Difficulty: Medium
Correct Answer: 3 meters
Explanation:
Introduction / Context: TIA/EIA-568 structured cabling guidelines define a 100 m maximum channel length for copper twisted-pair Ethernet (typically 90 m permanent link plus up to 10 m of patch cords). Within that budget, a common design practice is to allocate a short work-area patch from the outlet to the device, ensuring margin for the telecom room patch cords as well.
Given Data / Assumptions:
Concept / Approach: A widely used rule-of-thumb assigns roughly 5 m total for patching (for example, 2 m in the telecom room and up to 3 m in the work area). Keeping the work-area patch around 3 m maintains compliance and preserves flexibility for moves/adds/changes without exceeding the 100 m channel maximum.
Step-by-Step Solution:
Start with the 100 m channel budget.Reserve ~90 m for the permanent link.Allocate remaining ~10 m to patch cords: commonly ~2 m TR + ~3 m work area, leaving additional slack for jumpers.Therefore, 3 meters is the typical recommended maximum for the wall-to-PC patch.Verification / Alternative check: Many enterprise cabling standards and vendor design guides present examples with 90 m permanent links and 3 m end-user cords to maintain channel performance.
Why Other Options Are Wrong:
1 meter: feasible but overly restrictive; 3 m is the common recommendation.6 or 9 meters: risk exceeding the 100 m channel when combined with other patching.None of the above: incorrect because 3 meters is the accepted practice.Common Pitfalls: Confusing permanent link limits with patch cord allowances, or forgetting both ends’ patching must fit within the 10 m budget.
Final Answer: 3 meters.
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