What Are the Different Types of Fuse Board? A Dartford Electrician’s Guide
Your fuse board sits quietly in a cupboard or under the stairs, and most people never think about it until something trips or an electrician tells them it needs replacing. But the type of fuse board in your home says a lot about the age and safety of your electrical installation. Older boards provide far less protection than modern units, and understanding the differences helps you make an informed decision if an upgrade is recommended.
This guide walks through the main types of fuse board you’ll find in homes across Dartford, from the oldest designs still in use to the latest consumer units. We’ll explain how each one works, what protection it offers, and how to tell which type is installed in your property.
Rewirable Fuse Boards
If your Dartford home was built before the 1960s and the electrics haven’t been fully updated, there’s a reasonable chance you still have a rewirable fuse board. These are the oldest type still found in occupied properties, and they’re easy to identify. The board has a row of individual fuse holders, each containing a piece of fuse wire stretched between two screws. When a circuit overloads or a fault occurs, the wire melts and breaks the circuit.
The problem with rewirable fuse boards is that they offer only basic overload protection and nothing else. There’s no protection against earth faults, no RCD to detect current leaking to earth through a person or faulty appliance, and no ability to detect the kind of small but dangerous faults that cause electrical fires. The fuse wire itself can also be replaced with the wrong rating — a common issue where previous owners have fitted thicker wire to stop a fuse blowing repeatedly, which defeats the purpose of the protection entirely and creates a serious fire risk.
If your home in Dartford still has a rewirable fuse board, it almost certainly predates current wiring regulations by several decades. The board itself may still function in the sense that it distributes power to your circuits, but the level of protection it provides falls far below what a modern installation requires. An EICR on a property with a rewirable board will almost always flag the lack of RCD protection as a C2 defect, meaning the installation is potentially dangerous and remedial action is needed.
Cartridge Fuse Boards
Cartridge fuse boards were a step forward from rewirable boards and were common in homes built during the 1960s and 1970s. Instead of a piece of wire, each circuit is protected by a ceramic cartridge fuse that fits into a holder. When a fault occurs, the cartridge blows and needs replacing with a new one of the correct rating.
Cartridge fuses are more reliable than rewirable fuses because they can’t be tampered with in the same way — you either have the correct cartridge or you don’t. They also blow more accurately at their rated current, providing better overload protection. However, like rewirable boards, cartridge fuse boards don’t include RCD protection. They cannot detect earth faults or current leaking through a person, which means they offer no protection against electric shock in the way a modern board does.
Many properties across Dartford, particularly in areas like Wilmington, Hawley, and parts of Dartford Heath where housing stock from this era is common, still have cartridge fuse boards in service. They’re not as urgently concerning as rewirable boards, but they still fall well short of current safety standards and will typically attract C3 observations on an EICR, with the lack of RCD protection flagged as a C2 if no supplementary RCD protection exists elsewhere in the installation.
MCB Consumer Units Without RCD Protection
From the 1980s onwards, consumer units fitted with miniature circuit breakers became the standard. MCBs replaced fuses entirely — instead of a wire or cartridge that needs replacing after it blows, an MCB is a switch that trips when it detects an overload or short circuit. You simply reset it once the fault is resolved. This was a significant improvement in convenience and reliability.
However, early MCB consumer units didn’t include RCD protection as standard. They protect against overloads and short circuits but not against earth faults. This means they won’t trip if current leaks to earth through a faulty appliance, damaged cable, or a person touching a live conductor. A shower developing a fault that sends current through the water to whoever is standing under it, for example, wouldn’t necessarily trip an MCB — but it would trip an RCD almost instantly.
If your Dartford home was rewired or had a new consumer unit fitted in the 1980s or 1990s, this is likely the type you have. The board looks relatively modern compared to older fuse boxes, with a row of MCB switches instead of fuse holders. But if there’s no RCD — usually a wider switch or a separate unit — the protection is incomplete by today’s standards. Some homeowners had a standalone RCD added later, either protecting all circuits or just specific ones like the shower circuit, which improves the situation but doesn’t match the protection offered by a fully modern board.
