnification (IEC 61089 Clause 5.3).

A1 Designation and Stranding

Number of Wires	Aluminium Layers Around the Centre Wire	Code Numbers Listed	Example Designation
7	1	10 to 63	40-A1-7
19	2	100 to 250	250-A1-19
37	3	315 to 560	500-A1-37
61	4	630 to 1000	800-A1-61
91	5	1120 to 1500	1250-A1-91

The sizes above are those given in Annex D of IEC 61089, which the standard recommends for new line designs. Sizes and strandings outside this list may be supplied by agreement between purchaser and supplier, in which case the relevant requirements of IEC 61089 still apply (IEC 61089 Clause 5.2). Dimensions, masses, rated strengths and resistances for every listed size are given in the TDS tab.

Typical Applications

Bare overhead distribution lines in urban areas, where spans are short and supports are closely spaced
Overhead lines in coastal regions, where all-aluminium construction resists corrosion well
Distribution feeders where conductivity and low weight matter more than high tensile strength
Replacement or extension of existing lines already designed for A1 conductors

AAC Conductor to IEC 61089 uses a single material, hard-drawn aluminium, in every wire. The table below summarises the construction, tolerance and strength requirements that the standard applies to A1 conductors; dimensions, linear mass, rated strength and d.c. resistance for each code number are listed in the TDS tab.

Technical Characteristics

Applicable Standard	IEC 61089
Standard Scope	Electrical and mechanical characteristics of round wire concentric lay stranded conductors for overhead lines
Conductor Designation	A1, homogeneous hard-drawn aluminium conductor
Wire Material	Round hard-drawn aluminium wires to IEC 889
Stranding	Concentric lay, reversed in successive layers; outer layer right-hand unless ordered otherwise
Number of Wires	7, 19, 37, 61 or 91
Code Number Range	10 to 1500 (aluminium area in mm²)
Lay Ratio	Outer layer 10 to 14; inner layers 10 to 16
Cross-Sectional Area Tolerance	±2% on any sample; ±1.5% on the average of four measurements taken at least 20 cm apart
Diameter Tolerance	±1% for diameters of 10 mm and above; ±0.1 mm for diameters below 10 mm
Linear Mass Tolerance	±2% of the nominal value, conductor without grease
Rated Tensile Strength	Sum of the minimum tensile strengths of all wires
Conductor Breaking Test	No wire fracture below 95% of the rated tensile strength
Aluminium Density Used for Mass	2.70 kg/dm³
Random Lengths	Not more than 5% of the length, with no piece shorter than 50% of the contract length

Ordering Information

Please state the quantity; the code number, designation and stranding (for example 250-A1-19); the length per drum and its tolerance; the drum type and packing method, including any special packaging or lagging; the direction of lay if left-hand is required; and whether wire tests after stranding, conductor breaking strength tests, stress-strain tests or purchaser inspection are required.

Code Number	Area	No. of Wires	Diameter		Linear Mass	Rated Strength	D.C. Resistance at 20 °C
Code Number	Area	No. of Wires	Wire	Cond.	Linear Mass	Rated Strength	D.C. Resistance at 20 °C
	mm²		mm	mm	kg/km	kN	Ω/km
10	10	7	1.35	4.05	27.4	1.95	2.8633
16	16	7	1.71	5.12	43.8	3.04	1.7896
25	25	7	2.13	6.40	68.4	4.50	1.1453
40	40	7	2.70	8.09	109.4	6.80	0.7158
63	63	7	3.39	10.2	172.3	10.39	0.4545
100	100	19	2.59	12.9	274.8	17.00	0.2877
125	125	19	2.89	14.5	343.6	21.25	0.2302
160	160	19	3.27	16.4	439.8	26.40	0.1798
200	200	19	3.66	18.3	549.7	32.00	0.1439
250	250	19	4.09	20.5	687.1	40.00	0.1151
315	315	37	3.29	23.0	867.9	51.97	0.0916
400	400	37	3.71	26.0	1102.0	64.00	0.0721
450	450	37	3.94	27.5	1239.8	72.00	0.0641
500	500	37	4.15	29.0	1377.6	80.00	0.0577
560	560	37	4.39	30.7	1542.9	89.60	0.0515
630	630	61	3.63	32.6	1738.3	100.80	0.0458
710	710	61	3.85	34.6	1959.1	113.60	0.0407
800	800	61	4.09	36.8	2207.4	128.00	0.0361
900	900	61	4.33	39.0	2483.3	144.00	0.0321
1000	1000	61	4.57	41.1	2759.2	160.00	0.0289
1120	1120	91	3.96	43.5	3093.5	179.20	0.0258
1250	1250	91	4.18	46.0	3452.6	200.00	0.0231
1400	1400	91	4.43	48.7	3866.9	224.00	0.0207
1500	1500	91	4.58	50.4	4143.1	240.00	0.0193

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Type Tests

In accordance with IEC 61089 Clauses 5.5.5 and 6.5.4, the method used to joint aluminium wires is shown to reach the required joint strength, either by recent test results or by carrying out the tests.
In accordance with IEC 61089 Clauses 6.5.1 and 6.5.2, stress-strain curves are supplied when the purchaser requests them, and stress-strain tests are performed by the method of Annex B when agreed at the time of order.
In accordance with IEC 61089 Clause 6.5.3, where a breaking strength test is required, the conductor withstands at least 95% of its rated tensile strength without any wire fracturing, using a tensile machine accurate to ±1%.
In accordance with IEC 61089 Clause 6.4.3, conductor samples for tensile and stress-strain tests are at least 400 times the conductor diameter long and in no case shorter than 10 m.

Sample Tests

In accordance with IEC 61089 Clauses 6.2.2 and 6.4.1, aluminium wires are sampled before stranding and tested to IEC 889.
In accordance with IEC 61089 Clause 6.6.1, the aluminium area is calculated from micrometer measurements of the wire diameters and stays within ±2% of nominal on any sample and ±1.5% on the average of four measurements.
In accordance with IEC 61089 Clause 6.6.2, the conductor diameter is measured between the closing die and the capstan as the mean of two readings at right angles, and meets the tolerance of ±1% or ±0.1 mm.
In accordance with IEC 61089 Clause 6.6.3, the linear mass is determined with apparatus accurate to ±0.1% and is within ±2% of the nominal value.
In accordance with IEC 61089 Clause 6.6.4, when required, wires taken from the stranded conductor reach at least 95% of the stress required before stranding, tested at a jaw separation rate of 25 mm to 100 mm per minute.
In accordance with IEC 61089 Clauses 6.6.5 and 6.6.6, the surface condition is checked against Clause 5.3, and the lay ratio and lay direction of each layer are checked against Clause 5.4.

Inspection, Acceptance and Marking

In accordance with IEC 61089 Clause 6.3, sample-test specimens are drawn at random from the outer ends of 10% of the conductor drums, while every drum has its surface inspected before lagging.
In accordance with IEC 61089 Clause 6.7, tests and inspection take place at the production plant before shipment unless otherwise agreed, and a purchaser’s inspector may witness them.
In accordance with IEC 61089 Clause 6.8, failure of any test specimen is grounds for rejecting the lot it represents, after which each drum in the lot may be tested once and compliant drums resubmitted.
In accordance with IEC 61089 Clause 7.2, each package is marked with gross, net and tare mass, length and designation, together with the purchase order number and shipping marks on the outside.

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