N10-009 Question 179
Single answer2.4 Explain important factors of physical installations.A network technician is installing copper Ethernet cabling for several desktop workstations in a manufacturing area. The cable pathway must pass near fluorescent lighting, electric motors, and high-voltage power lines used by industrial equipment. Management wants the installation to minimize network interference without requiring fiber at every desk. Which action is the BEST choice for this installation?
- A
Install shielded twisted pair (STP) cabling and ensure the shielding is properly grounded according to manufacturer and site standards
- B
Install unshielded twisted pair (UTP) cabling and bundle it tightly alongside the power lines to simplify cable management
- C
Use plenum-rated UTP cabling because plenum jackets are designed to reduce electromagnetic interference from nearby machinery
- D
Use a crossover cable for each workstation connection to compensate for electromagnetic interference on the cable run
Show answer and explanation
Correct answer: A
Explanation
This question tests practical knowledge of physical installation factors, especially EMI considerations in industrial settings. For copper Ethernet in electrically noisy environments, shielded cabling is a common best practice when fiber is not being deployed to endpoints. Proper grounding is critical for shield effectiveness. In addition, installers should avoid routing copper data cables parallel and too close to power circuits, transformers, fluorescent lighting ballasts, and motors when possible. Industry best practices reflected in TIA/EIA structured cabling guidance and manufacturer installation documentation emphasize both cable type selection and proper pathway separation. Plenum rating relates to fire code and air-handling spaces, not EMI protection, and crossover cables address pinout compatibility, not interference.
- A. Correct.
Correct. In environments with significant electromagnetic interference (EMI), such as areas near motors, fluorescent lighting, and high-voltage electrical systems, STP is often the best copper-cabling choice because the shielding helps reduce interference. However, STP must be properly grounded to work effectively; otherwise, the shielding may not provide the intended protection and can even introduce issues. This is a practical physical-installation consideration for industrial environments.
- B. Incorrect.
Incorrect. UTP is more susceptible to EMI than STP, and running data cabling tightly alongside power lines increases the chance of interference. Good installation practice is to maintain appropriate separation between data and electrical cabling rather than bundling them together. A technician might choose this option for convenience, but it conflicts with cabling best practices.
- C. Incorrect.
Incorrect. Plenum-rated cable refers to the fire-safety characteristics of the cable jacket and is required in certain air-handling spaces by building code. It does not exist to mitigate EMI. This distractor targets the common misconception that specialty jacket ratings also improve signal shielding.
- D. Incorrect.
Incorrect. A crossover cable changes transmit/receive pinouts for certain Ethernet connections; it does not mitigate EMI. Modern devices also commonly support auto-MDI/MDIX, reducing the need for crossover cables in many cases. Someone unfamiliar with physical-layer interference might confuse link-type problems with environmental cabling problems.