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Electrical Conduiting Overview

Electrical conduiting is a critical component of building services that provides pathways for electrical wiring, protecting cables from mechanical damage and environmental factors. This training module covers all aspects of conduit installation from planning to testing, ensuring compliance with Indian Standards and best practices.

Training Duration: 1 week

Prerequisite Skills: Basic knowledge of electrical systems, building layouts, and hand tools

1

Types of Electrical Conduits

A
Overview of Conduit Types

Conduit systems serve as pathways and protection for electrical cables. Selection depends on installation location, environmental conditions, and specific project requirements.

B
Types of Conduits & Their Applications
  • Rigid Steel Conduit (RSC): Heavy-duty conduit for exposed installations and areas requiring maximum protection (IS 1653)
  • Intermediate Metal Conduit (IMC): Similar to RSC but with thinner walls, lighter weight
  • Galvanized Iron (GI) Conduit: Corrosion-resistant steel with zinc coating, suitable for most building installations
  • PVC Conduit: Non-metallic, lightweight, suitable for concealed installations (IS 9537 Part 3)
  • HDPE Conduit: For underground installations, high impact resistance
  • Flexible Metal Conduit: For connections to motors, vibrating equipment
  • Surface PVC Trunking: For multiple cables in visible routes (IS 14927)
C
Standard Dimensions & Specifications
Conduit Type Standard Sizes (mm) Applicable IS Code Recommended Usage
PVC Conduit 20, 25, 32, 40, 50 IS 9537 Part 3 Concealed wiring in walls/slabs
GI Conduit 20, 25, 32, 40, 50 IS 1653 Exposed areas, industrial spaces
HDPE Conduit 25, 32, 40, 50, 63 IS 9537 Part 4 Underground installations
Flexible Conduit 16, 20, 25, 32 IS 3480 Connection to equipment

Selection Criteria: Always select conduit type and size based on location, environment, number of cables, future maintenance needs, and compliance with relevant IS codes.

2

Tools & Equipment

A
Essential Hand Tools
  • Measuring Tools: Measuring tape, spirit level, plumb bob
  • Cutting Tools: Hacksaw, pipe cutter, PVC cutter
  • Bending Tools: Conduit bender, bending spring
  • Threading Tools: Pipe dies, thread cutting oil
  • Marking Tools: Chalk line, pencil, marker
  • Fastening Tools: Screwdrivers, pliers, spanners
  • Drilling Tools: Electric drill with various bits
B
Specialized Equipment
  • Hydraulic Bender: For precise bending of larger conduits
  • Core Cutting Machine: For creating holes in concrete slabs/walls
  • Wire Pulling Tools: Fish tape, pull cords, cable lubricant
  • Chasing Machine: For cutting wall channels for concealed wiring
  • Testing Equipment: Continuity tester, insulation tester
C
Personal Protective Equipment (PPE)
  • Safety Helmet: For protection against falling objects
  • Safety Goggles: To protect eyes during cutting and drilling
  • Hand Gloves: For protection during handling of materials
  • Safety Shoes: With electrical insulation properties
  • Dust Mask: For protection during cutting and drilling work
  • Safety Harness: For working at heights

Tool Maintenance: Keep all tools clean, sharpened, and properly maintained. Inspect them regularly for damage and replace as needed.

3

Layout Planning & Marking

A
Understanding Electrical Layouts

Proper planning of conduit routes is essential for efficient installation, future maintenance, and compliance with IS 4648 (Guide for electrical layout in residential buildings) and IS 732 (Code of practice for electrical wiring installations).

  • Read and interpret electrical layout drawings
  • Identify locations of switches, outlets, junction boxes
  • Understand symbols and notations on electrical drawings
  • Identify circuits and their intended loads
  • Check coordination with other services (plumbing, HVAC)
B
Marking Procedure for Conduit Routes
  • Mark main distribution board (DB) location
  • Identify and mark all outlet points according to layout
  • Mark horizontal and vertical conduit routes
  • For concealed systems, mark on walls/floors before plastering
  • Ensure routes follow prescribed patterns (vertical/horizontal only)
  • Mark locations for junction boxes, pull boxes
  • Get approval from supervisor before proceeding
C
Standard Heights & Positions as per IS Codes
Item Standard Height (mm) IS Code Reference
Light Switches 1200 from FFL IS 4648
Power Socket Outlets 300 from FFL IS 4648
Distribution Boards 1500 to top from FFL IS 732
TV/Telephone Outlets 300 from FFL IS 4648
Ceiling Light Points Center of room/as per layout IS 732

Note: FFL = Finished Floor Level

Important: Always plan conduit routes to avoid water pipes (min. 300mm clearance) and maintain minimum bending radius according to IS 732 to prevent cable damage during pulling.

