If your home was built or renovated between the late 1990s and the mid 2010s, there is a decent chance the light switches run on C-Bus. It was the premium Australian choice for two decades, and Canberra has some of the highest concentrations of it in the country.
Now the wall panels look dated, a dimmer channel has died, the programmer who set it up has retired, and you are being quoted eye-watering numbers to touch any of it. We get called into these homes every month. Here is the honest map of your options.
First, the good news
C-Bus is wired, and the wiring is the valuable part. Every switch position already has a bus cable behind it, and the load switching lives in the electrical board. That topology is exactly what modern wired systems want. Whatever you decide, the copper in your walls is an asset, not a liability.
Option 1: Keep it and integrate it
C-Bus still switches lights perfectly well. What it lacks is a modern brain: no decent app, no presence automation, no link to cameras, climate or voice.
The fix is to leave the C-Bus doing what it does and put Home Assistant in front of it. C-Bus talks to Home Assistant through a network interface, and from there your existing lighting joins everything modern: one app, scenes, sensors, cameras, climate, the lot.
Best when: the C-Bus hardware is healthy and you want modern control without touching the walls. Rough cost: low thousands, depending on what else you integrate at the same time. Trade-off: you are still running discontinued-era hardware underneath. Budget for the odd module failure.
Option 2: Extend it
If you are renovating one area, it is often cheaper to run the new rooms on modern hardware and bridge both systems under one controller than to buy legacy C-Bus modules for the extension. The old house stays C-Bus, the new wing runs current gear, and Home Assistant makes them feel like one system. We covered the general approach in bridging legacy systems with modern smart homes.
Best when: you are renovating or extending anyway. Trade-off: two generations of hardware to maintain until you eventually consolidate.
Option 3: Replace it
When modules are failing or you want wall controls that match a modern interior, replacement is on the table. Because C-Bus homes already have bus wiring and centralised switching, they convert unusually well: the same architecture suits KNX, and in many homes quality relay hardware can reuse the existing load wiring in the board. Which way to jump depends on the house, and the thinking mirrors our KNX vs Shelly comparison.
Best when: hardware is failing, or you are doing a full renovation. Rough cost: mid five figures for a whole home done properly, in line with the full-home tier in our cost guide. Trade-off: it is the big spend. The payoff is one modern system, no legacy parts bin, and hardware with decades of support ahead of it.
What we would do in your house
It genuinely depends on the state of the hardware, and that is a one-visit diagnosis. As a rule of thumb:
- Healthy C-Bus, dated experience: integrate (Option 1). Biggest result per dollar.
- Renovating anyway: extend and bridge (Option 2), consolidate later.
- Failing modules, full reno, or you are done with legacy gear: replace (Option 3).
One warning: be careful with anyone whose answer is "rip it all out" before they have opened your switchboard. The wiring in a C-Bus home is half the cost of a new system already paid for. Anyone who does not see that value is not looking.
We assess C-Bus homes across Canberra and Sydney. Book a free consultation and we will open the board, test what is alive and give you the three options priced for your actual house.