Many consumer units installed in the last two decades are split-load: two RCDs, each protecting roughly half the circuits. When one RCD trips, you lose that half — often upstairs lighting and downstairs sockets, or some similarly odd-looking pairing that follows the board rather than the building.
First, look at the board
Open the flap and look for a switch sitting in the middle or down position. Reset it firmly. If it holds, note the time and what was running — that context matters. If it drops again immediately, follow a circuit-by-circuit isolation.
If nothing on the board has tripped
Then you may be looking at a supply issue — a failed cut-out fuse or a network fault — or a loose connection at the main switch. Neither is a DIY job. A total loss on one phase of the supply is for the network operator; a board-side connection is ours.
The longer-term fix
Split-load boards were a step forward, but they still let one fault disable a lot of the house. Replacing with RCBOs per circuit means a leak on the garden lighting no longer takes the fridge freezer with it. We quote both options so you can decide.
Common questions
- Are my neighbours affected?
- Worth checking. If the street is out, it is a network fault and not something inside your property.
- Can I run an extension from the working half?
- As a very short-term measure for a fridge, yes, but do not run heaters or high loads that way.
- Is a board upgrade notifiable?
- Yes, a consumer unit replacement is notifiable work and comes with a full installation certificate.
- How long does a board change take?
- A typical domestic change is a single day, with the supply off for most of it.
Photograph your consumer unit and send it over — we can usually tell you the board type and likely options before visiting.
Related guides
- RCD Will Not Reset: How to Find the CircuitAn RCD that will not stay in is holding back a live earth-leakage fault somewhere on its side of the board.
- What Affects the Cost of a Consumer Unit UpgradeTwo identical-looking boards can be very different jobs once the cover comes off.
- Metal and Plastic Consumer Units ComparedThe move to non-combustible enclosures was a response to real failures, not a fashion.