Signs to look for
Most of these can be spotted without opening anything. Do not remove the cover yourself.
- Rewirable fuses (a fuse wire in a ceramic or plastic carrier) or cartridge fuses instead of switches.
- No residual current device (RCD) — the switch with a test button that cuts the power if current leaks to earth.
- Scorch marks, a burning smell, buzzing or crackling, or a casing that is warm to the touch.
- Switches that trip repeatedly with no obvious faulty appliance.
- A wooden backboard, a cracked case, or a unit that has been added to piecemeal over the years.
- An EICR that records a C1 or C2 against the consumer unit.
Plastic consumer units
Since January 2016 the wiring regulations (BS 7671) have required new consumer units in homes to have a non-combustible enclosure, which in practice usually means metal. The rule applies to new installations. An existing plastic unit is not automatically unsafe, and an inspection will say whether it needs replacing.
Who can replace it
Replacing a consumer unit is notifiable under Part P in England. A registered electrician can self-certify the work and should give you an Electrical Installation Certificate and a Building Regulations compliance certificate. Keep both: a buyer's conveyancer or a future inspector will ask for them.