Distribution boards
Sub-mains, three-phase boards, busbars and balancing.
Three-phase distribution board badly unbalanced
One phase of a three-phase board runs much hotter / higher current than the others — nuisance tripping on that phase, a hot neutral, or a warm phase conductor at the board.
Sub-main keeps tripping the main board
A sub-board's incoming protective device (or the main feeding it) trips — taking out everything downstream — and you need to tell overload from a fault on the sub-main or sub-board.
Busbar or board connection running hot
A busbar joint, incomer, or board connection runs hot / discoloured — a high-energy fire-risk fault on a distribution board that must be addressed quickly.
Main switch / incomer not making on all phases
A board's main switch or incomer isn't passing all phases — downstream gets partial supply (single-phasing) or nothing — pointing at the switch contacts or its terminations.
Distribution board circuits mislabelled / wrong breaker isolates wrong circuit
Switching off a labelled breaker doesn't isolate the expected circuit (or isolates the wrong one) — a schedule/labelling problem that's a real safety hazard for anyone relying on it.
Three-phase supply voltage high, low, or unbalanced
Measured supply voltages are out of the expected range or unbalanced between phases — causing equipment trips, poor performance, or protection operating across the board.
Surge protection device (SPD) showing a fault / end of life
A board-mounted surge protective device shows a fault indicator (window changed colour / flag) — it has likely reached end of life after absorbing surges and no longer protects.
Large motor start trips the distribution board
Starting a large three-phase motor (lift, pump, compressor, aircon) trips the board feeding it or dips the supply — an inrush/coordination issue rather than a running fault.