DGMS Overman and Sirdar (coal) exam: the CMR 2017 rules and numbers you must know

Last updated 11 Oct 2026 · India (coal mines)

Short answer. The Overman and Sirdar certificate exams for coal mines are a 2-hour computer-based test of 100 marks; you pass at 50 (DGMS bye-laws, 11 Aug 2021). Most questions test the Coal Mines Regulations, 2017. Learn these first: gas limits of 0.75% in district return air and 1.25% anywhere (Reg 153), a gas test within 18 m before charging and firing (Reg 201), the sirdar's inspection within 2 hours before the shift and every 4 hours (Reg 129), and a 5-minute wait after a misfire (Reg 204).

Why learn the reason, not just the number

The CBT asks the same rule in different ways. If you know why a rule exists, you can work out the answer when the wording changes. For example, gas is tested within 18 m before firing because a shot is an ignition source and gas moves with the air. So shots are also stopped on the return side of any place where gas is found (Reg 201(1)).

రూల్ ఎందుకు ఉందో తెలిస్తే, ప్రశ్న ఎలా మార్చి అడిగినా జవాబు గుర్తొస్తుంది.

The numbers most asked

Topic	Rule	CMR 2017
Air quantity	6 m³/min per person or 2.5 m³/min per tonne per day, whichever is larger	153(2)(a)
Oxygen / CO₂	O₂ not below 19%; CO₂ not above 0.5%	153(2)(b)
Inflammable gas	0.75% in district return air; 1.25% anywhere	153(2)(c)
Temperature	Wet bulb max 33.5 °C; above 30.5 °C, air at least 1 m/s	153(2)(d)
Air measurement	Every 14 days (30 days in non-fiery / degree I seams)	156(8)
Sirdar inspection	Within 2 h before the shift, then every 4 h	129(5)
Max shots per shift	Degree II/III or fiery 40/80; other seams 50/100; opencast 60/120 (single/multi-shot exploder)	190(5)
Gas test before firing	Within 18 m, before charging and before firing	201(2)
Misfire	Wait 5 min after disconnecting; relieving hole at least 30 cm away	204(1), 204(6)
Opencast danger zone	500 m radius	196(2)(b)
Spontaneous heating	CO test every 7 days; CO/O₂ ratio every 30 days	137(12)
Stone dust	75% incombustible (85% if volatile matter over 30%); silica max 5%	144(3), 144(4)
Inundation	Within 60 m of possibly waterlogged workings, the Chief Inspector's permission is needed	150(3)
Accident notice	Written notice within 24 h; displayed 14 days	8

Common mistakes

Mixing up 0.75% and 1.25%. 0.75% applies to the general body of the district's return air; 1.25% is the ceiling anywhere in the mine.
Counting the 5 minutes from the shot. They count from disconnecting the exploder from the cable.
Thinking the Mines Act still governs. The OSH Code 2020 came into force on 21 Nov 2025 and repealed the Mines Act 1952. Section 143(3) keeps CMR 2017 in force until it is replaced, where it does not conflict with the Code.
Arriving late. No candidate is let in once the CBT has started.

Exam-day checklist

Admit card and photo ID
Reach well before the start time
Books and notes stay outside the hall
You cannot leave in the first hour
First pass: answer the sure questions; second pass: the rest

Frequently asked questions

Is the Overman/Sirdar exam still CBT in 2026?

The 2021 bye-laws make it a 2-hour CBT of 100 marks with a pass mark of 50. The last schedule we found was CBT-2025 (3 to 7 June 2025). Check dgms.gov.in for the next notice.

Is CMR 2017 still valid after the OSH Code?

Yes, for now. Section 143(3) of the OSH Code keeps regulations made under the repealed Mines Act in force, where they are not contrary to the Code, until they are superseded.

What do I need to sit the Sirdar exam?

At least 20 years of age, a valid first-aid certificate, senior secondary (or equivalent), and 3 years' coal mine experience (1 year with an approved mining diploma or degree): CMR 2017 Regs 14 and 17.

Do I need a Gas-Testing Certificate for the Overman exam?

For the unrestricted Overman exam, yes. You need an unrestricted Sirdar's Certificate and a Gas-Testing Certificate (Reg 14(5)(a)).

Is this page official?

No. It is a free, independent explainer, not affiliated with DGMS or any mining company.

Official sources

Independent study explainer. Not affiliated with or endorsed by DGMS, the Board of Mining Examinations or any mining company. Regulation summaries are simplified; check the Gazette text and current DGMS notices. Last checked 11 Oct 2026.

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