Conductor Stranding Constructions

Different Types of Conductor Strandings

Bunch Stranding	Unidirectional Concentric Unilay Stranding

Rope Stranding	Concentric Equilay Stranding

Bunch Stranding: This type of stranding has any number of strands bunched together and twisted in the same direction. This is a reliable construction but doesn't have as high-quality extrusion as other constructions. This method is the lowest costing or cheapest type of stranding that's currently available.

A similar construction called smooth bunch stranding has helped solve major issues by arranging the strands in a geometric configuration.

Unidirectional Concentric: This stranding configuration has multiple layers of helically laid strands with the same direction of lay. The lay lengths also increase with every succeeding layer.

Unilay: This stranding configuration has multiple layers of helically laid strands with the same direction of lay. This stranding also has the same lay length as all succeeding layers.

True Concentric: A single central strand that is surrounded by layers of helically laid strands. Every layer has a reversed lay direction with increasing lay lengths for every succeeding layer.

Equilay: A single central strand that is surrounded by layers of helically laid strands. Every layer has a reversed lay direction with the same lay lengths for every layer.

Rope: A rope standing is any type of stranding (Bunch, Unicentric, etc.) grounded into a large cable. This construction is used in order to create a very flexible conductor.

Stranding Class Uses
Concentric-lay Conductors
Class B	Power cables.
Class C	Power Cables where more flexible stranding than B class is required.
Class D	Extra flexible stranding, typically used in power cables.
Rope-lay & Bunch stranded Conductors
Class G	All types of portable cables.
Class H	Any cable where extreme flexibility is essential.
Class I	Motor leads and apparatus cables.
Class K	Stationary service cables composed of 30 AWG copper wires.
Class M	Constant service cables composed of 34 AWG copper wire.

Copper Conductor & Stranding Data

				Concentric Strand					Rope Lay
				Concentric Strand					-		Bunch Strand
Approx. O.D.	Pounds /1000 ft	Circular Mils	Size AWG /CM	Class AA	Class A	Class B	Class C	Class D	Class G	Class H	Class K30 AWG (0.010”)	Class M34 AWG (0.0063”)
0.0050	0.0757	25.00	36
0.0056	0.0954	31.52	35
0.0063	0.1203	39.75	34
0.0071	0.1517	50.13	33
0.0080	0.1913	63.21	32
0.0089	0.2413	79.70	31
0.0100	0.3042	100.5	30
0.0113	0.3836	126.7	29
0.0126	0.4837	159.8	28
0.0142	0.6100	201.5	27
0.0159	0.7692	254.1	26
0.0179	0.9699	320.4	25
0.0201	1.2230	404.0	24
0.0226	1.5420	509.5	23
0.0254	1.9450	642.4	22
0.0285	2.4520	810.1	21
0.0363	3.1540	1,020	20			7	19				10	26
0.0456	5.0150	1,620	18			7	19				16	41
0.0576	7.9740	2,580	16			7	19				26	65
0.0726	12.680	4,110	14			7	19	37	49		41	104
0.0915	20.160	6,530	12			7	19	37	49		65	168
0.1160	32.060	10,380	10			7	19	37	49		104	259
0.1600	40.420	13,090	9			7	19	37	49	133
0.1460	51.000	16,510	8			7	19	37	49	133	168	420
0.1840	80.900	26,240	6			7	19	37	49	133	266	665
0.2320	129.00	41,740	4	3	7	7	19	37	49	133	420	1,064
0.2600	162.00	52,620	3	3	7	7	19	37	49	133	532	1,323
0.2990	205.00	66,630	2	3	7	7	19	37	49	133	665	1,666
0.3320	259.00	83,690	1	3	7	19	37	61	133	259	836	2,107
0.3730	326.00	105,600	1/0	7	7	19	37	61	133	259	1,064	2,646
0.4190	411.00	133,100	2/0	7	7	19	37	61	133	259	1,323	3,325
0.4700	518.00	167,800	3/0	7	7	19	37	61	133	259	1,666	4,256
0.5280	653.00	211,600	4/0	7	7	19	37	61	133	259	2,107	5,320
0.5750	772.00	250,000	250,000	12	19	37	61	91	259	427	2,499	6,384
0.6300	925.00	300,000	300,000	12	19	37	61	91	259	427	2,989	7,581
0.6810	1080.0	350,000	350,000	12	19	37	61	91	259	427	3,458	8,806
0.7280	1236.0	400,000	400,000	19	19	37	61	91	259	427	3,990	10,101
0.8130	1542.0	500,000	500,000	19	37	37	61	91	259	427	5,054	12,691
0.8930	1850.0	600,000	600,000	37	37	61	91	127	427	703	5,985	14,945
0.9980	2316.0	750,000	750,000	37	61	61	91	127	427	703	7,581	18,788
1.1520	3086.0	1,000,000	1,000,000	37	61	61	91	127	427	703	10,101	25,193