Distribution boards quietly become the weakest part of an older installation. The cables and accessories around them get replaced over the years; the DB itself does not, until something forces the issue. The right time to think about a DB upgrade is before that forcing event.
Five signs the DB is the next thing to upgrade
- No RCCB / RCD protection — only single-pole MCBs, dating the DB to before residual-current protection became standard
- Recurring nuisance trips that move around — the main RCCB drops out for no clear single cause
- Visible heat marks or discolouration on the DB door, busbar or specific MCB
- Loose feel when an MCB is switched — the mechanism wears out over years of use
- Circuit count outgrown — owners adding sockets and lights for a decade with no spare ways left
What "RCBO" changes in practice
In a one-RCCB-for-everything DB, any earth leakage anywhere in the unit drops out the whole flat. In an RCBO-per-circuit DB, only the affected circuit drops out. The freezer keeps running while the bathroom heater is diagnosed. The cost difference is small. The convenience and safety difference is large.
What a one-day DB upgrade looks like
- Isolation at the incoming, with the supply licensee informed where required
- Existing DB removed; new enclosure mounted
- New incoming isolator, main earth conductor confirmed and resized if needed
- Per-circuit RCBOs installed, sized to each circuit's load
- Every circuit tested — insulation resistance, polarity, earth continuity — and labelled
- Energisation, RCD test button verified on every device, circuit schedule taped inside the door
This is licensed work. The LEW on the job is the worker who signs the test record. Check the licence number on the EMA ELISE Licensed Electrical Worker directory before the day of works.
Labelling is half the value
A correctly labelled DB pays for itself the first time someone needs to isolate one circuit without dropping the whole unit. The schedule lives inside the door — paper, laminated, and updated every time a circuit changes.
