Type A RCBO vs Type AC RCBO: What’s the Difference and Which One Should You Choose?

What Is an RCBO?

An RCBO (Residual Current Breaker with Overcurrent Protection) combines:

• Overload protection (like an MCB)
• Short circuit protection
• Earth leakage protection (like an RCCB)

Unlike traditional protection combinations, RCBO breakers provide all three protections in one compact device, improving safety and saving space in distribution boards.

Learn more about different types of RCBO breakers and their applications.

Understanding Residual Current Types

The key difference between Type A and Type AC lies in what kind of leakage current they can detect.

Electrical leakage is not always pure AC anymore. Modern appliances generate more complex current waveforms due to electronic components.

That’s where the distinction becomes important.

What Is a Type AC RCBO?

Detection Capability:

Type AC RCBO detects: pure sinusoidal alternating current (AC) residual currents only.

Typical Applications:

• Traditional resistive loads
• Lighting circuits
• Water heaters
• Simple socket outlets without electronics

Limitation:

It cannot reliably detect pulsating DC leakage currents. This becomes a safety concern in installations where electronic devices are used.

What Is a Type A RCBO?

Detection Capability:

Type A RCBO detects:

• Pure AC residual current
• Pulsating DC residual current

This makes it suitable for modern installations.

Typical Applications:

• Washing machines
• Induction cookers
• LED lighting
• Air conditioners
• EV chargers (in some configurations)
• Circuits with electronic power supplies

Because many modern appliances use rectifiers and switching power supplies, pulsating DC leakage can occur. Type A is designed to respond to these fault conditions.

Key Differences: Type A vs Type AC RCBO

Why Type A Is Becoming the New Standard

In many countries, electrical standards increasingly recommend or require Type A devices in residential and commercial buildings.

Why?

Because modern electrical loads are no longer purely resistive. Even simple household appliances contain electronic control boards that may generate pulsating DC leakage.

Using Type AC in such environments may result in:

• Failure to detect certain faults
• Reduced protection reliability
• Potential safety risks

For new installations, many professionals now consider Type A as the safer and more future-ready choice.

When Is Type AC Still Acceptable?

Type AC may still be used when:

• The circuit supplies purely resistive loads
• No electronic equipment is connected
• Local standards allow its use

However, for mixed-load environments (which are common today), upgrading to Type A is generally advisable.

How to Choose Between Type A and Type AC?

Ask these questions:

1. Does the circuit power electronic devices?
2. Are there inverter-based appliances?
3. Is future expansion expected?
4. Do local electrical codes require Type A?

If the answer to any of these is “yes,” Type A is usually the better option.

Final Thoughts

Both Type A and Type AC RCBO devices provide essential protection against overload, short circuit, and earth leakage. However, the key difference lies in their sensitivity to different residual current waveforms.

As electrical systems continue to evolve, Type A RCBO is becoming the preferred solution for safer and more reliable protection.

If you’re selecting protection devices for residential, commercial, or industrial projects, explore our full range of RCBO breakers to find the right specification for your application.