Code of Practice for Fire Safety in Cable Runs

IS 12459: Scope - Key Points & Specifications

Scope Overview:

• IS 12459 covers standards related to automatic fixed fire extinguishing installations.
• It specifies definitions, test methods, and performance criteria for fire extinguishing systems.
• The standard ensures compliance via rounded-off values per IS 2-1960 (Clause 0.5).

Key Specifications:

• Extinguishing Media (Clause 6.2):

  • Carbon dioxide (IS 6382-1984)
  • High expansion foam
  • Other media as per operational requirements

• Ventilation (Clause 7.6):

  • Forced ventilation systems must be capable of exhausting smoke generated by fire.

Rounding Off Values (Clause 0.5):

• Final test or analysis results must be rounded off according to IS 2-1960.
• The number of significant digits in the rounded value should match the specified value.

Summary Table: Extinguishing Media Types

If you need detailed formulas or design methods, please specify the particular fire extinguishing system or component.

IS 12459: Key Definitions & Specifications Summary

Clause 2.1 - Definitions:

• This clause establishes the terminology used in the standard to ensure clarity and uniform understanding.

Clause 0.5 - Rounding Off:

• Final values from tests or calculations must be rounded per IS 2:1960.
• Retain the same number of significant digits as the specified value.

Clause 7.6 - Forced Ventilation:

• If forced ventilation is provided, it must be capable of exhausting smoke generated by fire.

Clause 6.2 - Extinguishing Media:

• Automatic fixed fire extinguishing systems may use:
  • Carbon dioxide (per IS 6382:1984)
  • High expansion foam
  • Other media as per operational requirements

Important Notes:

Rounding Off per IS 2:1960 (Simplified):

This concise overview helps ensure compliance with IS 12459 definitions and related specifications.

IS 12459: Basic Fire Protection for Cable Trenches/Tunnels

Key Considerations (Clause 3.1)

• Delay fire damage to cables to maintain function.
• Prevent/retard flame spread along cable runs.
• Compartmentalize cable runs to localize fire.
• Install fire detection & alarm systems.
• Provide automatic fixed fire extinguishing systems.

Fire Extinguishing Systems (Clause 6.1 & 6.2)

• Automatic fixed extinguishing recommended for long cable runs (heavy industries, power stations).
• Extinguishing media options:
  • Carbon dioxide (IS: 6382-1984)
  • High expansion foam

Ventilation (Clause 7.6)

• Forced ventilation must exhaust smoke effectively during fire.

Summary Table of Fire Protection Elements

Fire Protection Concept Diagram

flowchart TD
    A[Fire Protection Concept] --> B[Delay Fire Damage]
    A --> C[Prevent Flame Spread]
    A --> D[Compartmentalize Runs]
    A --> E[Fire Detection & Alarm]
    A --> F[Automatic Extinguishing]
    A --> G[Smoke Exhaust Ventilation]

Note: For detailed design, refer to relevant IS codes for detectors, extinguishing media, and fire resistance tests.

IS 12459: Compartmentation Key Points

1. Critical Areas for Cable Protection (Clause 3.2.2)

• 1 m length on either side of:
  • End terminations or joints
  • Crossings or T-joints
• Entire length of cable in:
  • High temperature or highly vulnerable areas
  • Exposed vertical runs

2. Compartmentation Requirements (Clauses 4.1 & 5.2)

• Cable tunnels/galleries must be subdivided by fire-resistant walls at intervals ≤ 30 m.
• Openings must be sealed with fire stops matching the fire rating of the building component.
• Fire stop and barrier wall ratings per:
  • IS 12458-1988 (fire stop test)
  • IS 3809-1979 (barrier wall test)
• Fire check doors with the same fire rating must be installed in barrier walls.

3. Installation Zones (Clause 5.2)

• Each compartment is a separate zone for detector installation (refer IS 2189-1988).

4. Emergency Lighting (Clause 7.1)

• Self-contained emergency lighting is mandatory in:
  • Sub-stations
  • Cable basements and tunnels
  • Tall escape routes and exits lacking cable ventilation

Summary Table: Compartmentation Spacing & Fire Rating

flowchart LR
    A[Cable Tunnel/Gallery] -->|Divide every ≤30 m| B[Fire Resistant Wall]
    B --> C[Fire Stop Sealing]
    C --> D[Fire Check Doors]
    D --> E[Separate Detection Zone]

This ensures fire spread prevention and localized detection within cable compartments.

