12
Full Consumer Unit (3-Circuit Panel)
Build a complete home breaker panel using a Distribution Board. Three independent circuits — lighting, sockets, and a motor — each protected by their own MCB.
Components Needed
Text Wiring Path
Live → DB (L-in) → L1 → MCB1 → Switch → Bulb
→ L2 → MCB2 → 3-Pin Socket
→ L3 → MCB3 → Motor
Neutral → DB (N-in) → N1/N2 → (all returns)Schematic
Steps
- 1Place a Live terminal, Neutral terminal, and a Distribution Board.
- 2Wire: Live → DB L-in. Wire: Neutral → DB N-in.
- 3Circuit 1 (Lighting): DB L1 → MCB1 → Switch → Bulb → DB N1.
- 4Circuit 2 (Sockets): DB L2 → MCB2 → 3-Pin Socket (L) → DB N1.
- 5Circuit 3 (Motor): DB L3 → MCB3 → Motor (L) → DB N2.
- 6Press Run — all three circuits operate independently.
- 7Trip MCB2 — only the socket goes dead. Lighting and motor stay running.
Key insight
The key principle of a consumer unit is circuit isolation: a fault on one circuit trips only that MCB, leaving all other circuits unaffected. This is why each circuit has its own dedicated breaker.
⚠ Safety practice
A consumer unit carries live busbar and main-switch terminals even with every breaker off. Only a competent person should remove a cover, and the supply must be isolated at the cut-out first.
Terms used here
Defined in the glossary — each one opens at its own entry.
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