If you’ve had an electrician mention RCDs or RCBOs, or you’ve seen them listed on a quote and thought, “what are those things and why do I need them?” — you’re not alone.
Here at EPM, we know electrics can sound like alphabet soup sometimes. But when it comes to protecting your home and family, understanding the difference between these two components is genuinely useful — especially if you’re upgrading your consumer unit or planning other electrical work.
Let’s break it down in plain English.
What Is an RCD?
RCD stands for Residual Current Device. Its job? To protect you from electric shock.
It constantly monitors the flow of electricity in a circuit. If it detects a fault — like current leaking to earth because someone touched a live wire or a damaged appliance — it cuts the power in milliseconds.
So, if a faulty kettle or exposed cable puts you at risk, the RCD steps in fast to prevent injury (or worse).
In most older consumer units, you’ll see two RCDs protecting multiple circuits — like upstairs sockets, downstairs lighting, etc. It works… but it’s not perfect.
What’s an RCBO, Then?
RCBO stands for Residual Current Breaker with Overcurrent protection.
Think of it as a combined RCD and MCB (Miniature Circuit Breaker) all in one device. An RCBO does everything an RCD does — protecting people — plus it adds circuit-specific protection against overloads and short circuits.
And here’s the kicker: RCBOs protect individual circuits. So if one trips, only that one circuit goes off — not half the house.
So… RCD or RCBO? What’s Better?
Short answer? RCBOs are the modern standard.
Here’s a quick comparison:
| Feature | RCD (with MCBs) | RCBO |
|---|---|---|
| Type of Protection | Earth faults only | Earth faults + overload |
| Circuits Covered | Multiple circuits per RCD | One RCBO per circuit |
| Fault Isolation | Several circuits trip at once | Just the faulty circuit trips |
| Safety & Convenience | Basic | Higher |
| Cost | Lower upfront | Slightly more per circuit |
If you’re upgrading your consumer unit in 2025, most electricians — including us — will recommend individual RCBOs for every circuit. It’s safer, more reliable, and reduces disruption if there’s ever an issue.
Why Does This Matter for Exeter Homeowners?
We’ve replaced plenty of old fuse boxes in and around Exeter where either:
There was no RCD at all (usually with rewireable fuses)
One fault knocked out multiple circuits
Or even worse… the RCD wasn’t working properly
RCBOs give us more control, better fault-finding, and better protection for your home.
What If You Already Have RCDs?
You’re not necessarily in danger — but if you’re planning a renovation, adding new circuits, or your consumer unit is due for replacement, it’s the perfect time to upgrade to RCBOs.
In fact, most modern consumer units now come RCBO-ready.
Final Thought from EPM
Whether you’re a homeowner in Exeter looking to upgrade your electrics or just curious about what’s inside that grey box under the stairs — understanding RCDs and RCBOs helps you make better, safer decisions.
If you’re not sure what your home currently has — or if it’s time for an upgrade — we’re happy to pop over, have a look, and give you honest advice.
No pressure. No pushy sales. Just proper answers.
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