What this article helps you plan
- How to calculate zones, luminaire quantities, DT8 control channels and total 24V load.
- How to choose between distributed DALI controllers, DIN rail power supplies and integrated devices.
- Which DALI bus wiring rules, address groups and commissioning checks matter in a residential project.
- How a practical BOM for TILLUME 24V LED spots, DALI DT8 controllers and power supplies comes together.
After weeks of planning the smart home concept, the system-level decision is clear: KNX as the backbone, with lighting controlled via a KNX-DALI gateway. The choice of KNX+DALI over KNX LED actuators comes down to a practical advantage — the DALI ecosystem offers a much wider range of dimming devices from multiple manufacturers, avoiding lock-in to the handful of KNX actuator suppliers and making future replacements far easier. With the architecture in place, the next step is the lighting layout: how many fixtures per zone, what control logic, which luminaires. A rough layout sketch exists — but what is still missing is a concrete electrical plan: which DALI controller, how large a power supply, how to route the bus, how to assign addresses. Without a component list, none of that can move forward.
This article walks through the complete DALI-2 system planning and commissioning process using a real project as the example. A common German single-family home layout: living room (35 m²) + dining and bar area (15 m²) + kitchen (15 m²) — approximately 65 m² of open-plan living space with 34 DT8 fixtures in total (18 + 5 + 8 + 3, i.e. spotlights in living room, dining table, kitchen, and bar pendant luminaires) plus 2 strips of 5 m each of tunable white LED strip (living room accent lighting), all connected to a single DALI bus, driven by TILLUME 24V constant-voltage DALI controllers, with the upper layer connected to KNX via a KNX-DALI gateway. This is not an installation manual — but after reading it, you will know what components a correct system requires, what specifications to define for each, what wiring rules apply, and what to verify at handover: enough to complete the electrical plan yourself.
The DALI-2 lighting control guide series
Start here if you are planning a DALI-2 lighting system for a home or renovation project. The series moves from everyday benefits to DT6 dimming, DT8 Tunable White, scene programming, D4i, KNX integration and practical system planning.
A practical, homeowner-focused introduction to what DALI-2 changes in everyday lighting comfort. D2-02. DALI DT6 Dimming
Understand precise 1-100% dimming, digital control and why DT6 feels different from conventional dimmers. D2-03. DALI DT8 Tunable White
Plan colour-temperature control for daylight simulation, comfort scenes and different times of day. D2-04. Programming DALI Light Scenes
Create practical lighting scenes for living rooms, kitchens, corridors and evening routines. D2-05. D4i and Intelligent Lighting Data
Learn how D4i adds energy, status and maintenance data to professional lighting systems. D2-06. Combining DALI and KNX
See how DALI lighting control and KNX building automation work together through gateways.
Select controllers, power supplies, components and wiring architecture for a reliable DALI-2 system.
Requirements Analysis: Calculate Before You Shop
The first step in system planning is not opening a product catalogue — it is first calculating the number of luminaires from room areas, then answering three core questions. This section walks through the complete derivation process using a specific German single-family home ground-floor living area as the example.
Step 1: Define Zone Areas and Target Illuminance
The luminaire quantity calculation is based on DIN 5035-3 residential lighting standards:
| Zone | Area | Target Illuminance (per DIN 5035-3) |
|---|---|---|
| Wohnzimmer (Living Room) | 35 m² | 150 lx (general activity) |
| Essbereich (Dining + Bar) | 15 m² | 150 lx (dining scenario) |
| Küche (Kitchen) | 15 m² | 300 lx (worktop surface) |
Step 2: Calculate Required Luminaire Quantities
Formula: Required qty = Target illuminance (lx) × Area (m²) ÷ (Luminaire luminous flux × Utilisation factor × Maintenance factor)
Parameters:
- Luminaire luminous flux (measured values, from TILLUME LED Spot Master CRI95 integrating sphere test report — see product spec sheet):
| Colour Temperature | Measured Luminous Flux |
|---|---|
| 2200 K (warm end) | 500 lm |
| 4000 K (primary daytime scenario) | 720 lm |
| 6500 K (cool end) | 800 lm |
4000 K is used as the representative colour temperature for the full-home primary-use case. For mixed-mode operation, actual luminous flux depends on the colour temperature ratio — use the 4000 K endpoint as a reference.
