Fuse board replacement across Sussex.

The day itself

How a board change actually runs.

1. 1. Pre-work testing. Ze, PFC and insulation resistance on every existing circuit, plus a check of the earthing arrangement and main bonding. This decides whether the board can simply be swapped.
2. 2. Bonding and earthing. 10 mm² main protective bonding to gas and water where missing or undersized; on a TT supply the electrode resistance is measured and improved if needed.
3. 3. Isolation. Supply isolated at the cutout, proved dead to GS38, locked off for the duration.
4. 4. Transfer. Circuits identified, re-terminated into the new board and labelled properly — no faded handwriting or "spare?" on the schedule.
5. 5. Dead and live testing. Continuity, insulation resistance, polarity, Zs and RCD/RCBO trip times recorded circuit by circuit.
6. 6. Certification. Electrical Installation Certificate with the full schedule of test results, plus the Part P building regulations certificate via NAPIT.

Background reading: AFDDs explained, surge protection and earthing systems.

Fuse board FAQs

Consumer unit questions from Sussex customers.

How long does a consumer unit replacement take?

A straightforward domestic changeover is a full day: isolate, transfer circuits, test every circuit dead and live, then certificate. If circuits fail insulation resistance once they are off the old board, the fault has to be traced before the new board can be energised — which is why Paul never books two boards in one day.

Will the power be off all day?

Expect the supply off for most of the working day. Paul can leave a temporary socket circuit live for a fridge or freezer in most jobs. Tell him at quoting stage if there is medical equipment, a home office deadline or a tenant working from home.

Do I have to have RCBOs rather than a dual-RCD board?

Dual-RCD boards are still permitted, but one earth fault takes out half the house, including the freezer and the boiler. Individual RCBOs isolate the faulty circuit only, and they make fault finding dramatically quicker later. On almost every replacement they are worth the modest extra cost.

Do I need AFDDs and a surge protection device?

Under BS 7671:2018+A2:2022 AFDDs are required on socket circuits up to 32 A in HMOs, purpose-built flats, student accommodation and care homes, and are recommended elsewhere. SPDs are required unless a documented risk assessment shows otherwise — in practice that means most boards get one fitted. Where the building has a structural lightning protection system (LPS to BS EN 62305), a risk assessment by a qualified lightning protection engineer is required before any wiring alterations or new circuits, to advise what surge protection must be installed.

Does a new board mean my whole house needs rewiring?

Rarely. A new board is only safe if the existing wiring passes insulation resistance and has a satisfactory CPC on every circuit. Older lighting circuits with no earth, or perished rubber cable, must be dealt with first — Paul tests before quoting so this is known up front, not discovered mid-job.

Is the work notified to building control?

Yes. A consumer unit replacement is notifiable work under Part P in England. As a NAPIT approved contractor Paul self-certifies the work and the building regulations compliance certificate is issued to you, with the installation certificate, after completion.