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RCBO vs MCB vs RCD: Differences & WCED Buying Guide

RCDs & RCBOs

RCBO vs MCB vs RCD: Differences & WCED Buying Guide

Understand what each protective device does, how to read its ratings and how to find the right WCED breaker for a consumer unit or three-phase distribution board.

EcoHarmony buying guide · Updated 1 November 2026

The short answer

An MCB provides overload and short-circuit protection. An RCCB, often called an RCD, detects residual current but has no integral overcurrent protection. An RCBO combines both functions. None of these names, by itself, means the device includes surge protection or open-PEN fault detection.

What is the difference?

Device Function What to check separately
MCB Overload and short-circuit protection Required residual-current protection
RCCB / standalone RCD Residual-current protection Overcurrent protection and coordination
RCBO Overcurrent and residual-current protection RCD type, trip curve, rating and compatibility
SPD Limits transient overvoltages Does not replace an MCB, RCBO or PEN device

RCD is a general term for residual-current protection. In a shopping list it often means a standalone RCCB. Ask which complete device is intended so that an RCD is not ordered in place of an RCBO.

Read the five ratings before buying

A marking such as C32, 30mA, Type A and 10kA describes five different characteristics. C is the overcurrent curve, 32A is the rated current, 30mA is the residual operating-current rating, Type A describes residual-current waveforms and 10kA is the short-circuit breaking capacity. A 40A device is not a universal upgrade for a 32A circuit.

Match the current rating and curve to the circuit design, the residual-current type to the equipment, and the breaking capacity to the prospective fault current and manufacturer’s coordination information. Also check the pole arrangement, neutral switching, terminals and board compatibility.

Individual RCBOs or an MCB with a shared RCD?

Individual RCBOs can reduce the number of circuits lost when one circuit develops a residual-current fault. A shared RCD may disconnect several circuits together. Actual selectivity still depends on the upstream devices and installation design, so an individual RCBO is not a promise that nothing else can trip.

For a replacement, do not choose solely by physical fit. The board manufacturer’s permitted device range, busbar engagement and assembly ratings matter.

Which WCED range should I open?

For a complete assembly, compare TPN boards or PME protection units. Buying a breaker alone does not provide the enclosure or all the protection those assemblies may contain.

WCED models and exact product options

Choose a configuration below to open that option on the product page. Check the selected specification, current price and availability before adding it to your basket.

WCED 1-Pole 10kA RCBOs for TPN Distribution Boards
WCED 40A 2-Pole 30mA Type A RCBO (Type A RCCB, C Curve MCB)

Common buying questions

Does an RCBO include surge protection?

No. Residual-current and overcurrent protection are different functions from an SPD. A fitted consumer unit may contain both, but check its component list.

Will a 10kA RCBO stop nuisance tripping?

10kA describes short-circuit breaking capacity. It does not explain or cure unwanted residual-current tripping. Have the fault investigated before replacing or changing a device.

Can I replace an MCB with any RCBO?

Only where the board and installation permit the exact replacement. Space, neutral connections, terminals and assembly compatibility all need checking.

Do B and C curves mean Type B and Type C RCDs?

No. B and C overcurrent curves are separate from Type A, F or B residual-current classifications. See the RCBO types guide.

Need help finding the listed part?

Send EcoHarmony the equipment model, existing board model and the specification provided by your electrician. We can help identify the matching listed product and obtain further product information. Your installer must confirm suitability for the installation.

Ask a product question · Browse WCED products

Related guides

Manufacturer information and further reading

This is a product-selection guide, not installation instructions. Use the exact model’s current manufacturer instructions and the applicable installation requirements for final selection.

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