DGMS Approval Requirements for Mine Lighting Systems & HEMM On-Board Lights – Complete Notes + 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 to ensure safety against explosion, fire, and visibility hazards. For underground gassy mines, lights must be flameproof (FLP) or intrinsically safe (IS), complying with IS/IEC 60079 standards, and the voltage must not exceed 110 V. Surface and HEMM lights require IP65/66 protection and anti-vibration design. Manufacturers must submit samples for comprehensive testing (thermal, explosion, photometric) at DGMS-approved labs (CIMFR, CPRI). The final Type Approval Certificate ensures the equipment is safe, reliable, and compliant with CMR 2017 Reg. 131.

🧮 25 MCQs (Dynamic Answers — 5 Options Each)

Q1. Regulation dealing with lightning protection in mines:

Solution: Regulation 131A of CMR 2017 specifically mandates protection against lightning in surface and underground installations.

Q2. DGMS Circular for lightning protection system:

Solution: DGMS Circular 1 of 2016 provides the detailed guidelines for designing, installing, and testing LPS.

Q3. Standard followed for LPS design:

Solution: IS/IEC 62305 is the comprehensive Indian Standard for lightning protection design and risk management.

Q4. Maximum permissible earth resistance for LPS:

Solution: The earth resistance for a lightning protection system should be maintained below 10 ohms.

Q5. Frequency of LPS testing:

Solution: Earth resistance and system integrity must be tested once every six months (half-yearly), especially before the monsoon season.

Q6. Lightning conductor height above structure:

Solution: The air terminal should typically extend at least 3 meters above the highest point of the structure it is protecting.

Q7. Earth electrodes for lightning should be:

Solution: The lightning earthing pit must be kept separate from the main power system earthing to prevent surges from entering the power lines.

Q8. LPS includes:

Solution: A complete LPS consists of the air terminal (capture), down conductor (conduction), and earth electrode (dissipation).

Q9. Lightning counter used to:

Solution: A lightning counter is installed on the down conductor to record the number of lightning strikes the system has safely discharged.

Q10. DGMS Circular 3/2018 refers to:

Solution: DGMS Circular 3 of 2018 provided guidelines on the periodic measurement of earthing resistance in mines.

Q11. Lightning energy dissipated through:

Solution: The down conductor guides the lightning current safely away from the structure and into the earth pits.

Q12. Material commonly used for down conductor:

Solution: Copper or Galvanized Iron (GI) strips are used due to their high electrical conductivity and corrosion resistance.

Q13. LPS register maintained by:

Solution: The competent Electrical Engineer or Supervisor is responsible for testing and maintaining the LPS register.

Q14. DGMS mandates testing interval of:

Solution: Earth resistance and system integrity must be tested at least once every six months (half-yearly), especially before the monsoon season.

Q15. Equipotential bonding prevents:

Solution: Bonding connects all metal components to the same potential, eliminating dangerous voltage differences (shock hazards or side flashing) between structures.

Q16. LPS protects against:

Solution: LPS protects against the direct lightning strike (preventing fire) and the resulting electrical surge (protecting equipment).

Q17. Recommended earthing conductor size (minimum):

Solution: 25 mm² copper or 50 mm² GI/Steel is a common minimum requirement for LPS down conductors.

Q18. LPS resistance measured with:

Solution: A dedicated Earth Resistance Tester (often called a Megger) is the instrument used for measuring earth pit resistance.

Q19. Testing terminal provided for:

Solution: A test link is installed so the earth resistance can be measured without disconnecting the entire LPS.

Q20. LPS failures often due to:

Solution: All these factors compromise the system's low-resistance path, leading to failure.

Q21. Standard for risk assessment in LPS:

Solution: Part 2 of IS/IEC 62305 deals specifically with lightning risk management calculations.

Q22. Earth pit identification must include:

Solution: Proper records require all identifying data, including the pit number, location, and measured resistance.

Q23. LPS should be inspected before:

Solution: Testing must be completed before the monsoon season begins, as this is the period of highest lightning risk.

Q24. Surge Protection Devices (SPDs) are connected at:

Solution: SPDs must be installed at every point where a power or signal line enters the system to protect sensitive equipment.

Q25. DGMS approval 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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