Circuit Breaker Safety in South Africa:
SANS, IEC Standards & Best Practices
Avoid costly risks in low-voltage applications
Designing safe and reliable low-voltage networks is critical for utilities and infrastructure.
Circuit breakers are essential components that play a critical role in safeguarding properties and personnel. Correct circuit breakers prevent damage, fires, and electrical hazards.
An Analysis of Standards, Pitfalls, and Best Practices
TIP: Before choosing a circuit breaker, always confirm whether your application is residential or utility.
The complexity of circuit breaker standards
- There are countless types of circuit breakers in the market.
- They all claim compliance with different international or local standards.
- The standards are not all the same and are not all suitable for high-demand environments.
- In low-voltage reticulation and distribution, do not to choose the wrong standard.
- Choosing the wrong standard can lead to safety failures.
Common referenced standards: Key circuit breaker standards
- IEC 60898 Household Use and similar installations. Not suitable for environments where electrical stress and operating conditions are demanding, such as utility-grade applications and outdoor reticulation.
- IEC 60947-2 Industrial Standard. Designed for circuit breakers used in demanding industrial installations, including low-voltage distribution and reticulation. Handles more demanding, durable electrical capabilities. Handles high voltages, tougher insulation, and stronger surge protection.
- SANS 556 series, South Africa. A local SABS version of IEC 60947-2 with amendments and adaptations to handle Category IV overvoltages and South African conditions.
Misapplication of IEC 60898 Circuit Breakers in Southern Africa
The Danger of Using IEC 60898 in Utility Networks
- Installation of IEC 60898-rated circuit breakers in utility networks with low-voltage reticulation and distribution systems is due to convenience and cost cutting.
- These breakers are for European homes and NOT African reticulation systems.
- Relying on IEC 60898 circuit breakers undermines network safety and security.
- Increased risk of fire, equipment failure, and even injury.
Key Differences in Safety Parameters
The distinction between IEC 60898 circuit breakers and those designed to more stringent standards, IEC/SANS 60947-2 or the SANS 556 series, lies in the permissible clearance and creepage distances.
Key Differences:
| Clearance | Insulation & Surge Tolerance | |
|---|---|---|
| Specification: | IEC 60898 | IEC 60947-2 / SANS 556 |
| Creepage/Clearance: | 3mm | 5mm |
| Impulse Withstand / Voltage: | 4kV | 6kV |
| Testing Conditions: | Basic | Simulated surges, lightning. |
Minimal distances may pass in calm climates, but in South Africa’s high-surge zones, they’re unsafe.
IEC 60898 allows these critical distances between live parts to be as small as 3 mm. Such minimal separations may be adequate in benign, controlled environments, but in more demanding applications where surges, pollution, and condensation are possible, they present a vulnerability.
IEC 60898 requires an impulse voltage withstand testing of only 4 kV (6 kV in IEC/SANS 60947-2 or SANS 556 series). This means that circuit breakers rated to this standard may not endure the sudden voltage spikes, whether from switching operations or lightning surges, that characterise distribution networks, especially in regions with high atmospheric lightning activity such as South Africa.
Why impulse voltage withstands ratings matter
Impulse Voltage Withstand Testing is Not Optional
- South Africa experiences frequent lightning strikes and power surges.
- IEC 60898 doesn’t include enough overvoltage protection.
- Test SANS 556 or IEC 60947-2 breakers for real-world surges, switching operations, and lightning strikes.
- For safety and reliability, choose only breakers marked “Uimp – 6kV” or higher.
These tests simulate what happens during storms, grid switching, and sudden faults. Only use devices that pass in utility-scale systems.
What is Category IV?
South Africa is classified as a Category IV environment, and the standard voltage is 230V.
Category IV overvoltages refer to the highest level of transient voltage surges found at the origin of the electrical installation such as the electricity meter or main distribution board.
Surges (short-duration voltage spikes) are dangerous due to the low impedance of the power grid at this point, which can result in high short-circuit currents.
Category IV explained: Where the risk is highest
- Category IV is the highest risk of electrical surges. Applied to measurement locations near the origin of the electrical installation.
- Incoming service cable from the utility to the building.
- Meter tails from the electricity meter to the main protective device or main distribution board.
- Secondary side of medium-voltage power transformers and the main distribution board nearby.
Recommendations for South African Installations
Best practice to ensure circuit breaker safety: Correct specification, selection, and application of circuit breakers in low-voltage reticulation and distribution systems demand a rigorous, standards-based approach.
- Never install IEC 60898-rated circuit breakers in utility reticulation or distribution/industrial networks. These devices are for domestic and similar environments within Europe only and do not meet the impulse withstand or clearance requirements needed for more demanding applications.
- Use SANS 556 breakers with 6 kV impulse protection for category IV overvoltage environments.
- Insist on independent certification from a trusted lab for all circuit breakers, confirming their ability to withstand upper tolerance power frequency voltages and impulse voltages.
- Pay attention to local surge conditions, including lightning flash density, when specifying protection devices.
- Maintain full documentation for all protection devices.
- Safety is more important than cost. Underspecifying circuit breakers can lead to failure, fire, and even loss of life.
Conclusion
Always adhere to the circuit breaker safety standards in South Africa and insist on robust certification.
Ensure your breakers meet all local South African safety standards. Visit our Membership Directory. Contact Safehouse to speak to an expert. Find out how to become a member today.
Please note all of the above are also applicable to IEC 61009 RCBO’s.