- Utilisation factor: 0.5 (beam angle diffusion loss + wall/furniture absorption)
- Maintenance factor: 0.8 (5-year lumen depreciation headroom)
- Effective flux at 4000 K: 720 × 0.5 × 0.8 = 288 lm/unit
| Zone | Area | Target Lux | Theoretical Qty (4000K) | Practical Recommendation |
|---|---|---|---|---|
| Wohnzimmer (Living Room) | 35 m² | 150 lx | 35×150÷288 = 18.2 units | 18 units (+ strips for combined illuminance) |
| Essbereich Dining Area | 15 m² | 150 lx | 15×150÷288 = 7.8 units | 5 units (+ bar pendant luminaires supplement) |
| Küche (Kitchen) | 15 m² | 300 lx | 15×300÷288 = 15.6 units | 8 units (under-cabinet strip preferred) |
Step 3: Answer Three Core Questions
Question 1: How many DALI control channels are needed?
Each group of luminaires requiring independent brightness or colour temperature control needs a separate DALI control channel. This project's zones have different control requirements:
- Wohnzimmer (Living Room): 18 × DT8 spotlights (144 W, >120 W/controller) → 2 × DT8 channels (9 spots per channel); 2 × LED strips (5 m / 120 W each) independently controlled → 2 × DT8 channels (one strip per channel)
- Essbereich Dining Area: 5 × DT8 spotlights → unified colour temperature + dimming → 1 × DT8 channel
- Essbereich Bar Area: 3 × DT8 pendant luminaires → unified colour temperature + dimming → 1 × DT8 channel
- Küche (Kitchen): 8 × DT8 spotlights → unified colour temperature + dimming → 1 × DT8 channel
Conclusion: a minimum of 7 DALI control channels (7 × DT8).
Question 2: DT6 or DT8?
The rule is straightforward: if colour temperature adjustment (cool white/warm white switching) is desired anywhere, DT8 is required; if dimming-only control is sufficient, DT6 is adequate and less expensive. In this project, the homeowner has chosen tunable white throughout — living room, dining table, bar counter, and kitchen all on DT8. The reason: consistent colour temperature across the open-plan space feels natural; having DT8 in the living room but a different colour temperature in the adjacent kitchen and dining area would create a disjointed experience.
Question 3: What is the total power consumption?
Calculate nominal total power to size the power supply:
| Item | 8W Version | 6W Version |
|---|---|---|
| Wohnzimmer DT8 spotlights × 18 | 144 W | 108 W |
| Essbereich Dining DT8 spotlights × 5 | 40 W | 30 W |
| Essbereich Bar DT8 pendant luminaires × 3 (light source purchased separately) | 24 W | 18 W |
| Küche DT8 spotlights × 8 | 64 W | 48 W |
| Wohnzimmer LED strips × 10 m | 150 W | 150 W |
| Total | 422 W | 354 W (108+30+18+48+150) |
Choose 8W or 6W based on illuminance requirements. The 8W version provides higher brightness and greater power headroom; the 6W version has lower total power consumption and less heat generation. This project uses the 8W version as the baseline for power supply calculations; the 6W version is provided for reference.
Power Supply Architecture: External PSU vs. Integrated Device
Two mainstream approaches exist for the control layer of a DALI lighting system:
Approach A: DALI Controller + External PSU
The controller handles DALI dimming/colour temperature control only; the power supply is purchased separately. This project uses a distributed architecture: three 170W switching power supplies are centrally installed on DIN rails inside the distribution cabinet, feeding 24V power cables to zone nodes. Seven DALI DT8 controllers are distributed across zone locations (surface or junction box mounting), connected to LED loads via short output cables. The DALI bus runs independently (2-core control cable, low current, long-distance capable), connecting all controllers back to the KNX-DALI gateway in the distribution cabinet.
Approach A advantages: faulty controller is replaced independently, faulty power supply is replaced independently.
Disadvantages: more complex wiring; cable loss must be considered.
