Consumer Unit Upgrade Cost Guide: Fuse Box vs Modern Board

"Fuse box" and "consumer unit" get used interchangeably, but if yours is genuinely an old fuse box — with fuse wire or fuse cartridges rather than switches — it's worth understanding exactly what upgrading it involves, and what it actually costs.

What you're actually paying for

A standard dual-RCD consumer unit typically runs £500–£800 all in; stepping up to a full RCBO board — where every circuit gets its own individual protection rather than sharing an RCD between several — is usually £800–£1,200. The higher spec isn't just an upsell: individual RCBO protection means a fault on one circuit doesn't knock out every other circuit sharing that RCD.

• Removal and safe disposal of the old fuse box or consumer unit
• Supply and installation of the new unit
• Testing of every circuit it feeds
• An Electrical Installation Certificate
• Part P building regulations notification

What can add to the cost

A few things commonly sit outside the base price and are worth asking about upfront: earth bonding upgrades (often £150–£300 if your property's earthing needs updating to match the new board), minor plaster repair around the unit if it's being relocated, and remedial work if testing uncovers a fault on an existing circuit.

Is it actually a legal requirement?

No — you're not legally required to replace a working fuse box. But older units generally lack RCD protection, which is what actually cuts power fast enough to prevent a serious electric shock. If yours is flagged during an EICR, or you're adding a new heavy load like an EV charger, that's usually the point it becomes worth doing rather than putting off.

Why you can't do this yourself

Consumer unit replacement is notifiable work under Part P of the Building Regulations, and it needs to be carried out and certified by a qualified, registered electrician — not something to attempt as a weekend project, regardless of how it looks online.