Wiring & Installation MCQ
House wiring, conduit, cable tray, DB wiring — practical installation ke sawaal jo site pe kaam aate hain. 5 parts mein divide.
House Wiring Kya Hai?
Main Mohammad Arif – 12+ saal Gulf aur India ke electrical supervisor. Wiring installation ka basic se advanced tak ka knowledge hona chahiye – residential ho ya commercial, har site pe wiring ka kaam hota hai. Gulf mein civil defence aur utility standards (DEWA, KAHRAMAA) ke hisaab se wiring karni padti hai.
Wiring installation mein cable selection, conduit routing, DB (Distribution Board) design, earthing, aur bonding sab important hain. Safety, longevity, aur future maintenance ke liye standard practices follow karni chahiye.
Wiring Ke Types (Common)
| Type | Description | Use Case |
|---|---|---|
| Concealed Wiring | Walls/ceiling me chhupi hui (conduit ke andar) | Residential, permanent buildings |
| Surface Wiring (Casing-Capping) | Wall pe surface mount, conduit/trunking | Renovation, temporary sites |
| Cable Tray Wiring | Open tray mein cables laid | Industrial, commercial buildings |
| Underground Cable | Direct buried ya conduit mein | External distribution |
Conduit Aur Cable Management
Conduit Types
- PVC Conduit – Non-conductive, lightweight, corrosion resistant, common for concealed wiring.
- GI (Galvanized Iron) Conduit – Mechanical strength, fire resistant, industrial/surface use.
- Flexible Conduit – For motor/vibrating equipment connections.
Cable Tray & Trunking
- Cable Tray – Organised routing for large number of cables, good ventilation.
- Trunking – Enclosed channel, surface mounted, easy access.
- Segregation – Power and control cables separate to avoid EMI.
Cable Sizing – Load Aur Voltage Drop
Cable size current carrying capacity aur voltage drop dono ke hisaab se select hoti hai. Standard practice: voltage drop 3-5% se zyada nahi hona chahiye (lighting 3%, power 5%). Derating factors apply karte hain – ambient temperature, grouping, conduit fill.
Lighting → 1.5 sq mm (6A MCB)
Power sockets → 2.5 sq mm (16A/20A MCB)
AC / Geyser → 4.0 sq mm (25A MCB)
Main DB incomer → based on total load current
Gulf sites mein ambient temperature 45°C+ hoti hai – is liye cable derating factor (typically 0.85-0.9) apply karna zaroori hai, warna cable overheating ho sakti hai.
DB (Distribution Board) – Heart of Wiring
Components
- Incomer MCB – main switch/circuit breaker
- RCCB – 30mA for human safety
- MCBs for each circuit – lighting, power, AC etc.
- Neutral & Earth bus bars – separate
Best Practices
- Label every circuit clearly – maintenance ke liye.
- Keep spare ways for future expansion.
- Maintain phase sequence (R-Y-B) for 3-phase.
- Use blank covers on unused slots.
Earthing & Bonding – Safety First
- Earthing – Fault current ko safe path provide karta hai. Earth electrode resistance < 5Ω (ideal).
- Equipotential bonding – All exposed metal parts (pipes, frames) connected to earth – touch voltage hazard khatam.
- Main Earthing Terminal (MET) – near main DB, all earthing conductors converge.
Standards – India aur Gulf
| Standard | Region | Key Points |
|---|---|---|
| IEC 60364 | International | Low voltage installations – wiring, protection, earthing |
| NBC Part 8 | India | Building services – electrical |
| IS 732 | India | Cable colour codes – Red-Yellow-Blue for 3-phase |
| DEWA / KAHRAMAA | UAE / Qatar | Local regulations – often IEC based with specific requirements |
Testing aur Commissioning
- Insulation Resistance (IR) – Minimum 1 MΩ per 1000V (or as per standard).
- Continuity test – Ensure all earth connections intact.
- Polarity test – Phase, neutral correct.
- RCCB testing – Trip time/current verify.
- Documentation – As-built drawings, test reports, material certificates – required for handover.
Gulf Interview – Wiring Pe Sawaal
- Cable size selection for a given load – current + voltage drop + derating.
- DB load distribution – How to balance 3-phase loads.
- Earthing system difference – TN-S, TN-C, TT – basic difference puchhte hain.
- Colour coding – Phase, neutral, earth standard.
- Fire-rated / LSZH cables – kab use karte hain (emergency circuits, public buildings).
Cable Size Calculator Use Karo
Load, length, voltage, temperature daalo – cable size aur voltage drop instantly milega.