CISF Constable is responsible for providing security and fire protection services to critical infrastructure, including 65+ international and domestic airports (including Delhi, Mumbai, and Bengaluru), nuclear installations (like BARC and NPCIL plants), space establishments (ISRO), defence PSUs, government buildings, heritage monuments (including the Taj Mahal and Red Fort), metro rail networks, and seaports. CISF is unique among CAPFs as it primarily guards civilian infrastructure. Constable (Fire) posts are specifically for fire prevention and firefighting duties at industrial units and airports.

Male CISF Constable candidates must have a minimum height of 165 cm (157.5 cm for scheduled tribes), with chest measurement of 81 cm unexpanded and minimum 86 cm expanded (5 cm expansion). Female candidates need 157 cm minimum height (154 cm for ST). The Physical Efficiency Test includes 1.6 km run in 8 minutes (male) — note this is different from other CAPFs — and 800 metres in 4 minutes (female). For Constable Fire posts, additional fire-related physical tests are conducted. Eye standards are strict — no colour blindness for Fire posts.

CISF Constable Fire posts involve firefighting and fire prevention duties at airports, industrial units, and nuclear installations. These personnel are trained firefighters who handle fire emergencies, conduct fire safety inspections, and operate fire tenders. Tradesmen posts cover skilled trade roles like Driver, Cook, Safai Karamchari (Housekeeping), Tailor, Cobbler, Gardener, and Barber that support CISF unit operations. While both are at the same pay level (Level 3, Rs. 21,700), Fire posts carry operational risk allowances and special firefighting pay.

CISF Constable starts at Level 3 (Rs. 21,700) and can be promoted to Head Constable (Level 4), ASI (Level 5, Rs. 29,200), SI (Level 6), and Inspector (Level 7) through departmental promotion exams. CISF offers unique opportunities to work at international airports in major cities, providing exposure to aviation security protocols. Constables working at airports receive additional aviation security allowances. CISF personnel are also deployed for VIP protection at sensitive government buildings.

CISF is primarily a security and fire protection force for industrial and critical infrastructure, unlike CRPF (internal security/anti-insurgency), BSF (border guarding), and ITBP/SSB (mountain/border forces). CISF personnel work in a more urban, professional environment — guarding airports, metro stations, and nuclear plants — rather than border outposts or counter-insurgency zones. CISF is also the largest industrial security force globally with 1.5+ lakh personnel. The work environment is generally less physically demanding but requires high alertness and professional security skills.