TOPIC: TRUNKING SYSTEM INSTALLATION

1.0 Introduction

A trunking system is an enclosure, usually rectangular in shape, used to protect and route electrical cables. It provides a neat, safe, and flexible method of wiring, especially where many cables need to be run together.

2.0 Learning Outcomes

By the end of this lesson, the trainee should be able to:

1. Identify types of trunking and their applications.
2. Select appropriate trunking and accessories for an installation.
3. Install trunking systems according to design requirements and safety standards.
4. Perform inspection and testing on the installed trunking system.

3.0 Definition of Terms

4.0 Types of Trunking

5.0 Trunking Accessories

• Couplers – join two lengths of trunking in a straight line.
• Internal and External Bends – allow trunking to turn around corners.
• Flat Tees and Crosses – allow branching of trunking runs.
• End Caps – close off open ends.
• Reducers – connect trunking of different sizes.
• Cable Retainers / Dividers – separate power and data cables.
• Trunking Lid / Cover – closes and secures the cables inside.

6.0 Tools and Equipment

• Hacksaw / Trunking cutter
• File (for smoothing edges)
• Drill and screws
• Screwdriver set
• Measuring tape and marker
• Spirit level / chalk line
• Rawl plugs and fixing screws
• Personal protective equipment (PPE): gloves, safety goggles, helmet

7.0 Procedure for Installing Trunking System

Step 1: Planning and Marking Out

• Study the wiring diagram or layout.
• Identify routes and points of termination.
• Mark the trunking route on walls or ceilings using a chalk line.
• Ensure the route avoids obstructions and allows easy cable entry.

Step 2: Cutting and Preparing Trunking

• Measure and cut trunking to required lengths using a hacksaw.
• File edges smooth to prevent cable damage.
• Drill fixing holes (usually at 300–600 mm intervals).

Step 3: Mounting the Trunking

• Fix the trunking base securely to the wall or ceiling using screws and plugs.
• Ensure alignment with a spirit level.
• Use couplers and accessories for joints and corners.

Step 4: Laying Cables

• Ensure all burrs and sharp edges are removed.
• Lay cables neatly within the trunking.
• Use cable retainers or clips to secure cables.
• Avoid crossing or twisting cables.

Step 5: Covering and Finishing

• Fit the trunking lid securely.
• Label the trunking (e.g., “LIGHTING CIRCUIT,” “POWER CIRCUIT”).
• Clean and check for any damage or loose fittings.

Step 6: Testing and Inspection

• Check mechanical strength and alignment.
• Verify continuity, insulation resistance, and earth continuity.
• Ensure compliance with wiring regulations (e.g., KS IEC 60364).

8.0 Safety Precautions

• Always isolate power before installation.
• Use appropriate PPE.
• Avoid sharp bends that may damage cables.
• Ensure trunking is properly earthed (for metallic types).
• Keep data and power cables in separate compartments.
• Avoid overfilling trunking (max fill ~45% of cross-section).

9.0 Advantages of Trunking System

• Provides mechanical protection for cables.
• Neat and organized appearance.
• Easy to add or remove cables.
• Reduces maintenance cost.
• Enhances safety by enclosing live conductors.

10.0 Disadvantages

• More expensive than conduit systems.
• Requires careful alignment and cutting.
• Not suitable for outdoor or damp conditions (especially PVC).
• Can be bulky on walls.

11.0 Illustrations

You can include simple labeled diagrams showing:

• A trunking run along a wall
• Internal and external bends
• Trunking cross-section with cables
• Accessories like tees and couplers

12.0 Review Questions

1. Define trunking and state its main purpose.
2. Differentiate between PVC and metal trunking.
3. List five trunking accessories and their functions.
4. Explain why it is important to avoid overfilling a trunking.
5. Outline the procedure for installing a trunking system.
6. Describe three safety precautions during trunking installation.
7. State two advantages and two disadvantages of using a trunking system.