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