⚠️ Hazardous Area Classification (Zone 0, 1, 2) & DGMS Requirements

Hazardous area classification is critical in mining because methane gas (CH₄) and coal dust can ignite with a small spark.
DGMS mandates strict area classification to decide which equipment (Ex-d, Ex-ia, Ex-ib, Ex-n) can safely operate in those environments. This blog explains Zone 0, Zone 1, Zone 2, DGMS rules, EX standards, and equipment selection — in simple OME style.

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🔹 1. Why Hazardous Area Classification is Needed?

Because underground mines often contain:

• Methane gas
• Coal dust
• Fire hazards
• Electrical sparks
• Poor ventilation

Proper classification ensures: 

 ✔ Right equipment in right zone
✔ No risk of ignition
✔ Worker safety
✔ DGMS compliance

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🔹 2. Indian Standard for Hazardous Areas DGMS follows:

• IS 5572 – Classification of hazardous areas
• IS 13408 – Electrical installations in explosive atmospheres
• IS/IEC 60079 series – EX equipment

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🔹 3. Hazardous Area Classification in Mines The zones represent methane concentration & likelihood of presence.

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⭐ Zone 0 – Highest Risk Zone Definition: An area where explosive gas mixture is present continuously or for long periods. Examples:

• Sealed-off areas
• Abandoned workings
• Gob areas with methane emission
• Drainage boreholes

Equipment Allowed:

Equipment Type	Permitted
Ex-ia (Intrinsic Safety – Level a)	✔ Allowed
Ex-ib	❌ Not allowed
Ex-d	❌ Not allowed
Ex-n	❌ Not allowed
Ordinary equipment	❌ Not allowed

Zone 0 = Only Ex-ia.

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⭐ Zone 1 – Medium Risk Zone Definition: Area where explosive gas mixture is likely during normal operation. Examples:

• Development headings
• Working faces
• Return airways
• Near machinery in gassy seams

Equipment Allowed:

Equipment	Zone 1 Allowed?
Ex-d (FLP)	✔ Yes
Ex-ia	✔ Yes
Ex-ib	✔ Yes
Ex-n	❌ No
Non-FLP	❌ No

Zone 1 = Ex-d / Ex-ia / Ex-ib only.

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⭐ Zone 2 – Low Risk Zone Definition: Area where gas is not normally present, but may occur occasionally. Examples:

• Intake airways
• Haulage roads
• Travel roadways
• Pump houses

Equipment Allowed:

Equipment	Zone 2 Allowed?
Ex-n (Non-sparking)	✔ Allowed
Ex-d	✔ Allowed
Ex-ia / Ex-ib	✔ Allowed
Ordinary industrial equipment	❌ Not allowed in gassy mines
Domestic lights/switches	❌ Not allowed

Zone 2 = Ex-n permitted, but NOT domestic-grade equipment.

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🔹 4. Methane Concentration & Hazardous Areas

Zone	Methane % (Approx.)
Zone 0	>2% consistently
Zone 1	1–2% or occasional
Zone 2	<1% normally

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🔹 5. DGMS Rules for Equipment Usage in Zones 

  🔥 Ex-ia

• Allowed in Zone 0 / 1 / 2
• Highest safety level
• Used for gas detectors, sensors, cap lamps, PWS

🔥 Ex-ib

• Allowed in Zone 1 / 2
• Not safe for Zone 0

🔥 Ex-d (Flameproof)

• Allowed in Zone 1 / 2
• Used for motors, switchgear

🔥 Ex-n (Non-sparking)

• Allowed in Zone 2 only
• Not allowed in Zone 0 or 1

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🔹 6. DGMS Requirements in Hazardous Areas

1. Equipment must match zone classification
2. All electrical equipment must be approved by DGMS
3. Flamepaths inspected regularly
4. Gas testing by certified personnel
5. Methane detectors must be Ex-ia
6. Ventilation must maintain <1.25% CH₄
7. Automatic power cut-off above 1.25%

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🔹 7. Practical Examples 

  Example 1: Flameproof motor in Zone 1 

 ✔ Allowed
❌ Cannot be replaced with industrial motor Example 2: Cap lamp in Zone 0 