IS 12459: Fire Detection and Alarm Systems - Key Points

1. Types of Detectors (Clause 5.1)

• Smoke detectors: IS 11360-1985
• Heat detectors (point type): IS 2175-1988
• Linear heat detectors: Suitable for long cable runs or bunches (Clause 5.2.1)

2. Cable Protection (Clause 4.3 & 5.1)

• Entire cable runs must be protected by automatic fire alarm systems.
• Physical barriers ≥ 1 m length at intervals ≤ 30 m.
• Barriers at cable direction changes and crossings.
• Barrier fire resistance = building construction fire resistance.

3. Automatic Fixed Fire Extinguishing (Clause 6.1)

• Required for long cable runs in heavy industries, power stations, etc., supplementing detection.

Summary Table:

flowchart LR
    A[Fire Detection System] --> B[Smoke Detectors (IS 11360)]
    A --> C[Heat Detectors (IS 2175)]
    A --> D[Linear Heat Detectors]
    B & C & D --> E[Cable Protection]
    E --> F[Physical Barriers (≥1m, ≤30m spacing)]
    E --> G[Barrier Fire Resistance = Building]
    A --> H[Automatic Fixed Fire Extinguishing (Heavy Industry)]

This ensures comprehensive fire safety for cable runs per IS 12459.

IS 12459: Fire Extinguishing System - Key Points

1. Extinguishing Media (Clause 6.2)

• Automatic fixed fire extinguishing systems may use:
  • Carbon Dioxide (CO₂) — Refer IS:6382-1984 for design & installation.
  • High Expansion Foam

2. Application (Clause 6.1)

• Automatic fixed fire extinguishing systems are mandatory for:
  • Long cable runs in heavy industries
  • Electricity generating stations
  • Areas with high fire risk

3. Detectors (Clause 5.2.1)

• Linear detectors can be used:
  • For individual cables
  • For cable bunches

4. Emergency Lighting (Clause 7.1)

• Self-contained emergency lighting units must be installed in:
  • Sub-stations
  • Cable basements/tunnels
  • Tall escape routes and exits without cable ventilation

Typical Design Considerations (from IS 6382 & general practice):

Simplified Flow Diagram for Fire Extinguishing System:

flowchart LR
    A[Fire Detection] --> B[Alarm Activation]
    B --> C[Automatic Extinguishing System]
    C --> D{Extinguishing Media}
    D --> E[CO₂ System]
    D --> F[High Expansion Foam]
    E --> G[Discharge Nozzles]
    F --> G
    G --> H[Fire Suppression]

For detailed design, installation, and maintenance, refer to:

• IS:6382-1984 (CO₂ systems)
• IS 12459 Clause 6 and 7
• Relevant fire detector specifications (smoke/heat detectors)

Note: Always ensure compliance with local fire safety regulations and standards.

IS 12459 - Clause 7.6: Miscellaneous - Key Specification

• Forced Ventilation for Smoke Exhaustion:
  Where forced ventilation is provided, it must be capable of exhausting smoke generated by fire effectively.

Related Key Points from IS 12459:

• Fire Extinguishing Media (Clause 6.2):
  Automatic fixed fire extinguishing systems may use:

  • Carbon dioxide (IS: 6382-1984)
  • High expansion foam

• Rounding Off Values (Clause 0.5):
  Results of tests or calculations should be rounded off as per IS 2-1960, retaining the same number of significant digits as the specified values.

Summary Table for Forced Ventilation (Conceptual)

flowchart TD
    A[Fire Occurs] --> B[Smoke Generation]
    B --> C[Forced Ventilation System]
    C --> D[Smoke Exhausted Outside]
    D --> E[Safe Environment Maintained]

Note: For detailed design and capacity calculations, refer to IS 12459 full text and related ventilation/fire safety standards.

IS 12459: References and Related Standards - Key Points

• Rounding off values: As per Clause 0.5, all test or analysis results must be rounded according to IS 2:1960. The number of significant digits in the rounded value should match the specified value.

• Fire resistant cables: Currently covered under a separate standard. When that IS is formulated, IS 12459 will reference it and delete Clause 2.1 note.

• Ventilation: Clause 7.6 mandates forced ventilation systems must be capable of exhausting smoke generated by fire.

Important Related Standard:

Summary Table: Rounding off as per IS 2:1960

For detailed design or testing, always consult the latest editions of referenced IS codes and related standards.