ECS Electrical Wiring and Cable Management 2 — Questions and Answers
Question 1: What type of cable is most suitable for use in a zone where mechanical damage is a risk, such as buried directly in the ground?
- Standard twin-and-earth PVC cable
- Steel wire armored (SWA) cable (Correct answer)
- Flexible cord
- Single-core unsheathed cable
Correct answer: Steel wire armored (SWA) cable
Steel wire armored (SWA) cable has a protective steel wire layer that resists mechanical damage, making it ideal for direct burial or exposed runs.
Question 2: When running cables through fire-rated walls or floors, what must be installed to maintain the fire rating?
- Cable glands
- Intumescent fire-stopping materials (Correct answer)
- PVC grommets
- Standard foam sealant
Correct answer: Intumescent fire-stopping materials
Intumescent fire-stopping materials expand when exposed to heat, sealing cable penetrations and restoring the fire resistance of the wall or floor.
Question 3: What is the correct action if a cable is found to have damaged insulation during an installation?
- Wrap with standard electrical tape and continue
- Replace the cable or cut out the damaged section and use an approved joint (Correct answer)
- Leave it if the damage is minor
- Cover with duct tape temporarily
Correct answer: Replace the cable or cut out the damaged section and use an approved joint
Damaged insulation must be properly repaired by replacing the cable or using an approved enclosure joint — tape alone is not an acceptable permanent repair.
Question 4: How should cable terminations be made to ensure a reliable and safe connection?
- By twisting conductors together and applying tape
- By using appropriate terminals or connectors with conductors fully inserted and correctly torqued (Correct answer)
- By soldering all connections regardless of terminal type
- By leaving a small loop of conductor exposed for visual inspection
Correct answer: By using appropriate terminals or connectors with conductors fully inserted and correctly torqued
Correct terminations require conductors to be fully seated in approved terminals and tightened to the manufacturer's specified torque to ensure reliable contact.
Question 5: What is the purpose of cable identification sleeving at termination points?
- To improve the aesthetic appearance of the installation
- To clearly identify conductors for safe maintenance and fault-finding (Correct answer)
- To add mechanical protection to the conductor
- To reduce the cable's resistance
Correct answer: To clearly identify conductors for safe maintenance and fault-finding
Cable identification sleeving ensures conductors are correctly identified at terminations, preventing incorrect connections during maintenance or modification.
Question 6: Which factor is most critical when selecting a cable for a specific application?
- The cable manufacturer's brand reputation
- The cable's current-carrying capacity, voltage rating, and environmental suitability (Correct answer)
- The color of the cable sheath
- The country where the cable was manufactured
Correct answer: The cable's current-carrying capacity, voltage rating, and environmental suitability
Cable selection must consider current-carrying capacity, voltage rating, and environmental factors such as temperature, moisture, and mechanical stress to ensure safe operation.
ECS Electrical Wiring and Cable Management 2
What type of cable is most suitable for use in a zone where mechanical damage is a risk, such as buried directly in the ground?