Consumer Unit Upgrades in FleetExtra Ways, Surge Protectionand Better RCD Cover

Where a board has run out of spare ways, there are two realistic options: fit a larger consumer unit in place of the existing one, or add a second, smaller consumer unit alongside it fed from the same supply. Which makes sense depends on the main protective device rating, the space available, and how many additional circuits are actually needed.

A second unit alongside the existing board is often the quicker, less disruptive option where only one or two extra circuits are needed and the existing board is otherwise sound. Replacing with a larger single board makes more sense where several additions are planned or where the existing board has other issues worth addressing at the same time, at which point the conversation moves toward a consumer unit replacement rather than a pure upgrade.

A surge protection device is fitted at the consumer unit and works by diverting transient overvoltage away from the circuits it protects, clamping the voltage seen downstream to a safe level before it reaches appliances. It reacts in microseconds to events such as lightning-induced surges on the supply network or large inductive loads switching nearby.

SPDs are increasingly considered essential in properties with sensitive electronics, renewable energy equipment, or smart home systems, since a single surge event can damage several devices simultaneously. Retrofitting one to an existing board that has spare space is usually straightforward; where space is tight, it may need to be considered alongside adding ways or a board swap.

Where a board already uses individual RCBOs throughout, targeted upgrades are usually about type rather than arrangement, swapping a specific RCBO for a Type A version where a newly connected appliance requires it, for example. Where a board still uses a shared RCD arrangement, converting the most critical circuits to individual RCBOs can be done selectively without touching the rest of the board.

This kind of partial upgrade is judged on a case-by-case basis: sometimes it makes clear sense to isolate one circuit properly; other times, the condition of the rest of the board means a full replacement is the more honest recommendation, and that will be said plainly rather than left unmentioned.

During an upgrade assessment, it sometimes becomes clear that the existing board itself, not just its capacity or RCD arrangement, is the limiting factor, for example a plastic enclosure, degraded terminals, or a main switch rated too low for the load now being asked of it. When that happens, you are told directly rather than having an upgrade forced onto a board that is not a sound base to build on.

In that situation the honest recommendation moves to a consumer unit replacement, priced from £650 for a 6-way board, with any additional ways or SPD requirements folded into that new board rather than fitted twice. This is discussed and agreed before any work starts, never discovered partway through.