Guidelines on How to Choose the Right Kind of Electrical Cable

23 April 2019

First time off the blocks, cable selection guidelines were explored. Basic precepts were outlined. A framework of sorts was constructed so that you could recognize the electrical factors and material properties that affected a current as it was being transported. Now that some of the basic groundwork has been laid, you’re moving onward and upward. Here’s where you’ll be introduced to the right electrical cable type for any particular application.

Selection Guidelines: Electrical Cable Sizing

Assuming the wiring is high-quality copper, it’ll exhibit a fixed measure of material resistivity. The only way to alter its current transporting characteristics is to change the cross-sectional area of the wiring. By increasing the size of the conductors, they’ll carry more current. With that basic concept in mind, rolls of building wiring are typically available in sizes that vary between 1-mm and 16-mm. For heavy-duty applications, expect the conductors to thicken significantly. A 95-mm cross-section is not unusual in such applications.

Selecting Multi-Phase Wiring

Specially developed three-phase wiring systems provide extra horsepower. They’re also the more energy-efficient option when compared against a similar single-phase solution. Using Alternating Current (AC), three waveforms combine to provide additional electromagnetic power. Three phase cables are used in transformers, substation switchgear, and in motors to economically deliver a given amount of electrical energy.

Electronic Cabling Requirements

Less about power and more about signal-to-noise ratios, such cable types carry clean digital or analogue signals. Audio-visual information, communications or telephony data packages, instrumentation wiring, and automotive electrics, all of these circuit types use some form of signal transmission technology. As such, the data requires shielding. Special coaxial strands or braided wire linings serve as interference blocking barriers.

How To Select Conventional Electrical Wiring

Skipping past thin signal carrying wires, you see a standard roll of building wiring. It’s separated into a group of individual conductors, in which case the wires will enter a tubular conduit or a squared-off trunking run. If the wiring is designed to be concealed behind a plasterboard wall, its three conductors will be contained inside a cable flat, with its plastic-joined insulation adding further strength to the cable roll as it extends through the building framework. Again, cross-section considerations provide safe current-carrying capacity. Otherwise, if too narrow, the wiring could overheat and cause a fire.

Even the copper conductors change shape, dependent on the job at hand. If the electrical wiring runs are long and straight, solid strands are the go-to conductor type. However, should the wires bend and flex, then multi-stranded copper conductors are favoured over the solidly graded variety. Finally, for HVAC applications, high-temperature sheathing resistance and/or impact resistance strength become relevant selection factors.

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