Introduction
In Module 3 of the ITI Electrician syllabus, trainees will learn about the various types of wires used in electrical installations, standard jointing techniques, proper soldering methods, and the fundamentals of underground (U.G.) cable laying. This knowledge is essential for ensuring strong electrical connections and safe wiring systems in both domestic and industrial settings.
📘 What You Will Learn
- Types of electrical wires and conductors
- Common wire joint methods and their applications
- Tools and techniques for effective soldering
- Cable insulation, protection, and underground installation practices
- Safety precautions during soldering and cable laying
🧵 Types of Electrical Wires
- Single-Core Wires – Common for internal wiring
- Twin Core Wires – For appliances and domestic supply
- Multi-Stranded Wires – Flexible, used in panel boards
- Armoured Cables – Heavy-duty cables for outdoor and underground use
Conductor Materials:
- Copper (good conductivity)
- Aluminium (lighter, cost-effective)
🔗 Electrical Joints and Connections
Good electrical joints are crucial for continuity and minimal power loss.
🔹 Types of Wire Joints
- Twist Joint – Basic joint for connecting two wires
- Western Union Joint – Strong mechanical and electrical joint
- Rat-Tail Joint – Simple joint for connecting stranded wires
- Britannia Joint – Used for cable jointing with high mechanical strength
🔧 Soldering – Process and Tools
🔹 Purpose of Soldering
- Improves conductivity
- Provides mechanical bonding
- Prevents corrosion at joints
🔹 Soldering Tools
- Soldering iron
- Solder wire (60/40 tin-lead)
- Flux (Zinc Chloride or Rosin)
- Wire stripper and cutter
🔹 Steps of Soldering
- Clean the wires
- Apply flux to joint
- Heat the soldering iron
- Apply solder and ensure it flows
- Let it cool naturally
⚠️ Always follow safety precautions during soldering: use safety glasses and avoid inhaling fumes.
⚡ Underground (U.G.) Cables – Basics
🔹 What are U.G. Cables?
Cables laid below the surface for safe and secure electrical transmission.
🔹 Types of Underground Cables
- LT Cables (Low Tension)
- HT Cables (High Tension)
- XLPE Cables (Cross-linked Polyethylene)
🔹 Cable Installation Steps
- Trenching
- Laying sand and protective bricks
- Placing the cable
- Backfilling and route marking
🔹 Cable Jointing
- Straight-through joint
- Tee joint
- Heat-shrinkable sleeves or resin kits used
📎 Summary Table
| Topic | Key Component | Remarks |
|---|---|---|
| Wire Types | Single-core, Twin-core, Multi-strand | Chosen based on application |
| Joint Types | Rat-Tail, Western Union, Britannia | Strength varies by type |
| Soldering | Solder, Flux, Iron | Clean surface essential |
| U.G. Cables | XLPE, Armoured | Used for underground transmission |