 ✔ Ex-ia allowed
❌ Ex-ib not allowed Example 3: LED Floodlight in Zone 2 

✔ Ex-d allowed
✔ Ex-n allowed
❌ Domestic LED not allowed

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🔥  25 MCQs (DGMS Pattern) with Answers

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1) Zone 0 means — 

a) No methane
b) Low methane
c) Continuous explosive mixture
d) Only dust
e) None
Ans: c

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2) Equipment allowed in Zone 0 —

a) Ex-d
b) Ex-ib
c) Ex-ia
d) Ex-n
e) None
Ans: c

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3) Zone 1 equipment includes —

a) Ex-n only
b) Ordinary equipment
c) Ex-d / Ex-ia / Ex-ib
d) Domestic switches
e) None
Ans: c

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4) Zone 2 allows —

a) Domestic bulbs
b) Ex-n equipment
c) No equipment
d) Only Ex-ia
e) None
Ans: b

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5) Methane above 2% equals —

a) Safe
b) Normal
c) Hazardous zone
d) Not explosive
e) None
Ans: c

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6) Ex-d is used for —

a) Cap lamps
b) Motors & switchgear
c) Tracks
d) Rails
e) None
Ans: b

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7) Intrinsically Safe equipment restricts —

a) Tyre pressure
b) Water flow
c) Energy / voltage / current
d) Heat conduction
e) None
Ans: c

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8) Zone 1 methane % approx —

a) 0%
b) >2%
c) 1–2%
d) 10%
e) None
Ans: c

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9) Gas detectors must be —

a) Ex-n
b) Ex-d
c) Ex-ia
d) IS only
e) None
Ans: c

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10) Domestic equipment is —

a) Allowed everywhere
b) Not allowed in gassy mines
c) Allowed in Zone 0
d) Allowed in Zone 1
e) None
Ans: b

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11) Zone 2 methane % —

a) >5%
b) >2%
c) <1%
d) 10%
e) None
Ans: c

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12) Ex-ib allowed in —

a) Zone 0
b) Zone 1 & 2
c) Surface only
d) None
Ans: b

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13) Flameproof equipment prevents —

a) Rain
b) Heat
c) Internal explosion propagation
d) Rust
e) None
Ans: c

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14) First step when methane >1.25% —

a) Continue work
b) Sleep
c) Cut power
d) Increase load
e) None
Ans: c

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15) Zone classification standard —

a) IS 2062
b) IS 5572
c) IS 2974
d) IS 732
e) None
Ans: b

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16) Zone 0 requires —

a) Ex-ib
b) Ex-n
c) Ex-ia only
d) Ex-d
e) None
Ans: c

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17) LED lights in Zone 2 must be —

a) Domestic type
b) Ex-n or Ex-d
c) No certification
d) Waterproof
e) None
Ans: b

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18) Methane is —

a) Non-explosive
b) Safe
c) Highly explosive
d) Heavier than air
e) None
Ans: c

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19) Zone 0 examples —

a) Workshops
b) Sealed-off areas
c) Haul roads
d) Belt roadway
e) None
Ans: b

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20) Ex stands for —

a) Export
b) Example
c) Explosion protection
d) Exhibition
e) None
Ans: c

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21) Zone 2 is —

a) Highest risk
b) Lowest risk among hazardous areas
c) No risk
d) Same as Zone 1
e) None
Ans: b

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22) Non-sparking =

a) Ex-d
b) Ex-ia
c) Ex-n
d) Ex-e
e) None
Ans: c

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23) Ex-ia acceptable faults —

a) Zero
b) Two faults
c) One fault
d) Three faults
e) None
Ans: b

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24) In Zone 1, equipment must be —

a) Ex-n
b) FLP / IS / Ex-d
c) Domestic
d) Non-electric
e) None
Ans: b

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25) Purpose of zone classification —

a) Decoration

b) Marketing
c) Choose correct EX equipment & prevent ignition
d) Improve production
e) None
Ans: c

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🔚 Conclusion

Hazardous area classification protects miners by ensuring the correct EX equipment is used in methane-rich zones.
Understanding Zone 0, Zone 1, Zone 2 is crucial for:

• Electrical supervisors
• Safety officers
• DGMS exam candidates
• Manufacturers & engineers

It ensures zero ignition and 100% compliance with DGMS rules.

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