Choosing a dimming protocol is a commercial decision as much as a technical one: it fixes your wiring cost, your control vendor, your spare-parts strategy and how easily the building can be re-zoned in five years. This guide compares the four protocols we are asked to build most often, with the wiring and failure modes behind each.
The four protocols at a glance
| 0/1-10V | DALI-2 | TRIAC (phase-cut) | Casambi (BLE mesh) | |
|---|---|---|---|---|
| Signal type | Analogue DC | Digital, bidirectional | Mains phase-cut | Wireless Bluetooth mesh |
| Extra wiring | 2 control cores | 2 control cores (polarity-free) | None | None |
| Addressing | None — zone by wiring | Individual, up to 64/line | None | Individual, app-based |
| Feedback / status | No | Yes (fault + hours) | No | Yes |
| Re-zoning later | Rewire required | Software only | Rewire required | Software only |
| Typical dim floor | 1–10% | 0.1–1% | 5–20% | 0.1–1% |
| Relative fixture cost | Low | Higher | Lowest | Higher |
| Best fit | Simple zoned offices, warehouses | Large/complex, future flexibility | Retrofit on existing dimmers | Retrofit where cabling is impossible |
Dim floor and cost vary by driver brand; figures shown are typical for the mainstream commercial drivers used in our fixtures.
0/1-10V — the pragmatic default
A low-voltage DC signal on two extra cores tells the driver how bright to run. It is simple, cheap, vendor-agnostic and almost impossible to get wrong on site. The trade-off is that a "zone" is defined by copper: every fixture on the same pair dims together, so re-zoning an open-plan floor means pulling new cable.
The distinction between 0-10V and 1-10V matters at the bottom of the curve. With 1-10V the driver stays at minimum output at 1V and needs a separate relay or switched live to turn off; with 0-10V many drivers switch off at 0V. Specify which behaviour you need — "dim to off" is a requirement, not a given.
DALI-2 — control as software
DALI (Digital Addressable Lighting Interface, IEC 62386) makes every driver an addressable node on a digital bus. Each fixture can be commissioned into any group or scene from software, and the bus is bidirectional: drivers report lamp failure, and DALI-2 adds certified interoperability plus input devices such as sensors and wall controls.
- Up to 64 addresses per DALI line; larger buildings use multiple lines behind a gateway.
- Polarity-free two-core control cable — usually run alongside mains in the same containment.
- Re-zoning after a fit-out change is a commissioning task, not an electrical one.
- Fault and burning-hours reporting supports planned maintenance in large estates.
The cost is commissioning: someone has to address and group the fixtures, and that skill must exist locally for the building's whole life. For a 40-fixture office DALI is usually over-specified; for a multi-floor building with sensors and scenes it pays for itself the first time the layout changes.
TRIAC — retrofit only, with caveats
Phase-cut dimming chops the mains waveform, so it needs no control wiring at all. That single advantage is why it dominates residential retrofit and 120V North American work: the wall dimmer already exists.
The weakness is matching. A phase-cut dimmer designed for a 400 W incandescent load behaves badly with a 12 W LED driver — the symptoms are a high dim floor, flicker at low levels, audible buzz, or a lamp that drops out entirely. Always request the driver manufacturer's tested dimmer compatibility list and confirm the minimum load of the dimmer is met.
Casambi / Bluetooth mesh — when cable is impossible
Bluetooth mesh puts the control node inside the driver and the interface in a phone or battery wall switch. In a heritage building, a fitted-out shop or any refurbishment where chasing walls is unacceptable, it removes the control-wiring problem entirely, with app-based grouping and scenes comparable to DALI.
Assess it as an IT decision as well as a lighting one: who owns the network keys, who can re-commission the site in three years, and what happens if the specifying contractor is no longer involved. Wireless is excellent where cabling is genuinely impractical, and unnecessary complexity where it is not.
A decision path that holds up
- 1
Is there an existing wall dimmer you must keep?
Yes → TRIAC, and demand the compatibility list. No → continue.
- 2
Can you pull two extra control cores?
No → Bluetooth mesh (Casambi). Yes → continue.
- 3
Will zones or scenes change after handover?
Yes, or sensors and status reporting are required → DALI-2. No → continue.
- 4
Simple fixed zones, cost-sensitive?
0/1-10V. It is the right answer far more often than the market admits.
- 5
Lock it into the specification
State protocol, driver brand, dim floor and dim-to-off behaviour on the schedule — not just the word "dimmable".
Do not forget flicker
Dimming and flicker are separate specifications, and a driver that dims smoothly can still flicker badly at 20% output. Flicker matters for eye comfort, for camera work, and increasingly for compliance in schools and healthcare. Ask for percent flicker and, ideally, the stroboscopic effect visibility measure (SVM) at both full output and low dim levels — not only at 100%, where almost everything looks acceptable.
Frequently asked questions
The questions we field most often when buyers specify dimming for a project.
