ort and extends the distance over which the sig- nals can travel. A load pot, shown in Figure 3-21, comprises multiple load coils and performs loading for all the cable pairs in a cable that require it. It may also encounter a repeater if it is a digital loop carrier; the repeater receives the incoming signal, now weakened and noisy from the distance it has traveled, and reconstructs it, amplifying it before sending it on its way. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Telephony Chapter 3 One last item of interest: Though we call them telephone poles, the wooden poles that support telephone cables are, in fact, shared among telephone, power, and cable providers, as shown in Figure 3-22. Tele- phony plant is the lowest, followed by cable; power is the highest, high enough that the tallest technician working on a phone or cable problem could not accidentally touch the open power conductors. Normally the telephone company owns the pole and leases space on it to other utilities. As a cable approaches the central office, its pairs are often combined with those of other approaching cables in a splice case (see Figure 3-23) Figure 3-21 A load pot containing load coils Load Pot Figure 3-22 Shared pole for aerial plant Power Cable Telephone Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Telephony Telephony Figure 3-23 Splice cases (two on left, one on right) Figure 3-24 In the cable vault, the large cables shown on the left are broken down into the smaller cables on the right for distribution throughout the office. to create a larger cable. For example, four 250-pair cables may be com- bined to create a 1,000 pair cable, which in turn may be combined with others to create a 5,000 pair cable that enters the central office. Once inside the office the cables are broken out for distribution. This is