1. What is the difference between enhanced Category 5e cable rated for 400 MHz and Category 6 cable rated for 250 MHz?
Category 5e requirements are specified up to 100 MHz. Cables can be tested up to any frequency that is supported by the test equipment, but such measurements are meaningless without the context of applications and cabling standards. The Category 6 standard sets minimum requirements up to 250 MHz for cables, connecting hardware, patch cords, channels and permanent links, and therefore guarantees reasonable performance that can be utilized by applications.
2. Why did all Category 6 cable used to have a spline, and now is offered without one?
Some Category 6 cable designs have a spline to increase the separation between pairs and also to maintain the pair geometry. This additional separation improves NEXT performance and allows Category 6 compliance to be achieved. With advances in technology, manufacturers have found other ways of meeting Category 6 requirements. The bottom line is the internal construction of the cable does not matter, so long as it meets all the transmission and physical requirements of Category 6. The standard does not dictate any particular method of cable construction.
3. Is there a limitation on the size of bundles one can have with Category 6? Can you have 200-300 and still pass Category 6?
There is no limit imposed by the standards on the maximum number of Category 6 cables in a bundle. This is a matter for the market and the industry to determine based on practical considerations. It should be pointed out that after six or eight cables, the performance in any cable will not change significantly since the cables will be too far away to add any additional external (or alien) NEXT.
4. If we use a Cat 5e RJ45 connector and connect it to a CAT 6 UTP cable, will the installation be CAT 5e or CAT 6?
By definition (of the standard), it will be a Cat 5e channel. The actual performance will probably be somewhat better, but nowhere near CAT 6 requirements. Of course, you can set up a channel using any components and measure it using a CAT 6 (level III) compliant tester, and if it passes, it is CAT 6 performance compliant. It would not be standards compliant however, because the components have requirements in and of themselves to assure interoperability with other CAT 6 components.
5. I am receiving a lot of questions about a multipair CAT 6, is any specification available for this cable? Does it exist?
Multipair cables are not specifically called out in ANSI/TIA-568-B.2-1, the Category 6 standard. See section 6.1.2 below which recognizes 4-pair cables for backbone applications. Additionally, hybrid cables consisting of multiple 4-pair cables in a single jacket or binder may also be used for both horizontal and backbone applications provided that the requirements of section 6.1.3 below are met. Since Category 6 cabling is based on a 4-pair, 4-connector, 100 meter channel, multipair cables are implemented as hybrid cables consisting of 4-pair sub-units.
6.1.2. Backbone cable section, ANSI/TIA-568-B.2-1 Category 6 standard. Four-pair 100. UTP and ScTP cables are recognized for use in Category 6 backbone cabling systems. The cable shall consist of 22 AWG to 24 AWG thermoplastic insulated solid conductors that are formed into four individually twisted-pairs and enclosed by a thermoplastic jacket. The cable shall meet all of the mechanical requirements of ANSI/ICEA S-80-576 applicable to four-pair inside wiring cable for plenum or general cabling within a building. In addition to the applicable requirements of ANSI/ICEA S-90-661-1994, the physical design of backbone cables shall meet the requirements of clauses 4.4.3.1 to 4.4.3.6 of ANSI/TIA/EIA -568-B.2. NOTE: Additional requirements for 100 ScTP cables are located in annex K of ANSI/TIA/EIA-568-B.2. 6.1.3 Bundled and hybrid cable, ANSI/TIA-568-B.2-1 Category 6 standard. Bundled and hybrid cables may be used for horizontal and backbone cabling provided that each cable type is recognized (see clause 6.1.1 of this standard and clause 4.4 of ANSI/TIA/EIA-568-B.1) and meets the transmission and color-code specifications for that cable type as given in ANSI/TIA/EIA-568-B.2, ANSI/TIA/EIA-568-B.3, and clause 7 of this standard. Additionally, for all frequencies from 1 MHz to 250 MHz, the total power sum NEXT loss for any disturbed pair from all pairs internal and external to that pair's jacket within the bundled or hybrid cable shall not exceed the values determined using equation (1). Calculated power sum NEXT loss limit values that exceed 65 dB shall revert to a limit of 65 dB.
