Question by André Hanekom posted 28 Jul 2005
| UTP Solid or stranded |
|I need some advise. I know the max length for UTP CAT5 is 100meters, does that apply to both the Solid and Stranded type? Or is the one type better for "fly leads" and the other one for installing network points? Thanks for the help!|
Answer by Joseph Golan posted 28 Jul 2005
The 100 meter rules for a channel includes 90 meters of solid conductor cable for the link in most cases with the remaining 10 meters to be equipment/patch cords which are typically stranded construction.
As stranded cable has a higher attenuation, the 90 meter link would have to be shortened to make up for the additional loss. There is a formula for knowing the maximum length of the link depending on the length of stranded cable required, as quoted from the TIA/EIA-568-B.1 standards:
188.8.131.52 snip..... Based upon insertion loss
considerations, the maximum length shall be determined according to:
C = (102 - H)/(1+D) (1)
W = C - T
C is the maximum combined length (m) of the work area cable, equipment cable, and patch cord.
H is the length (m) of the horizontal cable (H + C
D is a de-rating factor for the patch cord type (0.2 for 24 AWG UTP/24 AWG ScTP and 0.5 for
26 AWG ScTP).
W is the maximum length (m) of the work area cable
T is the total length of patch and equipment cords in the telecommunications room.
End of Quote
Basically in a nutshell, it says for 24 AWG stranded cable, length shall not exceed 72 feet, quite a reduction. My reccommendation is to always use solid conductor cable for your installed wiring.
Joseph Golan, RCDD
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