What Is a Single Core Cable?
A single-core cable is a cable that has only one core wire inside.
In most cases, electrical circuits must be balanced. In a single-phase circuit, the current in one phase must be equal to the current in the other phase, requiring two or more cables. Also, in a 3-phase circuit, the sum of the currents in the three phases must be equal. Therefore, in most cases, a single-core cable is of no use, and two or more cables must be used together to form an electric circuit.
Uses of Single Core Cable
There are two main uses for single-core cable:
As a ground wire: A ground wire is a cable that is connected to a grounding pole buried in the earth, and the resistance between it and the earth is kept below 100 ohms. No current flows through the ground wire when a balanced circuit is established. In the event of a wiring or equipment malfunction, a ground-to-ground voltage applied to the equipment may cause an electric shock. Therefore, current is allowed to flow to the ground wire to ensure safety. A single ground wire is used for the purpose of passing current to the earth.
As a power circuit: As mentioned above, two or more wires are generally used in combination for power purposes.
Principle of Single Core Cable
Single-core cable has the same structure as a multi-core cable.
It has an outer sheath and a protective sheath to protect the core wire. The sheath can be made of various materials depending on the application. For low-voltage circuits, inexpensive vinyl is used as the protective sheath.
Single-core cable has excellent heat dissipation performance due to the large surface area of the single core. Therefore, they are mostly used to handle high currents. To improve heat dissipation performance on cable racks and in culverts, cables are not stacked on top of each other but are piled flat whenever possible. A single-core cable used for extra-high voltage distribution lines may also have insulating oil or refrigerant circulating inside to improve heat dissipation.
Single-core coaxial cable may also be used as a cable for cameras. In this case, a shield insulated from the core wire covers the single-core cable, and the core wire and shield are used like a two-core cable. This was once the mainstream usage for analog image signals but is now being replaced by digital signals such as LAN.