LANX RCBO vs RCD: What’s the Difference Between RCD and RCBO?

You’re at the switchboard with a circuit that needs residual-current protection, and the choice comes down to two familiar options: an RCD with separate overcurrent protection, or an RCBO that combines both functions. The difference matters because the devices protect against different faults and affect how the circuit behaves when something goes wrong.

The practical question is not simply rcbo vs rcd as a product comparison. It is whether the circuit needs residual-current protection only, or residual-current protection together with overload and short-circuit protection in the same device. For broader context on the products available in this family, see the LANX electrical range.

RCBO vs RCD: What Actually Changes?

The easiest way to separate the two is to look at the protection functions built into each device.

An RCD monitors for an imbalance between current flowing out and returning through the circuit. When residual current reaches the device’s operating threshold, it disconnects the circuit. It is therefore focused on residual-current protection rather than protecting the conductors from overload or short circuit.

An RCBO adds overcurrent protection to that residual-current function. In practical terms, it combines the job normally associated with an RCD and an MCB into one protective device. That distinction is the key to understanding the difference between rcd and rcbo.

What Does an RCD Protect Against?

An RCD is there to detect residual current. That makes it a safety device for faults where current is escaping from its intended path, such as a leakage fault associated with insulation failure or contact with an unintended conductive path.

What it does not do is protect the circuit from every type of overcurrent event. An RCD does not replace an MCB for overload and short-circuit protection. Where those protections are required, the circuit still needs appropriate overcurrent protection alongside the RCD.

That distinction is worth keeping clear when checking an existing switchboard or planning a new circuit. The protection arrangement has to be assessed as a complete circuit, not by looking at one device in isolation.

What Does an RCBO Protect Against?

An RCBO combines residual-current protection with overcurrent protection. That means the same device can respond to residual-current faults while also providing protection against overload and short circuit, subject to its specified ratings and characteristics.

This combination can make circuit protection more straightforward where each individual final circuit needs its own residual-current protection. It also means a fault on one protected circuit can be isolated without relying on one shared residual-current device to cover several downstream circuits.

LANX’s current RCBO selection illustrates this integrated approach. The LANX 20A single-pole RCBO, for example, is specified as a 20A 1P RCBO with 30mA Type A detection and 6kA breaking capacity. The exact rating and configuration still need to match the circuit and installation requirements.

Which One Do You Need?

The buying decision becomes much easier once the circuit is considered first.

Use an RCD arrangement when separate overcurrent protection is already provided

An RCD can make sense where the protection design already includes suitable MCB or other overcurrent protection for the circuit. In that arrangement, the devices have separate jobs: the MCB handles overload and short circuit, while the RCD handles residual current.

The advantage is flexibility in how the switchboard is configured, particularly where an existing board already uses a separate RCD arrangement. The important point is that the complete protection scheme must still provide the required functions for the circuit.

Use an RCBO when combined protection is the cleaner circuit-level solution

An RCBO is often the more direct choice when the circuit needs both overcurrent and residual-current protection and you want those functions integrated into one device. This can be particularly useful where individual circuit protection is preferred or switchboard space is a consideration.

It also changes fault isolation. With individual RCBO protection, a fault on one circuit can trip that circuit’s protective device rather than necessarily disconnecting several downstream circuits through a shared RCD arrangement.

Do not choose the device before checking the installation

The right choice depends on more than whether the product says RCD or RCBO. Check the circuit arrangement, conductor protection, rated current, pole configuration, residual-current characteristics, breaking capacity and the requirements that apply to the installation.

For example, choosing a 20A RCBO does not mean the circuit should automatically be protected at 20A. The protective-device rating must be appropriate for the cable, installation conditions and circuit design. For the MCB side of that selection process, the Lanx MCB rating guide covers how current rating and circuit conditions affect breaker selection.

A Practical Switchboard Decision

Consider a new final circuit where residual-current protection is required and the board is being configured circuit by circuit. The first question is whether you need both residual-current and overcurrent protection for that circuit.

If the answer is yes, an RCBO provides both functions in one device. You then select the appropriate current rating, poles, residual-current characteristics and breaking capacity for the installation.

If the switchboard already uses a suitable RCD arrangement and separate MCB protection, an RCD may still be the appropriate part of that overall design. The important distinction is that an RCD should not be treated as a replacement for the circuit’s required overcurrent protection.

Common Mistakes When Comparing RCBO and RCD

• Assuming an RCD replaces an MCB. An RCD provides residual-current protection; it does not provide the same overload and short-circuit protection as an MCB.
• Choosing an RCBO by amp rating alone. Rated current is only one part of the selection. Pole arrangement, residual-current characteristics and breaking capacity also need checking.
• Ignoring the circuit design. The right device depends on the complete protection arrangement, conductor protection and installation conditions.
• Treating all RCBOs as interchangeable. Two RCBOs can have different pole configurations, breaking capacities or residual-current characteristics even when they share the same amp rating.
• Using the wrong protection type for the application. Type and sensitivity should be selected from the equipment and installation requirements rather than assumed from a generic “RCBO” label.

Frequently Asked Questions

RCBO vs RCD Basics

What is the difference between RCD and RCBO?

An RCD provides residual-current protection, while an RCBO combines residual-current protection with overcurrent protection for overload and short circuit. An RCD therefore normally forms part of a protection arrangement that also includes suitable overcurrent protection.

Can an RCD replace an RCBO?

Not as a direct one-for-one substitution. An RCD and RCBO perform different protection functions, so replacing one with the other depends on the complete circuit design and the protection already provided elsewhere.

Circuit Selection

What type of RCBO suits a 20A single-pole circuit?

A product such as the LANX LX620G2 20A RCBO is specified as a 1P 20A device with 30mA Type A detection and 6kA breaking capacity. The final selection must still match the circuit design and installation requirements.

Does an RCD protect against short circuit?

No. An RCD is intended for residual-current protection. Short-circuit and overload protection requires appropriate overcurrent protection, such as an MCB or the overcurrent function incorporated into an RCBO.

Australian Installation Requirements

Does replacing an RCBO require a licensed electrician in NSW?

Electrical wiring work in NSW must be carried out by, or under the supervision of, a licensed electrician. Switchboard protection work should therefore be handled within the applicable licensing and compliance requirements for the job.

Is 30mA always the correct RCD or RCBO sensitivity?

No device rating should be selected automatically from a general rule. Residual-current sensitivity must be appropriate to the circuit, equipment and applicable installation requirements. Check the specific job rather than assuming one sensitivity suits every application.

Shop rcbo vs rcd at Schnap

LANX RCBO options are available with trade pricing and same-day dispatch from the Kingsgrove NSW warehouse. Check the individual product specifications before ordering to make sure the configuration matches the circuit.

• RCBO 1P 20A 6kA Breaking Capacity 30mA Sensitivity Type A LANX LX620G2 — View product

• RCBO 2P 20A 4.5kA Breaking Capacity Type A Short Circuit Protection LANX LA220 — View product

Need the right rcbo vs rcd for the job? Browse the LANX range at Schnap.