Understanding Electric Cables and Their Different Applications

17 April 2019

Electric cables carry current. In the metallic conductors, a certain amount of material resistivity attenuates the current, so an imperceptible heating effect occurs as the voltages and currents flow against the resistive wires. That’s just basic Ohms Law in action. It’s a simple description of a much more complex principle. Let’s add another layer of detail to the issue. Then, with the theory out of the way, it’s applications time.

Electric Cables Are Insulated

Even more obvious than Ohms Law, electric wires are rarely exposed. They’re generally coated in an insulating plastic, which is colour coded. Otherwise, the wires could cause a nasty electrical shock. The live conductor is coloured brown or red, the neutral line is black, and the earth is green or green-yellow. Then those wires are wrapped in a second, all-encompassing layer of insulating plastic. There are, of course, alternative solutions. Individually coated wires can travel safely in plastic or metal conduits or trunking. When wiring goes underground, the conventions change significantly. Down there, as well as a thick wrapping of rubberized plastic, steel-wire-armoured strands protect the wiring from mechanical damage.

Selecting the Insulator Grade

While still thinking about electrical laws, the subject turns back towards electrical resistivity. Some metals are simply better at conducting current than others. Gold is a superior conductor, but its rare nature keeps it confined to small contact points within electronic circuit boards. Copper is the preferred conductor material. It’s a good current carrier and a malleable metal. That means it’ll bend easily when packed inside a restricted area. Overhead wires also loop easily so that they’ll expand and contract as weather conditions vary.

Electric Wiring Applications

For the best available copper, there are a handful of application-relevant factors to weigh. Wider diameter cables conduct more power, for instance. Stranded and solid wires suit different applications, that’s another rule. Finally, oxygen-free copper alloys are selected as low resistivity lines. They reduce power loss effects while delivering current more efficiently than other alloy types. On to applications, there are windings inside electric motors. To save space the strands are coated in a special insulating varnish, not plastic. Control panels are littered in loops of multi-coloured wires. At least that’s how it would look if it weren’t for an expert electrical technician’s wire tidying skills. Car interiors are the same, as are marine vessels, electrical distribution boards, and power instrumentation assemblies.

All of these varying cable profiles alter as the applications change. In a home, a single-phase brown or red wire is accompanied by a blue neutral and a green-yellow earth conductor. In industry, power needs alter, so three-phase electricity calls upon thick diameter electric wiring. Data pathways and communications circuits occupy the other end of the scale. Thin and stranded wires conduct tiny digital signals here, and they need special signal shields to prevent all sorts of noise from obliterating that clean waveform.

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