The distribution board is the heart of every installation. Whether you're building a new board or fault-finding an old one, the fundamentals don't change. Here's a practical refresher aligned to SANS 10142-1.
Anatomy of a board
- Main switch / isolator — disconnects the whole board.
- Earth-leakage unit (RCD) — protects against earth faults; group circuits sensibly beneath it.
- Circuit breakers (MCBs) — one per circuit, correctly rated to the cable and load.
- Busbars, neutral and earth bars — clean, torqued terminations, no doubling-up where it isn't allowed.
Protection hierarchy
Selectivity matters: a fault on one circuit should trip that circuit's breaker, not the main. Size breakers to protect the cable first and the load second, and make sure the earth-leakage covers the circuits it's required to without nuisance-tripping the whole house.
Labelling and neatness
A clearly labelled, tidily wired board isn't vanity — it's a safety and compliance requirement, and it's the first thing an inspector notices. Every circuit identified, conductors dressed, correct colours throughout.
Common CoC failures
- Under-rated or missing earth-leakage protection.
- Breakers that don't match cable size.
- Loose terminations and un-torqued busbars.
- Missing or illegible circuit labelling.
- Mixed manufacturers on a single din rail where it compromises fit or rating.
Stock the board right
Ampworks carries CHINT circuit breakers, earth-leakage units, isolators and terminals and accessories — trade-priced and in stock. Open a trade account for volume pricing on board builds.