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For cables, the swapping is gradual and continuous; that is the two or three conductors are twisted around each other. For communication cables, this is called twisted pair . For overhead power lines or open pair communication lines, the conductors are exchanged at pylons, for example at transposition towers or at utility poles , respectively.
The 20-pair colour code is a colour code used in Australia to identify individual conductors in a kind of electrical telecommunication wiring for indoor use, known as twisted pair cables. The colours are applied to the insulation that covers each conductor. The first colour is chosen from one group of five colours.
Telephone cable containing multiple twisted-pair lines. The primary line constants are parameters that describe the characteristics of conductive transmission lines, such as pairs of copper wires, in terms of the physical electrical properties of the line.
Twisted-pair cabling was invented by Alexander Graham Bell in 1881. [4] By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference. Today, most of the twisted pairs in the world are outdoor landlines, owned and maintained by telephone companies, used for voice service.
Typical values of Z 0 are 50 or 75 ohms for a coaxial cable, about 100 ohms for a twisted pair of wires, and about 300 ohms for a common type of untwisted pair used in radio transmission. Propagation delay is proportional to the length of the transmission line and is never less than the length divided by the speed of light .
The pattern then starts over with the first 25-pair group as white/blue, and continues indefinitely, in multiples of 600 pairs or parts thereof. For example, a 900-pair cable has the first 600 pairs in 24 groups of 25 pairs in a white binder, and the remaining 300 pairs in 12 groups of 25 pairs wrapped in a red binder. [5] [6]
Twist-on wire connectors are a type of electrical connector used to fasten two or more low-voltage (or extra-low-voltage) electrical conductors. They are widely used in North America and several European countries in residential, commercial and industrial building power wiring, but have been banned in some other jurisdictions.
Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair , a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves ...