The Complete Handbook of Cables

Chapter 1: Understanding Cables

Cables are a medium for delivering something from one place to another: electrical current, data signals, audio, video, light. At the most basic level, a cable is a conductor—usually copper or aluminum—wrapped in insulation and often surrounded by shielding, all contained within a jacket that protects against mechanical damage and environmental exposure. But that simple description masks the physics and real-world constraints that separate a cable that works reliably from one that fails under load, corrodes over time, or creates safety hazards.

To understand cables, start with why they exist. A power cable running 20 amps across 100 feet of distance cannot be bare copper wire; the resistance of the conductor causes voltage drop, heat loss, and fire risk. A network cable in a factory floor surrounded by high-amperage motor circuits cannot be shielded the same way as one in an office. An outdoor cable exposed to UV radiation and temperature swings from -40°F to 140°F cannot use the same insulation as an indoor, temperature-controlled environment. Cables are solutions to specific problems: delivering current or signal safely, reliably, and within acceptable loss over a defined distance under defined conditions.

The Basic Cable Structure

A cable consists of three essential layers: the conductor, the insulation, and the jacket. In many cases, a fourth layer—shielding—sits between insulation and jacket.

The conductor is the part that carries current or signal. In power cables, this is almost always copper or aluminum; copper is the standard because it has lower electrical