Consumer unit upgrade cost, and what changes it

What is in the price

A consumer unit replacement is a day's skilled work plus a board. It covers isolating the supply, removing the old unit, mounting the new one, transferring every circuit with each conductor identified and tested as it goes back, checking and upgrading bonding, full testing of the whole installation, labelling, certification and notification.

The part people underestimate is the testing. A new board is certified work, and the certificate covers the circuits connected to it. Every circuit has to be tested and pass before it can be signed off, which is why a board change is really an inspection with a board fitted in the middle of it.

• Labour for a full working day in most properties
• The board itself, priced by type and number of ways
• Full testing of every existing circuit
• Certification and building regulations notification

Board type and circuit count

A split load board with one or two RCDs is the cheaper option. An RCBO board, with individual protection per circuit, costs more but means a fault on one circuit does not take out the fridge, the router and the alarm. For most households the RCBO board is worth the difference, particularly where there are tenants, freezers or home working.

Circuit count drives both board size and labour. A house with six circuits is a shorter job than one with twelve, and properties that have accumulated an outside supply, a garage, a shower and an EV charger over the years often need a larger board than the one they are replacing. Surge protection is an increasingly common addition and adds modestly to the cost.

Bonding, earthing and supply side work

Main protective bonding to the incoming gas and water services must be present and correctly sized. In older properties it is frequently missing, undersized or connected in the wrong place, and it cannot be left that way once a new board is certified. Running new bonding conductors from the board to the services can add meaningful cost, particularly where the gas meter is at the front and the board is at the back.

Occasionally the meter tails need replacing, or the earthing arrangement needs verification with the network operator. Those are not upsells: they are conditions that have to be met before a certificate can be issued honestly.

• Main bonding to gas and water, correctly sized and terminated
• Meter tails replacement where undersized or damaged
• Earthing arrangement verified before the board is specified
• Any supply side work is the network operator's, not the electrician's

The remedial work question

Here is the honest bit. A modern board provides RCD protection an older board never did, and that protection detects faults that were previously invisible. A damp outside light, a deteriorating shower element or an old cooker with degraded insulation will trip a new RCD immediately, and testing finds these before the board goes on.

A good quote flags this risk up front and prices the survey properly. A cheap quote leaves it out and it reappears as a variation on the day. Ask every quote directly: what happens if a circuit fails insulation resistance testing, and how will that be priced. The answer tells you a lot about the firm.

Comparing quotes and what you should receive

Ask each quote for the board specification, whether it is split load or RCBO, whether surge protection is included, whether bonding upgrades are included or excluded, and how remedial work is handled. Then compare. A quote that excludes bonding and remedials is not cheaper, it is less complete.

At the end you should have a board with correct protection for the circuits present, properly labelled ways, upgraded bonding where it was needed, an Electrical Installation Certificate with a full schedule of test results, and the building regulations notification. That certificate is what matters at sale, at insurance renewal and to the next electrician who opens the board.