Upgrading my board — should I ask for RCBOs on every circuit, or one RCD with MCBs?

Short answer: an RCBO is one device that combines an RCD (earth-leakage protection, the life-saving bit) and an MCB (overload/short-circuit protection) for a SINGLE circuit. The modern, better layout is RCBOs per circuit: if one circuit develops an earth fault, only THAT circuit trips. The older/cheaper layout puts one shared RCD in front of a whole bank of MCBs — so a single earth fault on any circuit trips the RCD and kills EVERYTHING on it at once (half the house goes dark), and it's harder to find the culprit. RCBOs cost more but give you far better discrimination and fewer whole-board blackouts. For an upgrade, RCBOs (or at least splitting circuits across several RCDs) is what I'd ask for.

The difference, plainly: - RCD: detects earth leakage (current going where it shouldn't — the shock/fire risk) and cuts off. Doesn't protect against overload. - MCB: trips on overload/short circuit. Doesn't protect against earth leakage. - RCBO: both, in one module, for that one circuit.

Day to day (this is what you'll actually notice): - RCBOs per circuit: a fault on the fridge circuit trips only the fridge circuit — the rest of the house stays on, and you know instantly which circuit is at fault. Best convenience and safest granularity. - One RCD + bank of MCBs: an earth fault anywhere under that RCD trips the whole bank — lights, sockets, several rooms all die together, and you're left guessing which appliance did it (that's the "everything went off at once" scenario). Cheaper up front, more disruptive and harder to diagnose.

Cost vs benefit: - RCBOs cost more (a device per circuit) but you get selective tripping, easier fault-finding, and no whole-house blackout from one fault. On a villa with lots of circuits (and a freezer/AC you don't want dying silently under a shared RCD), that's usually worth it. - A middle ground is dual-RCD/split-load (two RCDs each covering half) — better than one, not as good as full RCBOs.

Common mistake: taking the cheapest single-RCD board and then living with the whole house tripping every time one appliance leaks. Since you're upgrading anyway, ask an electrician to price the board as full RCBOs (or at least split RCDs) and decide with the numbers in front of you. Anyone switched to RCBOs and stopped the whole-house trips?