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Conductor Stranding Constructions

Different Types of Conductor Strandings

  

Bunch Stranding Unidirectional Concentric Unilay Stranding
Conductor Bunch Stranding Unidirectional Concentric Unilay Stranding
Rope Stranding Concentric Equilay Stranding
Conductor 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
- 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