The outermost layer of wires and cables, typically a rubber or rubber composite sheath, provides insulation and protects the cable from damage.
Cables are categorized as either high-voltage or low-voltage. High-voltage cables also have a layer of resin-like filler inside to provide insulation. In high-voltage cables, this layer is the most important insulation component. Low-voltage cables lack this layer. A ribbon-like material is also wrapped around the cable to secure each core and fill the gaps between them.
