Cable Selection Basics for Electrical Installations (SANS 10142 Guide)
Introduction
Cable selection is a core part of the Installation Rules Paper 2 exam. Candidates are expected to know how to select cables based on current carrying capacity, voltage drop, installation method and SANS 10142‑1 tables. The syllabus lists cable selection under both installation requirements and calculations. Cable sizing, cable installation and current carrying capacity as core SANS 10142 competencies.
1. Current Carrying Capacity
Select the cable so that its continuous current rating exceeds the design current and ensures safety and compliance. Past exam papers reference this through conductor resistance and cable rating tables.
2. Voltage Drop
Voltage drop must remain within acceptable SANS limits. Paper 2 exam questions often require cable choice justification based on a cable Voltage Drop. Voltage drop calculations are frequently tested in the exam. You can learn more in our detailed guide on Installation Rules calculations and exam preparation .
3. Installation Method
Depending on whether a cable is buried, clipped, ducted or inside conduit, correction factors may apply.
4. Conductor Size
Conductor sizing may depend on:
- Current
- Resistivity
- Distance
- Fault conditions
- Environmental conditions
If you are preparing for the Installation Rules examinations, read our detailed Installation Rules Exam Guide to understand the structure of Paper 1 and Paper 2.
Frequently Asked Questions
What factors determine cable selection?
Cable selection depends on current carrying capacity, voltage drop, installation method and environmental conditions.
Why is voltage drop important in cable selection?
Voltage drop affects the performance and safety of electrical installations. SANS 10142 limits voltage drop to ensure equipment operates correctly.
What tables are used for cable sizing in SANS 10142?
Cable sizing is typically determined using current carrying capacity tables, installation method correction factors and conductor resistance values.
Start Your Installation Rules Exam Preparation Today
Passing the Installation Rules Exam in South Africa requires more than reading SANS 10142 — it requires structured preparation and realistic exam practice. Our Installation Rules Study Guide is designed specifically for South African electricians and it includes: Realistic exam-style questions, clear and practical explanations, focus on high-weight SANS 10142 sections. If you are serious about passing on your first attempt, start preparing strategically today. The exam rewards strategic preparation — not last-minute cramming.
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What You Will Learn
You will learn how to:- 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