Case Study: Small Retail Shop Switchboard

Version 1.0

1. Project Overview

This case study demonstrates the complete drafting workflow for a small commercial retail shop.

The objective is to convert the engineer's Design Intent into a complete manufacturing drawing package.

Although this is a simplified example, the workflow follows the same process used in real switchboard drafting projects, and strictly follows the Input & Output Specification.

2. Input Documents

2.1 Design Specification

Project:
Small Retail Shop

Supply:
400V 3 Phase 50Hz

Main Protection:
63A 4 Pole MCCB

Board Type:
Wall Mounted

IP Rating:
IP42

Cable Entry:
Top Entry

Standards:
AS/NZS 3000
AS/NZS 61439

2.2 Single Line Diagram

Incoming Supply
       |
    63A MCCB
       |
-----------------------
|         |          |
20A      32A       25A
Light    Power      HVAC

2.3 Equipment Schedule

Item	Manufacturer	Model
Main MCCB	Schneider	EZC100
MCB	Schneider	Acti9
RCBO	Schneider	Acti9 RCBO

2.4 Load Schedule

Circuit	Protection
Lighting	20A MCB
General Power	32A RCBO
HVAC	25A MCB

2.5 Site Information

Location:
Retail Shop

Mounting:
Wall Mounted

Cable Entry:
Top

Maximum Width:
800mm

Maximum Height:
1200mm

2.6 Applicable Standards

AS/NZS 3000
AS/NZS 61439

3. Output Documents

3.1 Single Line Diagram

Result

Incoming Supply
       |
    63A MCCB
       |
 Main Busbar
       |
-----------------------
|         |          |
20A      32A       25A
Light    Power      HVAC

Drafting Outline

1. Read the Design Specification.
2. Confirm incoming supply.
3. Place the main MCCB.
4. Draw the main busbar.
5. Add all outgoing protection devices.
6. Label each circuit.

3.2 General Arrangement Drawing

Result

Front View

+----------------------+
|      63A MCCB        |
|----------------------|
|20A|32A|25A           |
|MCB|RCBO|MCB          |
|----------------------|
| Terminal Blocks      |
+----------------------+

600W × 800H × 250D

Drafting Outline

1. Select cabinet size.
2. Position the main switch.
3. Arrange DIN rail devices.
4. Reserve cable space.
5. Add dimensions.

3.3 Internal Layout Drawing

Result

Door

MCCB

DIN Rail

MCB RCBO MCB

Terminal Blocks

Top Cable Entry

Drafting Outline

1. Place all devices.
2. Check maintenance clearance.
3. Add DIN rails.
4. Add terminal blocks.
5. Add cable routing.

3.4 Manufacturing Drawing

Result — Contains:

• Door cut-outs
• Mounting holes
• DIN rail dimensions
• Cable entry plate
• Busbar mounting

Drafting Outline

1. Measure device dimensions.
2. Create mounting holes.
3. Define cut-outs.
4. Add fabrication dimensions.

3.5 Wiring Diagram

Result

MCCB
 |
Busbar
 |
20A MCB ---- Lighting

32A RCBO --- General Power

25A MCB ---- HVAC

Drafting Outline

1. Assign terminal numbers.
2. Create wire numbers.
3. Connect devices.
4. Verify continuity.

3.6 Bill of Materials

Result

Qty	Description	Model
1	63A MCCB	Schneider EZC100
1	20A MCB	Acti9
1	32A RCBO	Acti9 RCBO
1	25A MCB	Acti9

Drafting Outline

1. Count all devices.
2. Verify manufacturer.
3. Record model numbers.
4. Generate BOM.

3.7 Cable Schedule

Result

Cable	From	To	Size
C01	Supply	MCCB	16 mm²
C02	MCCB	Lighting	4 mm²
C03	MCCB	Power	6 mm²
C04	MCCB	HVAC	4 mm²

Drafting Outline

1. Identify every cable.
2. Assign cable numbers.
3. Record cable sizes.
4. Define cable destinations.

4. Summary

This case study demonstrates the complete drafting process:

Design Specification
   ↓
Single Line Diagram
   ↓
Equipment Selection
   ↓
General Arrangement
   ↓
Internal Layout
   ↓
Manufacturing Drawing
   ↓
Wiring Diagram
   ↓
Bill of Materials
   ↓
Cable Schedule

This workflow represents the standard drafting process used by Shan Electrical Engineering Ltd for small switchboard projects and serves as the foundation for larger commercial and industrial switchboards.