Copyright Goodheart-Willcox Co., Inc. 80 Networking Fundamentals 1 2 3 4 1 2 3 4 1 3 2 4 1 2 3 4 1 2 3 4 1 2 3 4 A B C Each pair of conductors are straight through. The connection numbers are the same at each end. Normal The blue pair is an example of a reversed pair. Notice how the connections on the right are reversed as compared to the connections on the left. Reversed Pair This is an example of crossed pairs. Take special notice of the green and blue pairs. The blue and green have switched positions. Crossed Pairs This is an example of a split pair. Each of the two pairs of conductors have had its pair split and connected to the other pair position. Split Pair D 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 2 1 3 4 1 2 3 4 1 2 3 4 1 2 3 4 3 4 1 2 1 2 3 4 Figure 2-37 Common wiring errors: reversed pair, crossed pairs, and split pair. The red numbers indicate the errors. A—Normal connection is made. Each conductor is wired to a corresponding connection number. B—Reversed pair. Conductors within the pair reverse their connection at the opposite end of the cable. C— Crossed pairs. Two pairs have switched positions at the opposite end of the cable. D—Split pair. One conductor from each of two pairs have switched positions at the opposite end of the cable. Goodheart-Willcox Publisher Goodheart-Willcox Publisher Figure 2-38 An electronic cable tester is used to check for wiring faults such as crossed pairs, split pairs, and reversed pairs.