Connecting Hardware and Cable
Connecting Hardware is the physical products used to terminate cable elements at our CD's, BD's, FD's and TO's. The connecting hardware may be for copper cables or fiber cables. The standards require that connecting hardware be capable of meeting the following requirements.

  • terminated cable must be capable of interconnection with jumpers or patch cords
  • a method of identifying cabling for administrative purposes
  • be of a style that permits orderly cable management
  • be accessible for testing
  • have reasonable protection against physical damage
  • provide protection from the ingress of moisture and dust
  • be sufficiently small to allow for high density terminations
  • cater for shielding and earth bonding if needed
This is pretty broad stuff and allows plenty of scope for manufacturers to be innovative in their designs. Hardware manufacturers of Cat 5, 5e or 6 RJ45 sockets must also make a variety of styles for different applications such as mounting the hardware on walls or skirting duct or in wall mounting or for floor mounts or 19" racks or closets etc. These requirements also apply to IDC block termination hardware (e.g. 110 styles) which is another type of recognised hardware. When you look at the evolution of this hardware through Cat 3 to Cat 5e applications you see a very distinctive physical and technological change in these products. Below is a picture that shows the progression of this product from Cat 3 to Cat 6. The early hardware was very ordinary and did not cater for high frequency signals. But as the data rates and cable bandwidth increased the termination hardware had to better match the cable. This was evident in Cat 5 and Cat 5e product with a noticeable introduction of capacitors being built into the printed circuit boards of the hardware. Cat 6 products are just smaller so that the distance from the terminated cable through the socket is as short as possible to mate with the RJ45 plug.



Why capacitive additions? Because the twist rates in the cable went up significantly thus the cable inductance went up also. To balance this more capacitance was needed. Another obvious change in product is the physical distance from the IDC punch down of the wire to the socket contacts. The reason for shortening the socket contacts, that is the physical length of that wire from the cable pair to the contacts was a clear recognition that the wires are no longer twisted as they are in the cable. The significance of having no twists is that the cross talk will increase when we have these parallel wires in the socket.

The wiring standards make it very clear that the manner in which you install and terminate your cables to your hardware is critical to good circuit performance. Here are the key criteria stated in the standards that must be adhered to.
  • elimination of cable stress
  • cable must have no tension, sharp bends and must not be tightly bunched
  • cable minimum bend radius must be met
  • proper cable termination practices shall be met
  • adequate room for cable administration
  • adequate room for equipment interconnects to be met
  • patching management is required
  • marking and colour coding is recommended
  • different cable types must be identified
The minimum bending radius for various cables is listed below. to help you understand the importance of minimum bending radii with copper cables try to relate this analogy to better understand the effects of a high frequency signal on our copper pairs. Think of a fast car trying to travel around a bend in the road. There is a maximum speed at which the car may traverse the bend. Too fast and the car will not make it around the bend. High frequency signals on our cable are similar in that tight bends are a sudden change in the wave guide (our copper pairs). When bends are too tight the HF signal will radiate more and this is a loss of energy. This leads to signal degradation and circuit problems.

Cable Type Minimum Bend Radius
as placed		 Minimum Bend Radius
hauling in tension
UTP 4 pair 4 times cable diameter
@25mm(1 inch)		 8 times cable diameter
@50mm(2 inch)
ScTP 4 pair 4 times cable diameter
@25mm(1 inch)		 8 times cable diameter
@50mm(2 inch)
Fiber
2 or 4 fiber
Intrabuilding		 25mm(1 inch) 50mm(2 inch)
Fiber
Interbuilding		 10 times cable diameter 20 times cable diameter

The maximum pulling tension for 4 pair UTP it is 110 N (25 lbf). Please consult the manufacturers guidelines for other cable types. The effect of stretching a copper UTP cable is to elongate the copper and insulation. This changes the impedance and thus causes additional attenuation, reflections and cross talk. Stretching a fiber cable may simply break fibers. Fiber is pretty strong under longitudinal stress but when dragged around a bend the stress may fracture and break the fibers. You must be careful installing cable, any cable. Here is the preferred colour code and pin assignments to terminate a 4 pair cable in an RJ45 socket.



The recommended type of fiber optic connector is the SC style. This is the square looking fiber connector. Depending on the application this will be single connectors fixed in adaptors or it may be a duplex SC connector. Previous versions of these standards recommended ST connectors. These are the round body connector with a bayonet fitting similar to BNC connections. ST's are still OK to use if the existing site has ST fittings and you wish to maintain consistency throughout your site. The standards don't preclude using other styles especially since many of the newer styles have much smaller form factors. This means you can fit more connectors into less space. The MTRJ seems popular as is the Volition. Most manufacturers of equipment allow you to specify what type of connector you need. As time and equipment progresses you will find more and more equipment only requiring one fiber and one fiber connector as Wavelength Division Multiplexing is becoming more popular. This technique uses say 4 wavelengths in one direction where each wavelength carries say 2.5Gig so that is a total of 10Gig. By using 4 different wavelengths in the reverse direction you could gain another 10Gig so that one fiber will carry 10Gig Full Duplex. This is not a cheap option yet. So the majority of fiber termination will need to be SC connectors, one connector for each direction of data. Below is a picture of SC Simplex and Duplex connectors and adaptors.