4

Cutting & Chasing for Concealed Conduits

A
Purpose & Requirements

For concealed wiring, chases (grooves) need to be cut in walls and floors to accommodate conduits before plastering. This must be done according to IS 732 guidelines and structural considerations.

B
Chasing Procedure
  • Mark chase lines on walls/floors as per approved layout
  • Use chasing machine or wall cutter to cut parallel lines
  • Use chisel and hammer to remove material between cuts
  • Create chase depth sufficient for conduit diameter plus 5mm
  • Ensure chase width allows conduit to fit without forcing
  • Cut outlet boxes according to marked dimensions
  • Clean chase of debris before conduit installation
  • Create rounded corners at bends for smooth conduit installation
C
Structural Considerations & Limitations
  • Never chase through load-bearing elements without structural approval
  • Horizontal chases should not exceed 1/3 wall thickness
  • Vertical chases should not exceed 1/4 wall thickness
  • Avoid chasing near corners (min. 200mm distance)
  • Do not make diagonal chases (only vertical or horizontal)
  • Maintain minimum 300mm distance from other service lines
  • For RCC structures, coordinate chasing with structural engineer
D
Conduit Cutting & Preparation
  • Measure required conduit length accurately
  • Cut conduit using appropriate tool (hacksaw for metal, PVC cutter for PVC)
  • Remove burrs from cuts using reamer or file
  • For metal conduits, apply anti-corrosion coating at cut ends
  • Thread metal conduits if required for connections
  • Use thread-cutting oil for smoother threading

Safety First: Always wear appropriate PPE (goggles, dust mask, gloves) during chasing and cutting operations. Check for existing electrical wires or plumbing before chasing.

5

Conduit Bending Techniques

A
Purpose & Importance

Proper conduit bending ensures smooth cable pulling, maintains cable capacity, and creates professional installations while following IS 732 guidelines for minimum bending radius.

B
Types of Bends & Calculations
  • 90° Bend: Standard right-angle turn
  • Offset Bend: Two opposing bends to navigate obstacles
  • Saddle Bend: Three bends to go over obstacles
  • Three-Point Bend: For creating U-shaped bends
  • Custom Angle Bends: For specific route requirements

Conduit bending requires calculation of setbacks and understanding of "gain" or "shrinkage" to achieve accurate results.

C
Bending Procedures for Different Materials
  • Metal Conduit Bending:
    • Mark bend point on conduit with allowance for setback
    • Insert conduit into bender, aligning mark with appropriate arrow
    • Apply steady pressure to bend to desired angle
    • Use degree marks on bender for accurate angles
    • Check bend against drawing or template for accuracy
  • PVC Conduit Bending:
    • Use bending spring (internal or external type)
    • Heat PVC conduit evenly using hot air gun
    • Bend gradually to desired angle when pliable
    • Hold in position until cool and set
    • Remove bending spring carefully
D
Minimum Bending Radius Requirements
Conduit Size (mm) Min. Bending Radius (Metal) Min. Bending Radius (PVC) IS Code Reference
20 120mm (6 × dia) 100mm (5 × dia) IS 732
25 150mm (6 × dia) 125mm (5 × dia) IS 732
32 192mm (6 × dia) 160mm (5 × dia) IS 732
40 240mm (6 × dia) 200mm (5 × dia) IS 732

Pro Tip: When multiple bends are required in a single run, the total angle of all bends should not exceed 360° between pull points. The maximum number of 90° bends should be limited to four between pull points to facilitate cable pulling.