Dual RCD Consumer Units
The dual RCD consumer unit became the standard installation from around 2008 onwards when the 17th Edition of the wiring regulations made RCD protection mandatory for most circuits. This is the type of board fitted in most new builds and rewires carried out in the last fifteen years or so.
A dual RCD board splits your circuits into two groups, each protected by its own RCD. Within each group, individual circuits are protected by MCBs as before. The RCDs monitor for earth faults and current imbalance, tripping within milliseconds if they detect current leaking where it shouldn’t. This provides life-saving protection against electric shock and significantly reduces the risk of electrical fires caused by earth faults.
The main limitation of a dual RCD board is that when one RCD trips, it takes out every circuit on its side of the board. If a fault on your kitchen circuit trips the RCD, you might also lose your living room sockets and some lighting circuits because they share the same RCD. This isn’t a safety issue — the protection works exactly as it should — but it can be inconvenient, particularly if you lose lighting and power to multiple rooms while you identify which circuit caused the trip.
For most Dartford homeowners, a dual RCD consumer unit provides excellent protection at a reasonable cost. It meets current regulations, offers comprehensive fault detection, and is significantly safer than any of the older board types described above.
RCBO Consumer Units
An RCBO consumer unit represents the highest standard of domestic electrical protection currently available. Instead of grouping circuits under shared RCDs, every individual circuit gets its own RCBO — a device that combines MCB and RCD protection in a single unit. Each circuit is independently protected against overloads, short circuits, and earth faults.
The practical advantage is that a fault on one circuit only affects that circuit. If your oven develops an earth fault, only the cooker circuit trips. Everything else in the house continues working normally. This makes fault diagnosis simpler too, because the tripped RCBO tells you immediately which circuit has the problem.
RCBO boards cost more than dual RCD units because each individual device is more expensive than a standard MCB, and you need one for every circuit. For a typical three bedroom home in Dartford with eight to ten circuits, the additional cost over a dual RCD board is usually in the region of £100 to £200 — a modest premium for significantly better convenience and circuit independence.
The amendment to the 18th Edition of the wiring regulations has moved towards making RCBO protection the preferred standard for new installations, and many electricians now fit RCBO boards as standard for all upgrades and rewires. If you’re having a new consumer unit fitted, it’s worth discussing the RCBO option with your electrician.
How Do You Know Which Board You Have?
The simplest way is to open the cover of your fuse board and look at what’s inside. If you see individual fuse holders with wire or ceramic cartridges, you have an older board that almost certainly needs upgrading. If you see a row of switches with one or two wider switches among them, you likely have either an MCB board with RCDs or a dual RCD consumer unit. If every switch on the board is the same width and each is labelled with both a circuit name and an amp rating, you probably have an RCBO board.
If you’re not sure, or if your board has a mix of old and newer components suggesting it’s been modified over the years, the best course of action is to have a qualified electrician take a look. Many Dartford properties, particularly those in the older parts of town around the High Street, Lowfield Street, and the surrounding Victorian and Edwardian streets, have electrical installations that have been added to and modified over decades. What started as a rewirable board may have had an RCD bolted on, additional circuits added, or a partial upgrade that leaves the installation in an inconsistent state.
When Should You Upgrade?
If your fuse board is a rewirable or cartridge type, an upgrade is strongly recommended regardless of the condition of the rest of your wiring. The absence of RCD protection is a genuine safety gap. If you have an MCB board without RCD protection, the same applies. If your dual RCD board is in good condition and your installation is sound, there’s no urgent need to upgrade to an RCBO board, though it’s worth considering if you’re having other electrical work done at the same time.
A fuse board upgrade is one of the most cost-effective safety improvements you can make to your Dartford home. It typically completes within a day, causes minimal disruption, and the difference in protection between an old board and a modern consumer unit is substantial. If you’re unsure about your fuse board or want advice on whether an upgrade is worthwhile, get in touch for an honest assessment from a qualified Dartford electrician.