Calculator

Consumer Unit Replacement Cost Calculator

Estimate the cost of replacing your fuse box or consumer unit. Compare RCD and RCBO options based on your number of circuits and location.

How to Use

Identify your current consumer unit type — check if it has rewirable fuses, MCBs with an RCD, or a split-load setup.

Count the number of circuits (fuses or MCBs) in your current unit.

Choose whether you want a dual RCD board (cheaper, standard protection) or a full RCBO board (each circuit individually protected).

Select your region for location-adjusted pricing.

The estimate includes Part P certification when done by a registered electrician.

About This Calculator

This consumer unit cost calculator helps homeowners estimate the cost of upgrading or replacing their fuse box (consumer unit). Whether you have an old rewirable fuse box or a dated RCD board, enter your current setup, number of circuits, upgrade preference, and region to get a realistic cost estimate. All consumer unit replacements are notifiable under Part P and require certification.

Frequently Asked Questions

How much does it cost to replace a consumer unit?

A consumer unit replacement typically costs £500-£800 for a dual RCD board and £750-£1,200 for a full RCBO board. London prices are 20-30% higher. The price includes the consumer unit, labour, testing, and Part P certification. Old fuse boxes with rewirable fuses may cost more to replace if the existing wiring needs attention.

What is the difference between RCD and RCBO?

A dual RCD board splits your circuits into two groups, each protected by an RCD. If one RCD trips, you lose half your circuits. An RCBO board gives each circuit its own individual protection — if one trips, only that circuit is affected. RCBOs cost more but offer better protection and less inconvenience.

Do I need a Part P certificate?

Yes — replacing a consumer unit is notifiable work under Part P of the Building Regulations. If a registered electrician (NICEIC, NAPIT, etc.) does the work, they self-certify and the certificate is included. If an unregistered electrician does the work, you must apply to Building Control separately, which costs £200-£400 extra.

How long does a consumer unit replacement take?

A straightforward consumer unit swap typically takes 4-6 hours (half a day to a full day). If additional work is needed — such as upgrading earthing, replacing the meter tails, or addressing issues found during testing — it may take a full day or more.

Should I upgrade to an RCBO board?

If budget allows, yes. The extra cost (typically £200-£400 more) is worth it for the convenience and safety. With a dual RCD board, a fault on one circuit can trip the RCD and cut power to several other circuits — including freezers, security systems, and medical equipment. RCBOs prevent this.

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