These devices solve different problems. The safest useful design comes from the actual circuits and supply—not from adding the longest list of abbreviations to a quotation.
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Three abbreviations, three different decisions
RCD is the wider family of residual-current devices. In a grouped arrangement an RCCB may protect several circuits, while an RCBO combines residual-current and overcurrent protection for one circuit. An SPD limits transient overvoltage. None replaces correct earthing, bonding, circuit design or fault repair.
Start with the property, not the product
The board layout affects fault separation, diagnosis and how much of the home loses power when a device operates.
Swipe through the four questions
01
RCCB / grouped RCD
An RCCB can provide residual-current protection to several circuits while separate devices provide overcurrent protection. A fault on one may disconnect the whole group, depending on the arrangement.
02
RCBO
An RCBO combines overcurrent and residual-current protection, allowing circuit-level separation and clearer fault identification.
03
SPD
An SPD is intended to limit short-duration voltage surges. It is not a substitute for an uninterrupted power supply or a guarantee against every damaging event.
04
Type selection
Modern electronic loads can influence the type of residual-current device selected. The design should reflect the actual circuits and equipment.
A practical decision guide
Two boards with the same number of ways can behave very differently during a fault.
Grouping
Grouped RCD arrangements may be economical but can disconnect several healthy circuits when one circuit develops leakage.
Separation
Circuit-level devices can improve continuity and diagnosis, though the correct device characteristics still depend on the circuit.
Surge decision
The designer considers the installation, connected equipment and current requirements when deciding the SPD arrangement.
Existing faults
Circuit testing before replacement helps identify problems that may prevent immediate reconnection to the new devices.
What professional work looks like
A good board schedule explains how each final circuit is protected.
Confirm circuit purpose, conductor arrangement, load and existing protective device.
Test continuity, insulation, polarity and relevant protective measures before transfer.
Choose RCD type, overcurrent rating and breaking characteristics to suit the verified design.
Consider how faults affect continuity and what transient protection the installation requires.
Verify installed devices, complete the schedules and explain the test-button routine to the customer.
Experience made visible
Brand, module count and marketing labels do not establish suitability. The certificate and circuit schedule should show what was installed and how it relates to the property.
This guide explains the practical issues customers ask about. Regulations and official guidance can change, and the correct solution still depends on the property. The following primary sources were checked when this page was prepared:
Straight answers to the questions customers ask before arranging a survey or inspection.
They are not direct alternatives in every context. An RCBO protects an individual circuit against overcurrent and residual current, while an RCD may provide residual-current protection to a group. The complete board design determines the practical difference.
No. An SPD limits transient overvoltage; it does not provide backup power. A UPS or other standby arrangement addresses continuity for selected equipment.
The circuit may have insulation leakage, shared or borrowed conductors, connected equipment leakage or another defect. Pre-work testing helps identify these issues before transfer.
Yes. RCD or RCBO protection does not replace the required earthing and bonding arrangements or correct circuit design.
Send the property details and, if useful, a photograph of the existing board after submitting. We test the existing installation before confirming the design.
We inspect the property and existing installation before specifying work.
The quotation separates verified work from assumptions and optional improvements.
The completed work is tested and documented for its actual scope.
You know what is included, what remains and who controls the finished system.