6

Conduit Installation & Fixing Methods

A
Conduit Accessories & Fittings
  • Couplers: For joining straight conduit sections
  • Elbows: Factory-made bends (45°, 90° etc.)
  • Junction Boxes: For cable branching points (IS 3419)
  • Inspection Bends: For access to cable runs
  • Saddles: For surface mounting of conduits
  • Clips: For securing conduits
  • Lock Nuts & Bushes: For terminating conduits
  • End Caps: For temporarily sealing open ends
B
Installation Procedure for Concealed Conduits
  • Prepare chases as per earlier section
  • Cut conduits to required lengths, including bends
  • Join conduit sections using appropriate fittings
  • For PVC conduits, use solvent cement at joints
  • For metal conduits, ensure threaded connections are tight
  • Install outlet boxes and junction boxes
  • Secure conduits in chase using cement mortar patches
  • Ensure all joints are watertight
  • Install draw wire (nylon or GI wire) for later cable pulling
  • Temporarily seal all conduit ends to prevent debris entry
C
Installation Procedure for Surface Conduits
  • Mark conduit route on surface according to drawing
  • Mark positions for saddles/clips (spacing as per IS 732)
  • Drill holes for fixing saddles/clips
  • Fix saddles/clips using appropriate fasteners
  • Prepare conduit sections with necessary bends
  • Install conduits in saddles/clips ensuring correct alignment
  • Join conduit sections using appropriate fittings
  • Mount junction boxes and outlet boxes
  • Install draw wire for later cable pulling
D
Fixing Intervals & Support Requirements
Conduit Size (mm) Max. Distance Between Supports (m) IS Code Reference
20 0.75 IS 732
25 0.75 IS 732
32 1.00 IS 732
40 and above 1.00 IS 732

Additional Requirements: Supports should be placed within 300mm of any junction box, bend, or termination.

Important Note: For concealed conduits in RCC slabs, conduits must be firmly secured before concrete pouring to prevent floating. Maximum conduit outer diameter should not exceed 1/3 of the slab thickness as per IS 732.

7

Junction Boxes & Outlet Boxes

A
Types & Purpose

Junction boxes and outlet boxes provide access points for cable connections, branching, and terminations. They are essential for maintenance and comply with IS 732 requirements.

  • Junction Boxes: For cable joining and branching points
  • Switch Boxes: For mounting switches and controls
  • Socket Outlet Boxes: For mounting power outlets
  • Ceiling Rose Boxes: For light fixture connections
  • Fan Boxes: Reinforced boxes for ceiling fan mounting
  • Pull Boxes: For long conduit runs to facilitate cable pulling
B
Standard Dimensions & Selection
Box Type Standard Dimensions (mm) Material Options Usage
Single Switch Box 75 × 75 × 50 GI, PVC Single or double switches
Multiple Switch Box 200 × 75 × 50 GI, PVC Multiple switches (6-8)
Junction Box 100 × 100 × 50 GI, PVC Cable connections, branching
Fan Box 140 × 140 × 65 GI Ceiling fan mounting
C
Installation Procedure
  • For Concealed Installations:
    • Cut appropriately sized opening in wall/ceiling
    • Connect conduits to box using appropriate fittings
    • Ensure proper alignment with finished surface
    • Secure box firmly in position
    • Seal around box with plaster
  • For Surface Installations:
    • Mark position as per drawing
    • Drill holes for mounting screws
    • Connect conduits to box knockouts using appropriate fittings
    • Secure box to surface
    • Ensure proper alignment
D
Critical Requirements & Precautions
  • All metallic boxes must be properly earthed as per IS 3043
  • Maintain minimum 300mm separation from water pipes
  • Junction boxes must remain accessible after installation
  • Box size must accommodate the number of cables/connections
  • Install protective caps on unused knockouts
  • Ensure boxes are flush with finished surface (±2mm tolerance)
  • For outdoor installations, use weatherproof boxes with proper IP rating

Cable Space Requirement: According to IS 732, the space within boxes should be sufficient to accommodate cables without bending them to a radius less than that specified for the cable type being used. This typically requires box depth to be at least 1.5 times the cable diameter.

8

Cable Pulling Techniques

A
Cable Pulling Preparation

Proper preparation ensures successful cable pulling without damage to cables or conduits, in compliance with IS 732.

  • Inspect entire conduit run for obstructions
  • Verify conduit size is appropriate for cable quantity and size
  • Calculate maximum fill percentage (40% for multiple cables as per IS 732)
  • Ensure draw wire is in place throughout the conduit
  • Prepare cable drum for smooth unwinding
  • Calculate pulling force requirements
  • Prepare lubricant for complex pulls
B
Conduit Fill Calculations

IS 732 specifies maximum conduit fill percentages to ensure cables are not damaged during installation and can dissipate heat during operation.