For this project, TILLUME's CCT DALI LED Controller (C22 series) are selected — 7 units in total, distributed across zone nodes:
- Living Room spotlights (18 × DT8, 144 W): 2 × TILLUME CCT DALI DT8 Controller (9 spots each, ≤120 W/channel)
- Living Room strips (2 × 5 m, 2 × 75 W): 2 × TILLUME CCT DALI DT8 Controller (1 channel per strip)
- Dining Area (5 × DT8 spotlights, 40 W): 1 × TILLUME CCT DALI DT8 Controller
- Bar Area (3 × DT8 pendant luminaires, 24 W): 1 × TILLUME CCT DALI DT8 Controller
- Kitchen (8 × DT8 spotlights, 64 W): 1 × TILLUME CCT DALI DT8 Controller
Approach B: AC/DC Integrated Power Supply
Power supply and controller are integrated into one device — wiring is simpler. The disadvantage is that if either the controller or the power supply fails, the entire unit must be replaced. This project uses Approach A, for two reasons: ① the 170W switching power supplies are centrally mounted on DIN rails in the distribution cabinet, providing greater power headroom; ② the controllers are distributed at zone nodes, so a faulty controller is replaced independently, and a faulty power supply is replaced independently — neither affects the other.
| Approach | A: DALI Controller + External PSU | B: AC/DC Integrated PSU |
|---|---|---|
| Advantages | Independent maintenance (controller or PSU replaced separately); power supplies centrally in cabinet, greater headroom | Simpler wiring: integrated unit, fewer power cables |
| Disadvantages | More complex wiring; cable loss must be evaluated | Controller or PSU failure requires full unit replacement |
| Best for | Projects prioritising long-term maintenance convenience | Projects with fewer luminaires and limited wiring space |
Power Supply Sizing: Wattage, Efficiency, and Headroom
The core principle: Nominal power × 1.2 (+20% headroom) ≤ power supply rated power.
Why the 20% headroom? LED luminaires draw a higher inrush current at startup than at steady state, and a power supply running near full load generates more heat and has a shorter lifespan. The headroom also provides space for future luminaire additions.
For this project's total power of 422 W (8W version):
- With headroom: 422 W × 1.2 = 506.4 W
- Recommended power supply: 3 × 170 W (total 510 W)
Selection: TILLUME 24V constant-voltage DIN rail switching power supply (model: HDR-170-24, 170 W × 3 units), featuring the latest GaN (gallium nitride) technology in a compact 4 SU (70 mm) form factor — comparable power density to the best DIN rail LED power supplies available in the European market, with efficiency ≥94%. Centrally mounted on DIN rails in the distribution cabinet, delivering 24V to each zone's DALI DT8 controller. Total capacity 510 W, ample headroom (422 W ÷ 510 W = 82.7%), low heat generation, long service life.
Wiring Design: DALI Bus Rules and Common Pitfalls
DALI bus wiring is more flexible than KNX, but several key rules must be observed.
Core DALI Bus Wiring Rules
- Conductor specification: Only a 2-core cable is required (no shielding needed), identical to standard lighting wiring. The DALI bus is a low-voltage bus (16 V DC), with more relaxed wiring requirements than KNX — however, maintaining adequate spacing from 230 V mains cables is still recommended to minimise inductive interference risk.
- Bus topology: DALI supports Free Topology — star, tree, line, and any combination thereof are all permitted, but loops are not allowed (the same cable must not connect both ends of one device). In our project experience, all three zones — living room, dining area, and kitchen — use tree wiring from the distribution cabinet to each luminaire — the cleanest layout.
- Maximum bus length: Standard DALI bus maximum length is 300 m (conductor cross-section ≥ 1.5 mm²). For typical residential installations (total bus length usually 50–80 m), this limit is rarely triggered.
- Device count: A single DALI bus supports a maximum of 64 device addresses. This project: 7 × controllers (1 DALI address each) = 7 DALI device addresses — easily satisfied; all 34 DT8 luminaires (including 3 bar pendant light sources) + 2 LED strips are connected via the controllers and do not consume independent DALI device addresses.
- Separation from mains wiring: When DALI bus runs parallel to 230 V mains cables, maintain at least 10 cm spacing; when crossing, maintain perpendicular routing. Unlike KNX, DALI has higher immunity to interference, and short parallel runs typically do not cause communication faults.
