What to check first
Go to your DB box first, before calling anyone. Look at whether the main switch, or one of the smaller switches beside it, has flipped to the off or middle position rather than staying firmly up.
Check whether a neighbour on the same floor or the same stack still has power. The third cause is a supply-side fault affecting more than your own flat, such as a fault on the building's shared supply or a wider outage, which you can usually rule out by checking whether a neighbour on the same floor or stack still has power.
Try resetting the switch once. If it stays on, think about what you were using right before it tripped — an appliance you had just switched on is a strong clue to what caused it. If it trips again immediately, stop and do not keep resetting it.
The likely causes, in order
A tripped main switch from a faulty appliance or overload (most common). The most likely cause is the main switch at your DB box has tripped, usually from a single faulty appliance, an overloaded circuit, or a genuine short somewhere in the wiring, and resetting it without finding the cause often trips it straight back off. Safe check: unplug what you were using when it tripped, then reset the switch once and see if it holds.
An earth-leakage or RCD trip (second most common). The second cause is an earth-leakage or residual-current trip, a safety device that cuts power the moment it detects current escaping where it should not, commonly set off by a wet appliance, a water heater fault, or a damaged cable rather than the DB box itself being broken. Safe check: think about whether water was involved recently, such as a wet bathroom appliance or a leak near a socket.
A wider supply fault (third most common). The third cause is a supply-side fault affecting more than your own flat, such as a fault on the building's shared supply or a wider outage, which you can usually rule out by checking whether a neighbour on the same floor or stack still has power. Safe check: if neighbours also have no power, this is not your DB box, and an electrician alone cannot fix a supply-side fault.
When to call, and who
Call an electrician once your own DB box has been checked and either the switch will not stay reset, or you cannot identify what tripped it safely yourself. Tell them what you were using when the power went, and whether it tripped once or keeps re-tripping.
Opening a DB box, tracing a fault, or repairing home wiring in Singapore must be done by a Licensed Electrical Worker (LEW), the licence EMA regulates. Do not have an unlicensed handyman open the DB box, even to reset a switch that keeps tripping.
Stop resetting the main switch repeatedly if it trips again immediately. A switch that will not stay on is telling you there is an active fault, and repeatedly forcing it back on risks worse damage or a fire rather than fixing anything.
What it costs
Ask for a firm quote for the actual job once diagnosed.
When you ask, describe exactly what you found at the DB box: which switch tripped, whether it re-trips immediately, and what you were using at the time. A provider who knows it is a re-tripping earth-leakage switch, not a simple overload, can quote closer to the real job before arriving.
Ask whether the quote is a flat callout fee, and whether any parts, such as a replacement breaker, are quoted separately.
Who to call, and how to judge them
Opening a DB box, tracing a fault, or repairing home wiring in Singapore must be done by a Licensed Electrical Worker (LEW), the licence EMA regulates. Ask specifically whether the technician attending holds a current LEW licence, since that is the credential that matters for this work, not the business registration alone.
An electrician checking total power loss should identify which switch at the DB box actually tripped, then isolate circuits one at a time to find the faulty one before restoring power to the rest of the flat, rather than resetting everything at once.
Frequently asked questions
Why did my whole flat lose power at once?
No power at all means every light and socket in the flat has stopped working at once, which almost always points to the main switch or an earth-leakage trip at your own DB box rather than a fault with the electricity supply to the whole building.
Sources
- EMA, "Electricians Licence" (fetched 15 Sep 2026)
- EMA, "Engaging Licensed Workers" (fetched 15 Sep 2026)
- gov.sg, Singapore Government homepage (fetched 15 Sep 2026)
Compare electricians and confirm the attending technician holds a current LEW licence.