Number of Cables Maximum Fill % IS Code Reference
1 Cable 53% IS 732
2 Cables 31% IS 732
3 or more cables 40% IS 732

Formula: Fill % = (Sum of cable cross-sectional areas / Conduit internal cross-sectional area) × 100

C
Cable Pulling Procedure
  • Attach cables to draw wire using pulling grip or tape
  • For multiple cables, stagger the connection points
  • Apply cable lubricant at entry point for easier pulling
  • Pull steadily with constant force (avoid jerking)
  • Have assistant feed cable to avoid kinking
  • For long runs, use intermediate pulling points
  • Leave sufficient slack at each end (min. 300mm)
  • Label cables immediately after pulling
D
Troubleshooting Common Issues
  • Cable Jamming: Back out cables, use more lubricant, try again with less force
  • Draw Wire Breaking: Insert new draw wire from nearest junction box
  • Excessive Resistance: Verify conduit is not crushed or obstructed
  • Damaged Cable Insulation: Inspect conduit for sharp edges or burrs
  • Cable Too Short: Never splice inside conduit; replace with longer cable

Maximum Pull Force: Never exceed the maximum pulling tension specified for the cable. As a general rule, for PVC insulated cables, limit pulling force to 30N per mm² of conductor cross-section. Excessive force can damage cable insulation and affect performance.

9

Earthing & Bonding for Conduit Systems

A
Purpose & IS Code Requirements

Proper earthing of metallic conduit systems is essential for safety, ensuring that fault currents have a low-resistance path to ground. This is governed by IS 3043 (Code of practice for earthing) and IS 732.

B
Earthing Methods for Metal Conduits
  • Continuous Earth: Ensure electrical continuity throughout the system
  • At Distribution Boards: Connect conduit to earth terminal
  • At Junction Boxes: Use earth continuity connectors
  • At Outlets: Connect metal boxes to earth terminal
C
Continuity Testing & Installation Process
  • Connect earth continuity conductor (min. 2.5mm² copper) to each metal box
  • Ensure proper earth bonding at all metallic joints
  • Use earth clamps or lugs for secure connections
  • For threaded connections, ensure metal-to-metal contact
  • Connect main earthing terminal to building earth electrode
  • Test earth continuity with continuity tester
  • Measure earth resistance (should be less than 1 ohm within system)
  • Document all earth resistance readings
D
Special Requirements for Different Environments
Environment Special Requirement IS Code Reference
Wet Areas Additional local earth bonding IS 3043
Hazardous Locations Explosion-proof fittings & redundant earth IS 5571
IT Equipment Areas Clean earth (separate from power earth) IS 3043
Lightning Protection Zones Bonding to lightning protection system IS 2309

Critical Safety Requirement: Earth fault loop impedance must be low enough to ensure operation of protective devices within required time (0.4 seconds for socket circuits, 5 seconds for fixed equipment as per IS 732). This should be verified by testing.

10

Testing & Commissioning

A
Pre-Commissioning Checks
  • Visual inspection of entire conduit system
  • Verify all boxes are accessible and properly covered
  • Check mechanical fixing of all components
  • Verify conduit routes match approved drawings
  • Ensure all cables are properly identified
  • Check adequate space at termination points
  • Inspect for any physical damage to conduits or cables
B
Testing Procedures & Standards
  • Continuity Testing: Test conductors and protective conductors for continuity
  • Insulation Resistance Test: Using 500V insulation tester (min. 1 MΩ)
  • Earth Fault Loop Impedance Test: To verify protection operation
  • Polarity Test: Ensure correct connection of switches and sockets
  • RCD Operation Test: Where applicable
  • Functional Test: Verify correct operation of all circuits
C
Documentation Requirements
  • As-built conduit layout drawings
  • Circuit diagrams with cable sizes and types
  • Test certificates for all required tests
  • Material test certificates
  • Earthing system test results
  • Photographic evidence at critical stages
  • Inspection checklists signed by qualified personnel
  • Handover certificate
D
Common Defects & Remedial Actions
Defect Potential Cause Remedial Action
Poor Continuity Loose connections Tighten all connections
Low Insulation Resistance Damaged cable insulation Identify damage point, replace cable
High Earth Loop Impedance Poor earth connections Improve earth bonding, add additional earth paths
Cable Identification Issues Missing/incorrect labels Re-identify all cables according to drawing

Acceptance Criteria: Final installation must comply with IS 732 and any project-specific requirements. All test results must be within acceptable limits as defined in the standards. Documentation must be complete and accurate to enable future maintenance.

