Electrical cable
Assembly of wires carrying electric current between devices.
An electrical cable is a bundle of one or more wires that run alongside each other, designed to conduct electric current. These cables link two or more devices, allowing them to exchange electrical signals, power, or both. They are commonly found in building wiring for lighting, power, and control circuits, as well as in long-distance communication (including undersea cables) and bulk power transmission using high-voltage lines.
Physically, a cable consists of one or more conductors, each with its own insulation and sometimes screens, plus individual coverings, assembly protection, and an outer protective layer. To make cables more flexible, wires can be stranded—twisting or braiding smaller wires together into larger ones. Bunching small wires before concentric stranding adds the most flexibility. Copper wires may be left bare or plated with tin, gold, silver, or another metal to resist oxidation, ease soldering, and provide lubrication between strands. Tinning also helped remove rubber insulation in the past. Tight stranding can make a cable extensible, as seen in telephone handset cords.
In the 19th and early 20th centuries, cable insulation was often cloth, rubber, or paper. Today, plastics are standard, except for high-reliability power cables. The first thermoplastic used was gutta-percha, a natural latex, for underwater cables. Polyethylene, the first common man-made plastic for insulation, was invented in 1930 but only became widely available after World War II; a telegraph cable using it was laid across the English Channel after D-Day. Cables can be organized and secured with trunking, cable trays, ties, or lacing, and flexible cables in moving applications may use strain relief devices.
Any current-carrying cable radiates an electromagnetic field and can also pick up energy from surrounding fields. These effects can cause unwanted energy transmission or noise pickup, potentially interfering with equipment or corrupting signals and power. Solutions include keeping cable lengths short, routing them away from trouble, and using specific designs. Shielding, based on the Faraday cage principle, encases the cable in foil or wire mesh, decoupling internal wires from external fields—especially if the shield is grounded. However, simple shielding is less effective against low-frequency magnetic fields, like hum from a transformer. A grounded shield on cables operating at 2.5 kV or more also gathers leakage and capacitive current, protecting people from shock and equalizing insulation stress. Coaxial design, with a circular shield and centered inner conductor, reduces low-frequency magnetic transmission by canceling induced voltages. Twisted-pair cables have two wires twisted together; when the interfering signal’s wavelength is long relative to the twist pitch, alternate wire lengths develop opposing voltages that cancel the interference.
- field
- Electrical engineering
- known_for
- Conducting electric current between devices
- types
- Coaxial, twisted pair, power cable, shielded cable, ribbon cable, armored cable
- materials
- Copper, tin, gold, silver; insulation from gutta-percha, polyethylene, rubber, paper, cloth
- key_feature
- Flexibility improved by stranding wires
Lore & Background
Electrical cables consist of one or more conductors with their own insulations and optional screens, individual coverings, assembly protection, and protective covering. Flexibility can be increased by stranding wires—twisting or braiding smaller individual wires together. Copper wires may be bare or plated with tin, gold, or silver to reduce oxidation and ease soldering. Tinning also provides lubrication between strands and helped remove rubber insulation.
In the 19th and early 20th centuries, cables were often insulated with cloth, rubber, or paper. The first thermoplastic used was gutta-percha, a natural latex, for underwater cables. Polyethylene, invented in 1930, became common after World War II; a telegraph cable using it was laid across the English Channel to support troops following D-Day.
Cables can be secured using trunking, cable trays, cable ties, or cable lacing. Continuous-flex cables in moving applications may use strain relief devices. Fire hazard from grouped cables can be significant; jacket materials can be formulated to prevent fire spread, or fire retardant coatings and noncombustible boxes can be used.
Reader's Guide
Electrical cables are fundamental to modern infrastructure, enabling the transfer of power and signals across devices and distances. Their design addresses practical challenges: shielding, coaxial geometry, and twisted-pair geometry minimize electromagnetic interference. Shielding uses a Faraday cage principle, encasing the cable in foil or wire mesh to decouple internal wires from external fields. Coaxial design further reduces low-frequency magnetic effects by centering the inner conductor within a circular shield. Twisted pairs cancel interference by developing opposing voltages along alternate lengths. Cable types are specialized for applications: coaxial for radio frequency signals, twisted pair for data, power cables for bulk transmission, and ribbon cables for low-voltage multi-wire needs. The choice of materials—copper, tin, gold, silver—affects conductivity, oxidation resistance, and solderability. Insulation evolved from natural materials to plastics like polyethylene, improving durability and performance. Fire protection measures include flame-retardant jackets and noncombustible enclosures. Overall, electrical cables are a critical but often invisible component of electrical systems, balancing conductivity, flexibility, safety, and interference control.
Did You Know?
- Electrical cables may be made more flexible by stranding wires, twisting or braiding smaller wires together.
- The first thermoplastic used for cable insulation was gutta-percha, a natural latex, in the 19th century.
- Polyethylene, invented in 1930, was first used in a telegraph cable laid across the English Channel after D-Day.
- A grounded shield on cables operating at 2.5 kV or more gathers leakage current and protects people from electric shock.
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