Wiring Harness News Sep-Oct 2021 - Page 36

In every issue of Wiring Harness News , Anixter will bring you informative articles about wire and cable technology .
Conductor Resistance

In one of our previous Wire Wisdoms , “ Conductors – The Electron Superhighway ,” we discussed different size conductors and the reasons for their existence . One of the principal reasons for having different size conductors is due to resistance . Resistance is defined as the opposition to the flow of electrical current through a conductor . It ’ s important to point out that conductivity and resistivity ( the property that determines final resistance ) are inversely proportional . The more conductive something is , the less resistance it will have . This Wire Wisdom will examine how resistance affects wire and cable .

All Objects Have Resistance
The best conductors in the world , excluding superconductors , have some resistance . Even though most people believe gold is the best conductor because of its common use in high-end consumer products , it is actually silver ( gold is used on these products because it does not corrode easily and can be left untreated on a shelf for months or years ). Electricity can flow through nonmetals as well ( e . g ., wood , plastic , rubber and glass ), but resistance is much lower in metals such as silver and gold . Even though gold and silver have low resistances , they are too expensive in most cases to be applied in any form other than plating .
Copper is the Most Common Conductor
In the late 1700s , copper was found to be a more cost-effective option than silver . Its low resistance , wide availability and relative low cost launched it to the top of the preferred conductor charts . The amount of copper products consumed in the USA last year could make a 12 AWG wire long enough to make 140 round trips to the moon .
Aluminum is another widely used material to conduct electricity . With conductivity 62 percent of copper , it has a slightly higher resistance than gold but with a relatively low weight , given its level of resistance . It is also cheaper than copper on a pound-forpound basis . However , more conductor volume is required than copper , which means it is not as ideal for small applications with space constraints .