It stopped after a blackout or storm
Everything was fine, the power went out, and the lighting system did not come back with it. Work through this in order: the most common causes are things that failed to restart, not things that were destroyed.
A C-Bus network is designed to ride out power interruptions and come back on its own. When it does not, there is a short list of reasons, and they run from free to fix down to genuinely damaged. Take them in that order, because the free ones are common and the expensive one is not.
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.
Work down this list in order
- 1. Check the breakers. Open the hinged door of your switchboard and look for a breaker or RCD sitting out of line with its neighbours. Resetting one is a normal householder action. If it trips straight back, stop: that is a real electrical fault, and it needs an electrician. The panel behind the breakers stays on.
- 2. Check anything that plugs in. If a controller, touchscreen or PC runs on a plug pack, confirm the power point is switched on and the pack has a light. Surge boards commonly trip and stay off.
- 3. Look at the wall plates. Any backlight or indicator glow anywhere in the house, or total darkness on every plate?
- 4. Check the time. If the lights work but timers fire wrongly, the system clock lost time during the outage.
What did you find?
- A breaker or RCD had tripped, or trips straight backThe electrical supply is the problem. If it resets and holds, you may already be fixed. If it trips again, stop and call an electrician.
- Every plate in the house is darkThe network power supply has not come back. Surges kill these more often than they kill anything else, and it is a single replaceable module.
- Lights work, but timers and scenes now fire at wrong timesThe clock lost time. Nothing is damaged; the system simply does not know what hour it is.
- A touchscreen or PC never came back onThe controller took the hit. Whether that matters depends on how much of your system's behaviour lived inside it.
Why the power supply is the usual casualty
The network power supply sits between the mains and the low-voltage bus, which puts it directly in the path of anything nasty coming down the line. That position makes it the most exposed module in the system and the most common single failure after a storm. It is also, conveniently, one module on a rail rather than anything structural. Replacing one does not touch your wiring, your switches or your programming.
There is a longer treatment of this specific scenario in C-Bus not working after a power outage, including what to expect when the system comes back partially.