Address Allocation: Two Practical Strategies
DALI addresses (0–63) determine which luminaires are in the same control group and which lights respond simultaneously when a scene is called. Two common allocation strategies exist:
Strategy A: Allocate by Zone (suitable for residential projects)
Each room or functional area occupies an independent DALI group. This approach is intuitive; scene programming follows a clear by-room logic. This project:
- Group 0 (Living Room Spotlights): DT8 channel, 18 × DT8 spotlights (2400–6500 K)
- Group 1 (Living Room Strips): DT8 channel, 2 × 5 m LED strips (independently controlled colour temperature and brightness)
- Group 2 (Dining Area): DT8 channel, 5 × DT8 spotlights
- Group 3 (Bar Area): DT8 channel, 3 × DT8 pendant luminaires
- Group 4 (Kitchen): DT8 channel, 8 × DT8 spotlights
The five groups operate independently — when the living room is dimmed, the kitchen and dining areas retain their own brightness levels without interference; the living room LED strips can also be adjusted independently, unaffected by the spotlight brightness.
Strategy B: Allocate by Function (suitable for complex commercial projects)
Different functional layers within the same room occupy separate groups. For example: primary lighting, accent lighting, and ambient lighting are each in different groups, allowing independent control. This approach is more flexible but involves more complex configuration logic.
Recommendation: For ordinary residential projects, Strategy A (by zone) is sufficient. Luminaires within the same group share the same brightness setting; between groups, control is entirely independent — no additional DALI address separation is needed.
Installation and Commissioning: From Power-Up to Scene Programming
Installation and commissioning are handled by the integrator or qualified electrician, but the homeowner needs to know the acceptance criteria. This stage has four steps:
Step 1: Power-Up and Basic Function Verification
- Power each controller individually; confirm DALI bus communication is normal (controller LED indicator is steady, no frequent flashing)
- Test each luminaire's basic functions: on/off, dimming (full range 1%–100%), colour temperature switching (DT8 channel)
- Verify System Failure Level: disconnect the DALI bus to simulate a fault; confirm luminaires automatically switch to the preset safety brightness
Step 2: Group and Scene Configuration
- Allocate Groups according to plan (living room spotlights = Group 0, living room strips = Group 1, dining = Group 2, bar = Group 3, kitchen = Group 4)
- Configure 4 basic scenes:
- Everyday mode: living room 4000 K/80%, kitchen 3000 K/100%, dining area 3000 K/70%
- Cinema mode: living room 3000 K/15%, kitchen off, dining area 2700 K/10%
- Morning mode: living room 3500 K/60%, kitchen 4000 K/100%, dining area 3500 K/60%
- Late-night mode: living room 2700 K/5%, kitchen off, dining area off
- Configure Fade Time: cinema mode and late-night mode use a 5-second fade (no sudden changes); everyday and morning modes use a 1-second fade (snappier response feel)
Step 3: KNX Panel Binding (if applicable)
If a KNX panel triggers DALI scenes, the integrator must bind KNX Group Addresses to DALI scene numbers in ETS. At acceptance, test:
- Each KNX button triggers the correct DALI scene
- Scene fade time matches the setting
- Cross-system automation (if any) operates correctly
Step 4: Acceptance Checklist
The homeowner and integrator jointly confirm the following:
- On/off, dimming, and colour temperature (DT8) functions for every luminaire are normal
- Living room, kitchen, and dining area each control independently
- All 4 scenes respond correctly
- KNX panel binding (if applicable) is error-free
- System Failure Level fail-safe function has been tested
- DALI bus shows no persistent communication errors (no error log in the controller)
Cost Estimate: Example Project BOM and Reference Pricing
