DB Layout, Cable Selection & Protection – Installation Rules Exam Guide
Introduction
This guide covers everything electricians need for Paper 2: Distribution Board layout, protection devices, cable selection, fault level calculations, verification, and SANS 10142 compliance.
1. Protection Devices
DBs include circuit-breakers, fuses, Earth Leakage Units, and surge protective devices.
2. Circuit Arrangements
Arrange circuits to balance load across phases. This is a key Paper 2 exam topic for multi-phase systems. Learn more in our Installation Rules calculations guide.
3. Fault Level & PSCC
PSCC calculations ensure protective devices can handle fault currents. This prevents device failure and electrical hazards.
4. Cable Selection Basics
Cables must be selected for:
- Current carrying capacity
- Voltage drop limits
- Installation method (clipped, ducted, buried)
- Conductor size, resistivity, distance, fault conditions, environment
For full details, see our Installation Rules Exam Guide.
5. Neutral & Earth Arrangements
- Neutral size often matches phase conductors
- Neutral must remain unbroken where required
- Earth bars centralize earthing connections
6. Labelling & Safety
Clear labelling of circuits, devices, and supply characteristics is mandatory for safety and exam compliance.
DB Layout & Cable Selection Infographic
Frequently Asked Questions – DB Layout & Cable Selection
A DB distributes electrical power to multiple circuits, provides overcurrent protection via breakers or fuses, and ensures safe isolation for maintenance.
Cable sizing depends on the design current, installation method, voltage drop limits, and conductor resistivity. SANS 10142-1 tables provide guidance.
PSCC (Prospective Short Circuit Current) determines the maximum fault current a protective device must handle without failure. Correct calculations prevent device damage and hazards.
Neutral conductors often match phase conductors in size and must remain unbroken in critical joints. Earth bars provide a single point for earthing connections, ensuring safety.
Start Your Installation Rules Exam Preparation Today
Passing the Installation Rules Exam requires structured preparation and realistic practice. Our Study Guide includes exam-style questions, explanations, and focus on high-weight SANS 10142 sections.
👉 Start preparing smarter today and increase your chances of passing on your first try.
Start Your Installation Rules Exam Preparation Today
What You Will Learn
- Interpret and apply the OHS Act and Electrical Installation Regulations
- Calculate Voltage Drop, PSCC (AC & DC), Touch Voltage correctly
- Perform inspection, testing, verification, and complete CoC tasks
- Master SANS 10142‑1 installation requirements
- Work under exam time pressure