Circuit Wiring Specifications

# Circuit Description Copper Wires & Size Current Rating
1
 Distribution Wiring for Light Point / Fan Point / 6A Plug Point on the board / 6A Independent Plug Point 2 × 1.5 sq.mm. + 1 × 1.5 sq.mm. (E) 16A
2
 Between SPNDB & Switch board & From Spare way of SPNDB to 16A Plug Point / Computer Board 2 × 2.5 sq.mm. + 1 × 1.5 sq.mm. (E) 20A
3
 From 1 way of TPNDB to 30/32 Switch Board [For RAC / Geyser] 2 × 4 sq.mm. + 1 × 2.5 sq.mm. (E) 32A
4
 From 1 way of TPNDB to 30/32 Switch Board [For Higher Capacity RAC] 2 × 6 sq.mm. + 1 × 4 sq.mm. (E) 40A
5
 From 1 way of TPNDB to SPNDB 2 × 6 / 10 sq.mm. + 1 × 4 sq.mm. (E) 50A
6
 From LT Panel / VTPNDB / TPNDB to 32A TPN Incoming Switch / Isolator 4 × 6 sq.mm. + 2 × 4 sq.mm. (E) 32A
7
 From LT Panel / VTPNDB / TPNDB to 40A TPN Incoming Switch / Isolator 4 × 10 sq.mm. + 2 × 6 sq.mm. (E) 40A
8
 From LT Panel / VTPNDB / TPNDB to 63A / 80A TPN Incoming Switch / Isolator 4 × 16 sq.mm. + 2 × 10 sq.mm. (E) 80A

Standard Wire Color Codes

Phase (Live)
Red / Brown / Black
Neutral
Blue / Black
Earth (Ground)
Green / Green-Yellow
Switch Line
Yellow / Purple

Key Points to Remember

  • All wire sizes are for copper conductors as per IS/IEC standards
  • Earth wire size may differ from live/neutral wires as per safety norms
  • Always add 20-25% safety margin for future load expansion
  • Consider voltage drop calculations for long cable runs
  • Use proper cable management and protection (conduit/trunking)

Wire Size Calculator

Calculation Results

Minimum Wire Size Required
2.5 sq.mm
Recommended Wire Size
4.0 sq.mm
Voltage Drop
2.1 %
Current Carrying Capacity
25 Amps
Safety Margin
+56% SAFE

Calculation Notes

  • Calculations based on IEC 60364-5-52 standards for electrical installations
  • Voltage drop should not exceed 3% for lighting circuits and 5% for other circuits
  • Consider derating factors for temperature, grouping, and installation method
  • Always round up to the nearest standard wire size for safety
  • Consult local electrical codes and regulations for specific requirements

Electrical Abbreviations & Terms

sq.mm.
Square millimeters - Cross-sectional area of electrical wire/conductor
(E)
Earth wire - Protective grounding conductor for electrical safety
SPNDB
Single Pole Neutral Distribution Board
TPNDB
Triple Pole Neutral Distribution Board
VTPNDB
Voltage Tolerant / Triple Pole Neutral Distribution Board
LT Panel
Low Tension Panel - For voltages up to 1000V AC
TPN
Triple Pole and Neutral - 3-phase circuit with neutral
RAC
Room Air Conditioner
MCB
Miniature Circuit Breaker - Overcurrent protection device
RCCB
Residual Current Circuit Breaker - Earth leakage protection
ELCB
Earth Leakage Circuit Breaker - Older term for RCCB
DB
Distribution Board - Contains circuit protection devices

Common Wire Size Standards

  • 1.0 sq.mm - For control circuits and small loads up to 10A
  • 1.5 sq.mm - Standard for lighting circuits (up to 16A)
  • 2.5 sq.mm - Standard for socket outlets (up to 20A)
  • 4.0 sq.mm - For air conditioners, geysers (up to 32A)
  • 6.0 sq.mm - For sub-main circuits and larger ACs
  • 10.0 sq.mm - For main supply and heavy appliances
  • 16.0 sq.mm - For high current applications and industrial use

Electrical Safety Standards & Guidelines

Critical Safety Warnings

  • Always disconnect power before working on electrical circuits
  • Use proper PPE (Personal Protective Equipment) - insulated gloves, safety glasses
  • Never overload circuits beyond their rated capacity
  • Ensure proper earthing for all electrical installations
  • Regular inspection and maintenance of electrical systems is mandatory
  • Use only certified electrical components and materials

Installation Checklist

  • ✓ Verify wire size matches circuit requirements
  • ✓ Check proper color coding of wires
  • ✓ Ensure secure connections with proper torque
  • ✓ Test insulation resistance before energizing
  • ✓ Verify earth continuity and resistance
  • ✓ Check polarity of all connections
  • ✓ Test RCCB/ELCB operation
  • ✓ Verify circuit labeling and documentation

Regulatory Compliance

  • Follow National Electrical Code (NEC) / IS standards
  • Adhere to local electrical regulations and bylaws
  • Obtain necessary permits and approvals
  • Use only licensed electricians for installation
  • Maintain proper documentation and test certificates
  • Regular safety audits and inspections