11

On-Job Training Quality & Best Practices

A
Importance of On-Job Training (OJT)

On-Job Training (OJT) is crucial for developing practical skills in electrical conduiting. It bridges the gap between theoretical knowledge and real-world application, ensuring that trainees can perform tasks efficiently, safely, and to high quality standards.

  • Develops practical skills and hands-on experience.
  • Enhances understanding of site-specific challenges.
  • Improves problem-solving abilities in real-time scenarios.
  • Reinforces safety protocols and best practices.
  • Fosters teamwork and communication skills.
B
Key Elements of Quality OJT
  • Qualified Trainers: Experienced supervisors or senior electricians who can effectively demonstrate and mentor.
  • Structured Curriculum: A clear plan outlining learning objectives, tasks, and assessment criteria.
  • Hands-on Practice: Ample opportunities for trainees to perform tasks under supervision.
  • Regular Feedback: Constructive feedback on performance, identifying areas for improvement.
  • Safety Integration: Consistent emphasis on safety procedures and PPE usage throughout training.
  • Problem-Solving Scenarios: Presenting real-world issues to encourage critical thinking and decision-making.
  • Tool Proficiency: Training on proper handling, maintenance, and safe use of all relevant tools and equipment.
  • IS Code Application: Practical application of relevant Indian Standards in daily tasks.
C
Assessment & Continuous Improvement
  • Performance Checklists: Use checklists to evaluate practical skills and adherence to procedures.
  • Skill Demonstrations: Require trainees to demonstrate proficiency in key conduiting tasks.
  • Knowledge Quizzes: Short quizzes to assess understanding of theoretical concepts and IS codes.
  • Incident Review: Analyze any near-misses or incidents to learn and improve safety practices.
  • Trainee Feedback: Collect feedback from trainees to improve the OJT program.
  • Mentor Evaluation: Regularly evaluate trainers' effectiveness and provide them with professional development.

Effective OJT: A well-structured OJT program, combined with continuous assessment and feedback, is vital for producing highly skilled and safety-conscious electrical professionals. It ensures that quality is built into every step of the conduiting process.

12

Important IS Codes for Electrical Conduiting

A
Key Indian Standards for Reference
IS Code Title Relevance to Conduiting
IS 732 Code of practice for electrical wiring installations Overall requirements for electrical installations
IS 9537 Conduits for electrical installations Specifications for different types of conduits
IS 1653 Rigid steel conduits for electrical wiring Specifications for metal conduits
IS 3419 Fittings for rigid non-metallic conduits Specifications for PVC conduit fittings
IS 2667 Fittings for rigid steel conduits for electrical wiring Specifications for metal conduit fittings
IS 3043 Code of practice for earthing Earthing requirements for electrical systems
IS 4648 Guide for electrical layout in residential buildings Layout planning for residential electrical installations
IS 14927 Cable trunking and ducting systems for electrical installations Specifications for surface trunking systems
IS 5571 Guide for selection of electrical equipment for hazardous areas Special requirements for hazardous locations
IS 8623 Specification for low-voltage switchgear and controlgear assemblies Requirements for distribution boards

Important: Always refer to the latest edition of these standards. IS codes are periodically revised to incorporate technological developments and improved safety practices. The Bureau of Indian Standards (BIS) website or licensed copies should be consulted for the most up-to-date information.

13

Conclusion

Electrical conduiting is a critical element of any building's electrical infrastructure. A properly installed conduit system provides protection for wiring, facilitates future maintenance, and ensures safety and compliance with relevant codes and standards.

By following the procedures outlined in this training module and adhering to the requirements of the Indian Standards, electricians and construction professionals can ensure high-quality installations that will function reliably throughout the building's lifecycle.

Remember that proper planning, quality materials, skilled workmanship, and thorough testing are the cornerstones of excellent conduiting work. Always prioritize safety and compliance with standards in all electrical installations.

Key Takeaway: Quality electrical conduiting ensures safety, durability, and ease of maintenance for the entire electrical system.

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