Why Ethernet Cables Use Twisted Wires

Engadget said the twisted-pair concept is credited to Alexander Graham Bell and dates to the 1880s, when the cables were used for the first telephone lines in the United States. Decades later, the same arrangement is the industry standard for Ethernet.

The reason is electromagnetism. When electric charges move along a wire, they create a magnetic field around the metal strand. If two wires run parallel, the field from one can impede electricity in the other and slow the signal. Twisting the wires creates an opposing magnetic field that cancels the possible impediment, allowing the signal to travel at peak speed, Engadget said.

Most modern Ethernet cables contain four twisted pairs of copper wires. Depending on how much information is transmitted, not all pairs may be in use at a given time, but all four are active for standards such as gigabit internet, according to the report. A foil coating around the bundled wires helps insulate signals from outside interference, while the twisted pairs prevent the individual wires from interfering with each other, a problem called crosstalk.

Engadget said each of the four pairs is twisted at a different rate. The variation helps ensure that the magnetic field created by each pair does not cause new interference problems for the others. If all pairs were twisted in the same way, side-by-side pairs could suffer the same performance problems as individual wires run in parallel.

Twisted-pair wires are standard for almost any contemporary technology cable, so consumers replacing Ethernet lines at home do not need to seek them out specifically, Engadget said.