Monday, February 27, 2012

Wall Plate Jack Considerations | Modular Wall Plates



Modular wall plates are the most common type of wall plate in use for data cabling because they meet the various ANSI/TIA and NEC standards and codes for quality data communications cabling. So modular wall plates have the widest variety of jack types available. All the jacks available today differ based on a few parameters, including the following:
  • Wall plate system type
  • Cable connection
  • Jack orientation
  • ANSI/TIA-568-C.2 and -C.3 wiring pattern

Wall Plate System Type

Remember how the type of wall plate you use dictates the type of jacks for that wall plate? Well, logically, the reverse is also true. The interlocking system that holds the jack in place in the wall plate differs from brand to brand. So, when you pick a certain brand and manufacturer for a jack, you must use the same brand and manufacturer of wall plate.

Cable Connection

Jacks for modern communication applications use insulation displacement connectors (IDCs), which have small metal teeth or pins in the connector that press into the individual wires of a UTP cable (or the wires are pressed into the teeth). The teeth puncture the outer insulation of the individual wires and make contact with the conductor inside, thus making a connection. This process (known as crimping or punching down, depending on the method or tool used) is illustrated in Figure 1.

 
Figure 1: Using insulation displacement connectors (IDCs)
Though they may differ in methods, any connector that uses some piece of metal to puncture through the insulation of a strand of copper cable is an IDC connector.

Jack Orientation

Yes, jack orientation. The individual wall plate systems use many different types of jacks, and some of those systems use jacks with positions other than straight ahead (which is the "standard" configuration). These days, a popular configuration is a jack that's angled approximately 45 degrees down. There are many reasons that this jack became popular. Because it's angled, the cable-connect takes up less room (which is nice when a desk is pushed up tight against the wall plate). The angled connector works well in installations with high dust content because it's harder for dust to rest inside the connector. It is especially beneficial in fiber-to-the-desktop applications because it avoids damage to the fiber-optic patch cord by greatly reducing the bend radius of the cable when the cable is plugged in. Figure 2 shows an example of an angled connector.

 
Figure 2: A faceplate with angled RJ-45 and coaxial connectors
Note 
Angled connectors are found in many different types of cabling installations, including ScTP, UTP, and fiber optic.

Wiring Pattern

When connecting copper RJ-45 jacks for universal applications (according to the standard, of course), you must wire all jacks and patch points according to either the T568-A or T568-B pattern. Figure 3 shows one side of a common snap-in jack to illustrate that the same jack can be terminated with either T568-A or T568-B color coding. (You may want to see the color version of this figure in the color section.) By comparing Table 1 and 2, you can see that the wiring schemes are different only in that the positions of pair 2 (white/orange) and pair 3 (white/green) are switched. If your company has a standard wiring pattern and you wire a single jack with the opposing standard, that particular jack will not be able to communicate with the rest of the network.

 
Figure 3: A common snap-in jack showing both T568-A and T568-B wiring schemes
Table 1 shows the wiring color scheme for the T568-A pattern. Notice how the wires are paired and which color goes to which pin. Table 2 shows the same for T568-B.
Table 1: Wiring Scheme for T568-A 
Pin Number
Wire Color
1
White/green
2
Green
3
White/orange
4
Blue
5
White/blue
6
Orange
7
White/brown
8
Brown
Table 9.3: Wiring Scheme for T568-B 
Pin Number
Wire Color
1
White/orange
2
Orange
3
White/green
4
Blue
5
White/blue
6
Green
7
White/brown
8
Brown

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