1. Purpose of BNBC Electrical Rules
- Ensure safety of people and property
- Prevent electric shock, fire, and system failure
- Standardize installation quality across buildings
🔌 2. Wiring System Requirements
✔ Approved Wiring Types
- PVC insulated cables (common)
- XLPE insulated cables (better for heavy load)
- Armoured cable (for underground / shaft)
👉 BNBC requires:
- Proper insulation
- Fire-resistant properties in critical areas
✔ Conduit System (VERY IMPORTANT)
- Use PVC conduit (concealed wiring) in residential buildings
- Use metal conduit in:
- Industrial buildings
- Fire-risk zones
👉 Rule:
- No loose wiring allowed
- All wiring must be inside conduit/trunking
✔ Routing Rules
- Horizontal/vertical straight lines only
- Avoid diagonal wiring
- Keep distance from:
- Water lines
- Gas pipes
⚡ 3. Circuit Design (Core BNBC Concept)
✔ Separate Circuits
You MUST divide circuits:
- Lighting circuit
- Power socket circuit
- Heavy load (AC, heater, pump)
👉 Why?
To prevent overload and simplify fault isolation.
✔ Load Limitation (Typical Practice from BNBC)
- Lighting circuit: ~800–1000 W max
- Power circuit: ~3000 W max
🧰 4. Switches & Socket Installation
✔ Mounting Height (BNBC Standard)
- Socket outlet: ≈ 250 mm above floor
- Switch board: ≈ 1.2–1.5 m above floor
✔ Socket Rules
- Use 3-pin socket (with earthing)
- Mandatory earthing connection
- Child-safe shutters recommended
⚡ 5. Earthing (CRITICAL – DO NOT IGNORE)
✔ BNBC Requirement
Every building must have:
- Proper earthing system
- Low resistance path to ground
✔ Types Used
- Plate earthing
- Pipe earthing
- Rod earthing (modern)
✔ Purpose
- Prevent electric shock
- Protect equipment
- Enable circuit breaker operation
🔥 6. Protection System
✔ Mandatory Devices
- MCB (Miniature Circuit Breaker)
- MCCB (for large systems)
- RCCB / ELCB (life-saving device)
👉 BNBC strongly emphasizes protection against:
- Overload
- Short circuit
- Earth leakage
⚡ 7. Distribution Board (DB)
✔ Requirements
- Installed in accessible location
- Proper labeling of circuits
- Separate neutral and earth bus
✔ Safety
- Fire-resistant enclosure
- Proper ventilation
⚡ 8. Cable Sizing (Key Engineering Part)
Cable size depends on:
- Load (Ampere)
- Distance
- Voltage drop
👉 Typical residential:
- Lighting: 1.5 mm²
- Socket: 2.5 mm²
- AC: 4–6 mm²
(BNBC requires correct sizing to avoid overheating)
⚡ 9. Installation Safety Rules
✔ BNBC Mandatory Practices
- No exposed joints
- Use junction boxes
- Proper insulation at joints
- Color coding:
- Phase: Red/Brown
- Neutral: Black/Blue
- Earth: Green
⚡ 10. Special BNBC Requirements
✔ Fire Safety
- Fire-resistant cables in escape routes
- Wiring in shafts must be protected (metal conduit/armoured)
✔ Lightning Protection
- Required for tall buildings
- Connected with earthing system
✔ Inspection & Testing
Before energizing:
- Insulation resistance test
- Continuity test
- Earth resistance test
⚠️ Reality Check (Critical Thinking)
Most buildings in Bangladesh claim BNBC compliance but fail in:
- Proper earthing
- Correct cable sizing
- Use of RCCB
👉 That’s where real risk lies—not in theory.