DGMS Standards for Audio-Visual Alarms in Surface Transport Machinery & Heavy Earth Moving Machinery (HEMM)

DGMS Guidelines for Audio Visual Alarms in Surface Transport & HEMM – Safety Provisions & 25 MCQs

🧾 DETAILED NOTES

1️⃣ Introduction

Lighting systems are critical for visibility, safety, and communication in mines. DGMS mandates prior approval for all lighting equipment used in Surface coal & metal mines, Underground coal & metal mines, Oil & gas mines/fields, HEMMs, and Plants/workshops. Due to explosion hazards, methane presence, dust ignition, and visibility issues, only DGMS-approved and IS-certified lighting systems can be used.

2️⃣ Types of Lighting that Require DGMS Approval

General Illumination Lights: Fixed lighting, LED floodlights, Area lights.
HEMM On-board Lights: Headlights, Rear lights, Cabin lights, Reversing lights, Brake/indicator lamps.
Signaling & Warning Lights: Flashing beacons, Red/amber strobe lights, Stop signal lights.
Hazardous Area Lighting: Used in gassy seams and oil/gas fields. Must be certified as Flameproof (FLP) or Intrinsic Safe (IS).

3️⃣ DGMS Approval Requirements

All lighting systems must meet the following requirements:

Requirement	Description
IS/IEC Standards	IS 2206, IS 5794, IS/IEC 60079 for FLP/IS equipment
IP Rating	IP65 / IP66 for dusty/wet conditions
Vibration Testing	For HEMM and mobile equipment
Thermal Testing	To avoid surface temperature ignition

4️⃣ Approval Process and Documentation

Manufacturers must submit technical details to DGMS (Electrical Division). Sample testing (Explosion, Thermal, Impact, Photometric) is performed at recognized labs (CIMFR, CPRI). DGMS issues a Type Approval Certificate upon compliance.

5️⃣ Lighting Requirements for Underground Mines

Gassy Mines: Only Flameproof (FLP) or Intrinsic Safe (IS) equipment allowed. Voltage level must not exceed 110 V in gassy zones.
Non-Gassy Mines: IP65 rated fixtures with mechanical protection.
Cap Lamps: Must be IS-approved and regularly maintained.

6️⃣ Minimum Illumination Standards (as per DGMS)

Location	Minimum Lux Level
Underground haulage road	5 lux
Coal face	10 lux
Opencast haul road	15 lux
Workshops / plants	50 lux
Office / Control room	100 lux

⚡ QUICK ONE-LINERS

DGMS approval is mandatory for all mine lighting.
FLP/IS lights are essential in underground gassy mines.
HEMMs must have approved headlights & indicators for safe operation.
An IP65 rating is the minimum for surface mines to resist dust & water.
IEC 60079 standard specifies requirements for explosion-protected lighting.
Signaling lights must be clearly visible for effective communication.
Oil & gas fields strictly require Ex-certified lights due to explosion risk.
LED lighting is preferred for its long life, durability, and low heat emission.
All lighting fixtures must be designed to withstand severe vibration.
Testing for mine lights is conducted at recognized labs like CIMFR, CPRI, BIS.

🧠 DESCRIPTIVE MODEL Q&A

Q. Explain DGMS requirements for approval of lighting systems and indicators used in mines, including HEMMs and underground installations.

Answer:
DGMS mandates prior approval for all lighting systems and indicators used across various mining environments to ensure safety against explosion, fire, visibility hazards, and electrical faults. Key requirements include:

General Standards: All equipment must conform to relevant IS/IEC standards (e.g., IS 2206, IS 5794, IS/IEC 60079) and possess appropriate IP ratings (e.g., IP65/IP66 for dust and water protection).
Underground Gassy Mines: Lighting must strictly be Flameproof (FLP) or Intrinsically Safe (IS) to prevent ignition of flammable gases. The voltage must not exceed 110 V.
HEMMs (Heavy Earth Moving Machinery): These require specific on-board lighting including headlights, indicators, reverse warning lights, and rotating/flashing beacons, designed to be vibration-tolerant.
Testing & Certification: All lighting systems undergo rigorous testing at recognized laboratories (CIMFR, CPRI) for explosion-proof capabilities, thermal endurance, impact resistance, and photometric intensity. The final Type Approval Certificate is issued by DGMS.

