--- title: "Wires and cables in industrial building" subject: "Industrial Power Distribution and Illumination" chapter: 3 key: "semester_6/industrial_power_distribution_and_illumination:wires-cables-industrial-building" source: https://www.bctengineer.com/q/semester_6/industrial_power_distribution_and_illumination/wires-cables-industrial-building site: BCT Engineering --- # Wires and cables in industrial building Industrial Power Distribution and Illumination · Chapter 3: Power Carrying Devices - Asked in: 2071 Bhadra, 4 marks - Video: [Industrial Power Cables, LV cables, LT cables, Power cable Types and Markings, Cable classification](https://www.youtube.com/watch?v=KJgHHCXEPEk) — Gulf Life with Asad - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/industrial_power_distribution_and_illumination/wires-cables-industrial-building - Whole chapter: https://www.bctengineer.com/md/semester_6/industrial_power_distribution_and_illumination/chapter-3 ## Question Describe the various types of wires or cables usually used in industrial building for power and lighting system. ## Short answer For power: PVC/XLPE armoured cables (1.1kV) for feeders and motors, unarmoured for panels, flexible cables for portable equipment, and bus ducts for high currents. For lighting: PVC single-core copper wires in conduit (1-6mm²), FR/FRLS/LSZH for fire safety. Special types include fire-survival, heat-resistant, control, and instrumentation cables. Selection based on current rating, voltage drop, installation method, and fire performance. ## Answer Wires and cables are classified by **conductor**, **insulation**, **construction** and **use**. The common types in industrial buildings are: #### For power distribution 1. **PVC insulated armoured cables (1.1 kV), Cu or Al, IS 1554:** 3.5 core or 4 core cables from the main panel to sub-panels and motors, laid on trays, in trenches or buried. Steel armour gives mechanical protection. 2. **XLPE insulated armoured cables, IS 7098:** rated 90 °C, so they carry more current than PVC; used for large feeders and HV (11 kV, 33 kV) incoming cables. 3. **Unarmoured PVC/XLPE cables:** for runs inside panels, conduits and protected cable trays. 4. **Flexible cables (multi-strand, rubber or PVC sheathed):** for portable tools, cranes, hoists, welding sets and moving machines. 5. **Bus ducts / bus trunking:** for very high currents (from transformer to main panel), as an alternative to many parallel cables. #### For lighting and small power 1. **PVC insulated single-core copper wires (IS 694), 1.0–6 mm²:** run in PVC or metal conduit for lighting, fans and socket circuits. Colours: red/yellow/blue (phase), black (neutral), green (earth). 2. **FR / FRLS (fire-retardant, low-smoke) wires:** where fire safety matters. 3. **LSZH (low smoke zero halogen) cables:** for crowded or enclosed areas; give little smoke and no toxic gas in a fire. #### Special-purpose cables 1. **Fire-survival cables:** keep working during a fire; for fire alarm, emergency lighting and fire pumps. 2. **Heat-resistant cables (silicone, PTFE insulation):** near furnaces and ovens. 3. **Control cables (multi-core, small size, screened):** for control circuits, interlocks and PLC wiring. 4. **Instrumentation and data cables (twisted, screened):** for sensors and communication, to reduce noise. 5. **Bare or PVC-covered earth conductors (GI strip, copper):** for earthing. #### Selection points Current rating with derating, voltage drop, short-circuit withstand, installation method, mechanical protection, fire performance and cost. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which cable is typical for main panel to sub-panel and motor feeds, laid in trenches or buried? A. Single-core PVC wire in conduit B. Twisted screened instrumentation cable C. PVC or XLPE insulated steel armoured 3.5 core or 4 core cable D. Bare GI strip Answer: C. Armoured cables give mechanical protection for power distribution. (Key point: Armoured power cables) 2. Why are LSZH cables used in crowded or enclosed areas? A. They carry higher current than XLPE B. They survive and keep working in a fire C. They are cheapest of all wires D. They give little smoke and no toxic halogen gas in a fire Answer: D. LSZH = low smoke zero halogen, for safety in fires; fire-survival cables are the ones that keep working. (Key point: LSZH cables) 3. Which cable is suitable for portable tools, cranes and moving machines? A. Flexible multi-strand rubber or PVC sheathed cable B. Steel wire armoured XLPE cable C. Bus duct D. Control cable with GI armour Answer: A. Flexible cables tolerate movement; the others are fixed installations. 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