Consumer Unit Upgrade — What to Expect on the Day

You've read the earlier posts. You understand what a consumer unit does, you know why yours needs upgrading, and your EICR has confirmed it. Now the question is: what actually happens on the day? This post removes every uncertainty.

Before the day: what we'll have agreed

Before I arrive, we'll have had a conversation about the job. I'll have visited or seen photos, confirmed the number of circuits, and fixed the price for the upgrade itself. You'll know what you're paying before work starts, that's non-negotiable for me. If I open the board and find something that changes the job, I stop and show you before I carry on. Think of it like a builder giving you a quote before laying a single brick: you wouldn't expect to find out the final cost at the end, and neither should you here.

Morning: arrival and isolation

I'll arrive with the new consumer unit and all the parts needed for the job. First thing I do is confirm which circuits you have and check the existing board in detail. I'll also run a quick check on the meter tails and main earth, these need to be in good condition before we proceed.

Then the supply comes off. The fridge and freezer will be fine for several hours, but I'll let you know if the job looks like it'll run longer than expected.

During: out with the old, in with the new

Removing the old board is usually straightforward. Each circuit cable is carefully disconnected, labelled, and set aside. The old board comes off the wall. I then fix the new board in position, these days they're typically metal-encased for fire resistance, and start reconnecting circuits one by one.

Every circuit gets connected to its own RCBO. Think of it like upgrading from a shared emergency exit to giving every room its own dedicated fire escape, if something goes wrong in one room, only that room's exit is affected, not everyone else's.

As I reconnect each circuit, I label it clearly. By the end of the job, every single switch in the board will be labelled: upstairs lights, kitchen sockets, cooker, shower, and so on. No more mysteries.

Testing: every circuit, every connection

Once everything is connected, the testing begins, the same process described in Part 5. Each circuit is tested individually before it's switched back on, and I record the results for every circuit. This is what goes into your certificate.

End of day: power on and paperwork

Once testing is complete and everything passes, power comes back on. I'll walk you through the new board, show you which switch controls which circuit, explain what to do if something trips, and point out anything worth knowing.

You'll leave the day with an Electrical Installation Certificate (EIC), the formal document that records the work done and the test results. It's what a solicitor will ask for if you ever sell the property. Keep it somewhere safe.

When it might run to a second day

Most domestic consumer unit upgrades are genuinely a one-day job. But some situations can run longer, and I'll tell you if that's likely before we start: very poor condition wiring needing remedial work, significant earthing and bonding upgrades, large properties with high circuit counts, or unexpected complications like a circuit that can't be traced.

I won't rush a job to get it done in one day if the second day would mean better work. But I also won't drag a straightforward job out. You'll know what to expect before I arrive.

That's the series

You've now read all six parts of Understanding Your Electrics. You know what's in your cupboard, why it trips, what the warning signs look like, what an EICR involves, and what a consumer unit upgrade looks like from start to finish. If something needs doing, you're now in a much better position to understand what that means and why.

If you'd like to discuss your installation, whether it's a quick question or you're ready to book, get in touch.

Frankie Sewell
NICEIC Approved Contractor • YRLA Recognised Service Provider • Bright Sparks of York