Basic Electric

Single Phase and Three Phase Wiring

1. Single Phase Wiring

Single phase wiring is commonly used in homes, small shops and small electrical loads.

Main wires:

• Phase (L) – carries electrical supply
• Neutral (N) – completes the circuit
• Earth (E) – provides safety against electric shock

Simple diagram:

      Supply
        │
     Phase (L)
        │
      MCB
        │
      Switch
        │
      Load
     (Bulb/Fan)
        │
     Neutral (N)
        │
      Supply

Earth (E) ─────────→ Metal body of equipment

Examples: Fan, bulb, TV, computer, small motor.

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2. Three Phase Wiring

Three phase wiring is mainly used for industries, workshops, large motors and heavy electrical loads.2. Three Phase Wiring

Three phase wiring is mainly used for industries, workshops, large motors and heavy electrical loads.

Main wires:

• R – Phase 1
• Y – Phase 2
• B – Phase 3
• N – Neutral (when required)
• E – Earth

R ─────┐
Y ─────┼──→ 3 Phase Load / Motor
B ─────┘
N ─────────→ Neutral (if required)
E ─────────→ Earth

For a three-phase motor:

R ─────────┐
Y ─────────┼──→  3 Phase Motor
B ─────────┘
E ───────────→ Motor Body

Main Difference

Single Phase	Three Phase
1 phase + neutral	3 phases
Used in homes	Used in industries/workshops
Suitable for small loads	Suitable for heavy loads
Simple wiring	More complex wiring
Example: fan, bulb	Example: industrial motor

Easy way to remember:
👉 Single Phase = Home & small load
👉 Three Phase = Industry & heav