🧮 25 MCQs (Dynamic Answers — 5 Options Each)

Q1. DGMS approval is required for:

Solution: Due to safety-critical nature of lighting in mines (visibility, explosion prevention), DGMS approval is mandatory for all lighting systems to ensure they meet stringent safety standards.

Q2. Underground gassy mines require:

Solution: Flameproof (FLP) or Intrinsically Safe (IS) lights are specifically designed to prevent ignition of explosive atmospheres present in gassy mines.

Q3. IP65 rating protects against:

Solution: An IP65 rating signifies that the enclosure is dust-tight and protected against water jets, making it suitable for dusty and wet mining conditions.

Q4. HEMM must have:

Solution: Headlights and indicators are crucial for safe operation and navigation of heavy earth-moving machinery.

Q5. Explosion-proof lights are tested as per:

Solution: IEC 60079 is the international standard for electrical apparatus for explosive atmospheres, including lighting.

Q6. Signaling lights are used for:

Solution: Signaling lights are a fundamental component of safety communication systems, conveying status and operational instructions.

Q7. Oil & gas fields require:

Solution: Oil & gas fields are hazardous zones requiring 'Ex-certified' (explosion-protected) lights to prevent ignition of flammable vapors.

Q8. HEMM reverse lights must be:

Solution: Reverse lights must be highly visible to warn personnel behind the vehicle in poor visibility conditions.

Q9. Lighting fixtures must withstand:

Solution: Machinery and vehicles are subjected to constant vibration, so fixtures must be tested for anti-vibration durability.

Q10. FLP stands for:

Solution: FLP is the abbreviation for "Flameproof," a protection technique used in hazardous atmospheres.

Q11. General illumination lighting used in mines are primarily:

Solution: LED lighting is preferred for general illumination due to energy efficiency, long life, and low heat.

Q12. Standardized indicator colors are usually:

Solution: Red, Amber (Warning/Moving), and Green (Safe/Operational) are standard industrial signaling colors.

Q13. Photometric testing checks:

Solution: Photometric testing measures the light output and distribution (intensity) to ensure adequate illumination.

Q14. Power supply to signal lights usually:

Solution: Control and signal circuits often use low voltages (24V or 110V) for enhanced safety.

Q15. Junction boxes underground in gassy mines must be:

Solution: Junction boxes must be Flameproof (FLP) certified to prevent an internal spark from igniting mine gas.

Q16. High mast lights are typically used at:

Solution: High mast lights provide widespread illumination over large surface areas like stockyards and open pits.

Q17. LED lighting is preferred in mines because it is:

Solution: LED technology significantly reduces power consumption and heat emission, which is beneficial for safety and cost.

Q18. Recognized DGMS testing labs for mine equipment include:

Solution: CIMFR (Central Institute of Mining and Fuel Research) is a recognized testing authority for mining equipment in India.

Q19. HEMM lighting switches should ideally be:

Solution: Ergonomic design ensures the operator can easily and quickly access and use the controls without distraction.

Q20. Flameproof light enclosures are typically made of:

Solution: Cast metal (iron or aluminum alloys) is required for strength to contain internal explosions in FLP equipment.

Q21. Oil & gas mines are generally classified as:

Solution: Due to the presence of flammable hydrocarbons, oil & gas mines/fields are inherently hazardous zones.

Q22. A critical safety aspect that lighting systems must avoid is:

Solution: Sparks from electrical equipment can instantly ignite methane gas or coal dust, leading to an explosion.

Q23. Cable glands for FLP lights must be:

Solution: The cable glands must maintain the integrity of the flameproof enclosure by preventing flame path intrusion.

Q24. Main hazard of poor lighting:

Solution: Poor visibility directly contributes to slips, trips, falls, and machinery accidents.

Q25. DGMS ensures:

Solution: The entire approval process is focused on ensuring the equipment is safe to use in the specific mine environment.

🔗 INTERNAL LINKS

Related Topic	Read More On...
Electrical Safety	Electrical Safety & Accident Investigation
HEMM Safety	Safety Features in Crawler/Tyre Mounted Machinery
Opencast Lighting	Standards of Illumination in Opencast Mines
DGMS Circulars	DGMS Training Syllabus for Electrical Engineers

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