Below is the complete BOM (Bill of Materials) for this project with confirmed TILLUME retail prices (German market):
| Component | Reference Model | Qty | Unit Price (EUR) | Subtotal (EUR) |
|---|---|---|---|---|
| DT8 LED Spotlights (living room 18 + dining 5 + kitchen 8) | TILLUME Master CRI95 DT8 Spot 2400–6500 K 8W | 31 | 32.77¹ | 1,014.87 |
| MR16 Round Adjustable Recessed Frame | TILLUME Round Adjustable Recessed LED Frame | 31 | 5.20 | 161.20 |
| CCT LED Pendant Luminaire (Bar, housing only) | TILLUME CCT LED Pendant Luminaire (Ø60mm, cable 1.3 m) | 3 | 24.56 | 73.68 |
| DT8 LED Spot (Bar pendant light source, purchased separately) | TILLUME Master CRI95 DT8 Spot 2400–6500 K 8W | 3 | 32.77¹ | 98.31 |
| CCT COB Seamless LED Strip | TILLUME CCT 24V COB LED Seamless Strip (5 m/roll) | 2 rolls | 55.25 | 110.50 |
| DALI DT8 Controller (distributed zone installation) | TILLUME CCT DALI LED Controller C22 24VDC 5A DT8 | 7 | 27.68 | 193.76 |
| DIN Rail Switching Power Supply 170W (centralised in cabinet) | TILLUME 24V 7A 170W DIN Rail Power Supply | 3 | 63.79 | 191.37 |
| DALI Bus Cable | 2-core control cable (supplied by electrical contractor) | — | — | — |
| Total (Master version, incl. volume discount) | €1,843.69 | |||
¹ Unit price includes volume discount (≥10 pcs = additional 5% off; list price €34.49 → discounted €32.77)
Not included: DALI bus wiring materials (typically supplied by the electrician), KNX-DALI Gateway (if applicable), and installation labour.
Cost-Reduction Option — Expert version (CRI90): If budget is a concern, the Expert version DT8 spotlight (€28.34/unit, no volume discount) is available. DT8 spotlight cost: 28.34 × 31 = €878.54; project total: approx. €1,707.36 — saving €136.33 vs Master version.
Product Selection: TILLUME's Complete 24V Constant-Voltage DALI Solution
TILLUME does not offer just a single controller — it provides a tested and matched 24V constant-voltage DALI lighting system: switching power supplies, DALI LED controllers, and 24V constant-voltage LED spots that work together, verified for mutual compatibility through real-world testing. Power supplies are centrally installed on DIN rails in the distribution cabinet; DALI DT8 controllers are distributed to zone nodes.
- DT8 LED Spot (all zones): TILLUME Master CRI95 DT8 LED Spot 2200–6500K 8W, CRI95, flicker-free, MR16 pin compatible
- Recessed Mounting Frame (all spots): TILLUME Round Adjustable Recessed LED Frame, Ø85mm outer, Ø68mm cut-out, IP20, matte white/black
- CCT LED Pendant Luminaire (Bar): TILLUME CCT LED Pendant Luminaire, Ø60mm × H300mm, cable 1300mm (adjustable), aluminium, IP20, black / white
- CCT COB Seamless LED Strip: TILLUME CCT 24V COB LED Seamless Strip, 15W/m, CRI95, 5 m/roll, seamless (no visible dots)
- DALI DT8 Controller (×7, distributed zone installation): TILLUME CCT DALI LED Controller C22 24VDC 5A DT8, surface/junction-box mounting at zone nodes, max 120W/channel, 2400–6500K DT8, 4 kHz PWM
- DIN Rail Switching Power Supply (×3, centralised in cabinet): TILLUME 24V 7A 170W DIN Rail Power Supply, efficiency ≥94% (SiC/GaN), HDR-170-24, TS-35 rail, IP20, all 3 units mounted on DIN rails in the distribution cabinet
FAQ
References
| # | Reference | Source | Link |
|---|---|---|---|
| [1] | IEEE 1789 – PWM dimming frequency and health risk standard (no-risk threshold: ≥3 kHz) | IEEE Standard | standards.ieee.org |
| [2] | DALI protocol IEC 62386 standard system | DALI Alliance | www.dali-alliance.org/handbook |
TILLUME Product Data (used as measured values in the article, not cited as external reference):
- 4 kHz PWM dimming frequency (nominal, all TILLUME DT6/DT8 controllers)
- System Failure Level configurable (product feature)
- 170W DIN rail power supply efficiency ≥94% (measured, SiC/GaN)
- DT8 Master 8W measured luminous flux: 2200K = 500 lm, 4000K = 720 lm, 6500K = 800 lm (integrating sphere, see doc.tillume.com)
D2-07 EN body | v1.22 | 2026-04-24 | TILLUME