62chaokai wrote:
標準和規範的解釋
把迷信剷掉可能比名詞解釋要來的重要的多.
from: TIA/EIA-568-B
1.2 Specification of criteria
In accordance with EIA Engineering Publication, EP-7B, two categories of criteria are specified;
mandatory and advisory. The mandatory requirements are designated by the word “shall”; advisory
requirements are designated by the words “should”, “may” or “desirable” which are used interchangeably in this Standard.
4.5 Stranded conductor cable
This clause contains the transmission requirements for the bulk cable used to construct patch,
equipment, and work area cords. (下略)4.5.1 Mechanical, 4.5.2 Transmission, 4.5.3 Return loss 4.5.4, Insertion loss, 4.5.5 Performance marking
6.3 Mechanical
Cables used to construct patch, work area, and equipment cords should have stranded conductors
and shall meet the requirements of clause 4.5. Stranded conductor cable may be used to increase
flexibility of cords. Cables used for patch cords shall meet the conductor size and color coding
specified in clauses 6.3.1 and 6.3.2, respectively. Twisted-pair conductor lay lengths for 24 AWG or larger stranded conductors shall not exceed 15 mm (0.6 in).
簡單的來說, stranded conductor 僅只是為了 flexibility 的選擇性建議, 如果選用這種 patch cord 則"強制"必須符合一定的電器特性才能使用. (三段要倒著看)
而已目前新的規定來說, 對於線徑的要求已經放棄, 由於合金技術的進步, 許多使用 solid conductor 同樣能達到相當好的 flexibility, 而且具備更好的電器特性, 例如某些 panduit 的"高階"產品.
其實就看這三段大概就清楚為什麼我認為這種事情只是迷信, 僅只是來自於對於"標準"的誤解而已.
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