Consumer Unit Upgrades: Why Your Old Fuse Box Could Be a Fire Risk
If your {location} home still has a rewirable fuse box — the type with porcelain fuse holders and thin wire — it may be decades out of date and lacking the safety features that modern consumer units provide. Here's why upgrading matters and what's involved.
What Is a Consumer Unit?
A consumer unit (CU) is the modern equivalent of a fuse box. It's the metal or plastic enclosure where your electricity supply is distributed to individual circuits around your home. Each circuit is protected by a circuit breaker that trips automatically if a fault is detected.
Why Old Fuse Boxes Are Dangerous
Older fuse boxes, particularly those installed before the 1990s, typically lack two critical safety features:
- RCDs (Residual Current Devices) — these detect earth faults and trip within milliseconds, preventing electric shocks and reducing fire risk. Old rewirable fuses offer no earth fault protection
- MCBs (Miniature Circuit Breakers) — these replace fuse wire and trip instantly during an overload. Rewirable fuses can take seconds to blow, during which time overheated cables can start a fire inside your walls
Additionally, many old fuse boxes are housed in plastic enclosures. Since 2016, UK regulations (Amendment 3 to BS 7671) require all new or replacement consumer units in domestic properties to be made from non-combustible materials — typically metal — to contain any fire that might start within the unit.
Signs You Need an Upgrade
- Your fuse box uses rewirable fuse wire rather than switches
- The enclosure is made of brown or white plastic
- You don't have an RCD (no "test" button anywhere on the board)
- Fuses keep blowing without obvious cause
- You're having an extension, loft conversion, or kitchen refit (building regulations will likely require an upgrade)
- Your home insurance requires a modern consumer unit
What Does an Upgrade Involve?
A qualified electrician will:
- Isolate the electricity supply (your power will be off for 4–8 hours)
- Remove the old fuse box
- Install a new metal consumer unit with RCDs and MCBs (or RCBOs for individual circuit protection)
- Test every circuit in the property
- Issue an Electrical Installation Certificate (EIC) — this is a legal requirement
- Notify Building Control through a Part P self-certification scheme (NICEIC, NAPIT, or similar)
How Much Does It Cost?
In {location}, a consumer unit upgrade typically costs between £350 and £700 depending on the number of circuits, the condition of existing wiring, and whether any additional work is needed (such as upgrading earthing and bonding). This is a regulated job that must be carried out by a qualified electrician registered with a competent person scheme such as NICEIC, NAPIT, or ELECSA.
Is It Worth It?
Absolutely. A consumer unit upgrade is one of the most cost-effective safety improvements you can make to your home. It protects against electric shocks, reduces fire risk, satisfies building regulations and insurance requirements, and gives you the peace of mind that your electrical protection actually works. If your fuse box is more than 20 years old, speak to a qualified electrician in {location} about an upgrade.