Replacing a fuse board is one of the most common jobs electricians do, and one of the most disruptive for the household, simply because everything goes off while the board is changed. Knowing roughly how the day runs helps you plan work, meals and anything that must stay cold. It also helps you understand why some jobs take longer than the headline figure.
The short answer
Plan on a working day. The old board comes out, the new consumer unit goes in, each circuit is reconnected, and then every circuit is tested before power is restored for good. The testing is not optional and it is not quick, because it is what proves the new board is protecting each circuit properly.
How the day usually runs
Testing before the change is important. It shows up faults that the old board was tolerating but a modern board with residual current protection will not, so there are fewer surprises at the end of the day.
- Arrival, a check of the existing board and a quick walk round
- Tests on the existing circuits before anything is disconnected
- Power off, old board removed, new board fixed in place
- Circuits reconnected and labelled one by one
- Earthing and bonding checked and improved where needed
- Full testing, then power on and a final functional check
What can make it take longer
The most common delay is a fault found on an existing circuit. A circuit with a leak to earth may have been fine on an old fuse board but will trip modern protection straight away. It has to be found and fixed, or left disconnected until it can be, before the job is complete.
- Faults on existing circuits revealed by testing
- Main bonding to gas or water missing or undersized
- Moving the board to a new position
- A large number of circuits or a split load arrangement
- Tails or the main switch needing attention from the supplier side
Living with the power off
Keep fridge and freezer doors shut and they will usually hold temperature for the day. Charge phones and laptops the night before. If anyone works from home, plan to work elsewhere or offline. If anyone in the house depends on powered medical equipment, say so when booking so the day can be planned around it.
Preparing for the visit
Clear the area around the board and make sure there is safe access to it. Let the electrician know about any circuits that already misbehave, such as an outside socket that trips in the rain. Having the loft and under-stairs cupboard accessible helps if cables need tracing.
Paperwork at the end
A replacement consumer unit is notifiable work, so you should receive an electrical installation certificate with test results, and the job should be notified to building control. Keep both documents. They matter when you sell and they help any future electrician.
Is a day enough for your house?
A day covers most typical homes. Larger properties, boards in awkward positions, or jobs that include other work such as surge protection or new circuits can run longer. A written quote after a proper look at your board should say how long the electrician expects it to take, so you can plan with confidence.
Common questions
- How long is the power off?
- For most of the working day on a standard domestic change. The electrician will agree a start time with you.
- Can I stay in the house?
- Yes. Most people stay home. You will just be without power for most of the day.
- Why do old circuits sometimes trip the new board?
- Modern residual current protection detects small leaks to earth that old fuses ignored. Those faults need fixing.
- Will I get a certificate?
- Yes. A replacement consumer unit gets an electrical installation certificate and is notified to building control.
Thinking about a new consumer unit? Get a free written quote that sets out the day clearly.
Related guides
- What Affects the Cost of a Consumer Unit UpgradeTwo identical-looking boards can be very different jobs once the cover comes off.
- Do I Actually Need a Consumer Unit Upgrade?An old board is not automatically a dangerous board, but some of them genuinely are.
- RCD vs RCBO: What the Difference Means at HomeThe difference is not protection quality — it is how much of your house goes dark when something leaks.