NEC T&T Wiring Code & Drawings

Introduction to T&T Wiring Code and General Rules

Objectives and Legal Framework

  • Trinidad and Tobago Electrical Wiring Code governs electrical installations.
    • Laws include:
    1. Electricity Commission Act (Chapter 54:70)
    2. Electric Installations (Buildings) Act (Chapter 54:71)
    3. Electricity (Inspection) Act (Chapter 54:72)
  • Wiring Standards and Regulations:
    • Part 1: Low Voltage Installations (TTS 171: PART 1: 2015)
      • Aligns with:
      • National Fire Protection Association (NFPA 70) National Electric Code (NEC 2011)
      • British Standards Institution (BS 7617:2008)
    • Part 2: High Voltage Installations (TTS 171: PART 2: 2002)
    • T&TEC Wiring for Lighting and Power (8th Edition, 2005)

Key Definitions and Roles

  • Permit: Written permission from the inspection department to start work on electrical installations.
  • Current Permit: Allows the supply authority to provide electricity to a specific installation.
  • Approved: Acceptable by the enforcing authority.
  • Accessible: Wiring or equipment can be exposed without damage to the building.
  • Electrical Inspectorate: Department responsible for the inspection and certification of electrical work.
  • Supply Authority: Trinidad and Tobago Electricity Commission (T&TEC).

Conductor Materials and Sizing

Understanding Conductors

  • Rationale: Essential for determining the appropriate conductors for installations.
  • Objectives include:
    1. Define terms relevant to conductor specifications.
    2. Apply rules for conductor sizing based on load and installation conditions.

Essential Definitions

  • Ampacity: Maximum continuous current a conductor can carry without exceeding its temperature rating.
  • Neutral Conductor: Grounded conductor in a 3-phase or 2-wire system.
  • Conductor Types:
    • Stranded Conductor: More flexible, made from multiple small wires.
    • Single Solid Wire: Stiffer, singular wire type.

Conductor Regulations

  • Minimum Size Requirements:
    • Depends on conductor type and usage conditions.
    • Observing termination temperatures is crucial.
  • Identification:
    • Colour coding helps identify functions:
      • Line 1 - Brown
      • Line 2 - Black
      • Neutral - Grey
      • Ground - Green/Yellow Stripes

Special Considerations for Cable Installation

  • Ensure cables are adequately protected against mechanical damage and environmental factors.
  • Follow regulations for installation in different environmental conditions (damp, corrosive, etc).

Service and Grounding Requirements

Importance of Proper Service Installation

  • Essential for safe and reliable electrical service in dwellings.

Key Terms for Residential Service

  1. Service Line: Electric line supplying energy to consumers.
  2. Point of Supply: Where the energy is supplied to the installation.
  3. Disconnecting Means: Devices to disconnect electrical circuits from their source.
  4. Overcurrent Protective Device (OCPD): Protects circuits from overload.
  5. Panelboard: Main distribution board with circuit protection.

Installation Procedures

  • Proper identification of service equipment and adherence to regulatory standards is crucial.
  • Both overhead and underground service installations have specific codes.

Lighting Equipment and Requirements

Types of Lighting Sources

  • Incandescent: Traditional light; less efficient, high heat.
  • Fluorescent: More efficient, uses less energy.
  • High-Intensity Discharge (HID): Used for street and security lighting.
  • Light Emitting Diode (LED): Most efficient, long lifespan.

Key Terms in Lighting

  • Luminaire: Fixture containing the light source.
  • Ballast: Component to regulate current in fluorescent and HID lamps.
  • Wattage Marking: Maximum allowable wattage should be indicated on fixtures.
  • Thermal Protection: Required for some types of luminaires.

Electrical Drawings and Symbols

Understanding Types of Drawings in Construction

  • Orthographic Projections: Used to show views on two-dimensional planes (top, front, side).
  • Electrical Symbols: Must be recognized to interpret electrical drawings efficiently.
  • Block Diagrams: Simplified representations of electrical systems showing components and connections.
  • Wiring Diagrams: Detailed layouts showing the physical arrangement of circuits and components, essential for installation and troubleshooting.

Summary

  • Mastering T&T wiring code, conductor specifications, service requirements, lighting types, and electrical diagrams and symbols is essential for a successful career in electrical installations.