The clock or the schedules are wrong
The correct things happen, at the wrong times. Outside lights at three in the afternoon, a goodnight scene at lunch, or everything running exactly an hour out. No part has failed here.
The system clock has lost time or was never corrected, or a schedule that nobody remembers is still faithfully running. Both are configuration, not hardware.
Where the time actually comes from
Something on your network keeps the clock and tells everything else what time it is. Depending on how your system was built that could be a dedicated unit, a touchscreen, or a controller. Whichever it is, it is a small piece of hardware with a battery-backed clock, and after fifteen or twenty years that battery is usually flat. A flat clock battery means the time survives while the power is on and is lost the moment it goes out.
That single fact explains the most common version of this fault: everything worked, there was a blackout, and now the timers are wrong. The system came back and simply did not know when it was.
- An hour out, twice a year
- Daylight saving. Some systems were never set up to handle the change and need it done manually, which nobody has been doing since the installer left.
- Wrong since the last blackout
- A flat clock battery. Cheap to fix, and worth fixing properly rather than resetting the time each outage.
- Drifting slowly over months
- Normal clock drift in a system with nothing correcting it. Some setups can be synchronised so this stops happening.
- Sunset timings sliding through the year
- That is an astronomical timer working correctly. It tracks sunset by design, so it moves with the seasons and looks wrong if you expected a fixed hour.
Nothing on this page asks you to take anything apart. Every check here is done by looking, or by pressing buttons that are already on the outside of a wall plate. Opening the hinged door of your switchboard to see the breakers is normal and fine. Removing the panel behind them is not, and neither is unscrewing a wall plate or lifting the cover off an enclosure.
In Australia it is illegal to work on fixed wiring without an electrical licence, and the reason is not paperwork: the terminals behind a C-Bus wall plate can be sitting at mains voltage. Anything past the faceplate is a job for a licensed electrician, ideally one with C-Bus accreditation.
Schedules nobody remembers
The other half of this verdict. C-Bus systems commissioned in the 2000s often had schedules built in for a household that no longer lives there: garden lighting on a particular evening pattern, a holiday mode, a pool pump interlock, a lamp that comes on because a child used to come home at that hour. They keep running, invisibly, and a new owner experiences them as the house behaving strangely.
Nothing about that is broken. It is a house still following instructions from a decade ago. Fixing it means someone connecting, reading the schedule list, and deleting what nobody wants any more. That is usually a short job and often the most satisfying one, because it removes several small annoyances at once.
What to do before you call
Keep a log for a few days: what happened, and exactly when. If the events are at consistent times you are looking at schedules and the log tells the integrator which ones. If the times slide steadily, you are looking at the clock. If they track sunset, it is an astronomical timer. That distinction takes you three days of noticing and saves paying someone to observe your house.
When it is not the clock at all
If the timing is right but the behaviour is wrong, that is programming rather than time: see the programming verdict. If it started when a computer or touchscreen died, the schedules may have lived on that machine, which is covered in the dead controller page.
Lights running to somebody else's timetable?
Send the log of what happens and when. Clearing out inherited schedules and getting the clock holding time is usually one short visit, and it is often the fix that makes a house feel like yours.