ANSI/ TIA/EIA-568-B.2 has been replaced with ANSI/TIA-568-C.2.
You will find that the values in this ANSI/TIA-568-C.2 standard match those in the DTX and DSP CableAnalyzers.
The following is kept only as a record of history for interested customers.
In ANSI/ TIA/EIA-568-B.2, you would find a table detailing the test limits for Category 5e Patch Cords.
Table 25 -Example category 5e cord NEXT loss limits using the test head in clause F.6
The limits were derived using the same jack used for Category 5. There was concern about doing this at the time. As a result, the following text was added to section 22.214.171.124 of ANSI/ TIA/EIA-568-B.2:
NOTE - The test jack described in annex J was designed to test category 5 modular plug,
work area, and equipment cords and should be adequate for category 5e modular
plug cord qualification. The development of a specific test jack for category 5e
modular plug, work area, and equipment cords is under study.
Table 25 above is derived from the following formulae:
where the NEXT local, 100 MHz and NEXT remote, 100 MHz is stated as being 41 dB.
As indicated in section 126.96.36.199, a new test jack was selected after the standard was approved. This new test jack has a NEXT local, 100 MHz and NEXT remote, 100 MHz of 47 dB. As a result, the test limits for patch cord testing against this new test jack are different to that in Table 25. The 41 dB used for NEXT local, 100 MHz and NEXT remote, 100 MHz in the above formula is replaced with 47 dB, which gives us the following table:
Category 5e cord NEXT loss limits using a test jack with a mated NEXT of 47 dB @ 100 MHz
These values are found in the latest code for the DSP-4x00 and DTX CableAnalyzers. The new value of 47 dB has been used in the revision of ANSI/TIA/EIA-568-B, ANSI/TIA-568-C.2 published in August 2009.