cable core
Central part or the innermost part of a power cable which carries electric current and is surrounded by various layers of insulation.
cable core: the conductor that actually carries power
The cable core is the electrical conductor at the heart of a power cable, made from copper or aluminium, that carries the working current from source to load. It is the only part of the cable that must conduct electricity; everything surrounding it exists to protect that core from damage, moisture, and contact with other conductors or people.
Most cable cores are stranded rather than solid. A stranded core comprises many thin wires twisted together, which makes the cable flexible enough to route through conduit, around equipment, and in and out of junction boxes without cracking. The cross-sectional area of the core, measured in square millimetres, determines the cable's current-carrying capacity or ampacity. A 10 mm² copper core will safely carry roughly 50 amps at 70 degrees Celsius under normal conditions, though this rating depends on the insulation type and ambient temperature.
Copper dominates in power cables because of its superior conductivity and reliability, but aluminium cores appear in larger cables above 50 mm² because they are cheaper and lighter. Aluminium is less conductive per unit volume, so an aluminium core must be larger than a copper one to carry the same current. The boundary between them shifts depending on voltage, distance, and cost of materials at the time of manufacture.
Core failures and protection
Cable core damage usually results from mechanical stress, corrosion, or overheating. Moisture entering the cable through damaged outer jackets will eventually corrode copper or form oxides on aluminium, increasing resistance and generating heat. Overloading a cable past its rated ampacity causes the core itself to heat and degrade the surrounding insulation, which then fails prematurely. Flexing cables repeatedly or running them over sharp edges can fracture stranded wires, raising resistance until the cable fails or catches fire.
The core sits immediately inside the primary insulation layer, usually polyvinyl chloride (PVC) or cross-linked polyethylene (XLPE). In multi-core cables (those with two or three conductors for three-phase or neutral circuits), each core has its own insulation layer, and the entire bundle is then wrapped in a common outer sheath. The name 'core' reflects the sense of something central and essential, the actual working part around which all protective engineering is built.