KNX Lighting Control: Matching the Controller to the Job

A hotel corridor retrofit lands on your desk with forty fluorescent battens going to LED, all on one KNX bus, and the client wants scene control from a central panel. The lighting designer specs "a KNX lighting controller" and leaves it at that. Which one, with how many outputs, is the part nobody wrote down.

Schnap carries several controllers under Other BUS Automation, and they aren't interchangeable. Picking the wrong one means a second order mid-job or a controller running well under its capacity.

What Each Controller Actually Switches

The KNX Lighting Controller gives you 8 outputs rated 8A per channel, on 4 DIN modules — straightforward on/off or relay-driven lighting circuits, one controller per zone of that size. The KNX Modular Controller steps up to 500VA per output across its DIN modules, built for larger or mixed loads rather than simple switching.

Once ballasts come into it — DALI-dimmed fluorescent or LED drivers rather than plain on/off circuits — the job usually calls for a power room controller instead. The 8-in/10-out Legrand unit takes 8 digital inputs and drives 10 outputs across 8 DIN modules, and it's rated for up to 64 ballasts. That number is what decides whether one controller covers the floor or whether you're splitting the job across two.

Working Out Which One Covers the Job

Count ballasts, not fittings — some fittings run two ballasts. For the corridor example above, forty fittings at one ballast each sits comfortably under the 8-in/10-out controller's 64-ballast ceiling, with headroom for the client adding fittings later. Cross that number and you're either adding a second controller or stepping up to the 16-in/16-out unit, which gives you more inputs and outputs to work with on one DIN rail rather than splitting the circuit across two devices.

Flicker complaints after a retrofit usually trace back to a controller under-sized for the dimming curve it's being asked to run, not a faulty driver — worth ruling out before you start swapping LED drivers one by one, a problem covered in more detail in our guide to fixing LED dimmer flicker.

If the job also calls for occupancy-based triggering rather than a fixed scene, that's usually a sensor decision on top of the controller choice — see our breakdown of matching DALI occupancy sensor IP ratings to the space.

None of this decides itself without the wall side of the system. Choosing the right KNX switches to trigger these outputs is its own decision, covered separately — the controller and the switch plate need to agree on scenes before either gets ordered.

Frequently Asked Questions

Installation & Compliance

Does a KNX lighting controller need to be installed by a licensed electrician?

Yes. These controllers sit inside switchboards and connect to mains-voltage circuits, so installation and commissioning in Australia should be carried out by a licensed electrician, typically one with KNX system training, in line with AS/NZS 3000.

Can I mix controller types on the same KNX line?

Generally yes — KNX is designed around multiple device types sharing one bus. The practical limit is usually bus power and addressing capacity rather than mixing controller models.

Capacity & Compatibility

How many ballasts can one KNX power room controller run?

The 8-in/10-out Legrand controller is rated for up to 64 ballasts. For higher ballast counts on one device, the 16-in/16-out power room controller gives more inputs and outputs to work with.

Does a KNX lighting controller dim lights, or only switch them on and off?

The 8-output lighting controller switches rather than dims. Dimming DALI-ballasted fittings needs a controller built for that output, like the power room controllers above or a dedicated DALI controller for simpler single-line jobs.

What's the difference between the lighting controller and the modular controller?

The lighting controller is built for straightforward 8A switched circuits. The modular controller handles higher loads per output (500VA), making it the better fit when the circuit isn't simple on/off lighting.

Shop KNX Lighting Control at Schnap

All controllers below ship with trade pricing and same-day dispatch from our Kingsgrove NSW warehouse.

Lighting & Modular Controllers

• KNX Lighting Controller, 8 Outputs 8A per Channel
• KNX Modular Controller, 500VA per DIN Module

Power Room Controllers (Ballast Control)

• KNX Power Room Controller, 8 In / 10 Out, up to 64 Ballasts
• KNX Power Room Controller, 16 In / 16 Out

Browse the full knx lighting control range at Schnap.