In 40 seconds
Replacing a consumer unit (the modern name for a fuse board or fuse box) in the UK usually costs roughly £350–£1,200, commonly around £500–£800 for a board using RCDs and about £800–£1,200 for a full RCBO board, including the unit, labour, testing and certification. The work is notifiable under Part P of the Building Regulations in England and Wales, so it must be done by a registered electrician who self-certifies (or pre-notified to building control), and it comes with an Electrical Installation Certificate (EIC) and a Building Regulations compliance certificate. A straightforward job usually takes around 4–8 hours, with the power off for most of that. The honest answer is always a range, because it depends on your number of circuits, board type and the condition of your existing wiring.
Most consumer unit guidance is published by the firms fitting the boards, so the numbers tend to be optimistic and the rules glossed over. The pages below give honest cost ranges, explain how a modern consumer unit differs from an old fuse box, set out the signs yours needs replacing, and cover the Part P rules and timescales — before you take a single quote.