DALI-2 Emergency Lighting: IEC 62386 Part 202/203 Fundamentals
Emergency lighting is one of the most regulated areas of building automation. IEC 62386 Part 202 defines how DALI-2 handles self-contained emergency luminaires, while Part 203 covers central battery systems — each with specific ECG behaviour, test protocols, and communication objects that must be correctly commissioned for EN 50172 compliance.
Emergency mode types
EU building regulations and EN 1838 recognise three operating modes for emergency luminaires. Choosing the correct mode for each zone determines lamp life, energy consumption, and the visual behaviour that occupants and fire inspectors will expect to see.
| Mode | Normal operation | Emergency operation | Typical application | EU building type |
|---|---|---|---|---|
| Non-maintained | Lamp off — dark | Lamp on at rated output | Escape route luminaires in offices and warehouses where luminaires would otherwise be off during working hours | Offices, warehouses, industrial |
| Maintained | Lamp on continuously (standard lighting function) | Lamp remains on — same output sustained by battery | Exit signs, corridors, public areas that must always be illuminated and continue illuminated during power failure | Hotels, hospitals, shopping centres, schools |
| Sustained | A portion of the lamp circuit on continuously, remainder off | Full lamp output via battery for additional zones brought into service during emergency | Multi-zone areas where some zones are normally dark (e.g. storage) but must be illuminated on evacuation | Theatres, arenas, multi-purpose halls |
In DALI-2 terms, the mode is configured in the ECG at commissioning time and stored in non-volatile memory. The DALI controller does not need to set the mode on each power cycle — the ECG operates autonomously in the configured mode even without bus communication.
How DALI-2 emergency ECG differs from standard ECG
A standard DALI-2 ECG (Electronic Control Gear — the driver inside the luminaire) receives DAPC (Direct Arc Power Control) dimming commands from the DALI controller and adjusts lamp output accordingly. Its entire operating state is defined by the controller.
An IEC 62386 Part 202 emergency ECG is fundamentally different. It stores its own emergency operating parameters independently of the DALI controller — emergency level, battery status, test results, test schedules, and inhibit flags. This independence is architecturally necessary because in an actual power failure the DALI controller may be off, but the emergency luminaire must still operate correctly.
Autonomous battery management
The ECG continuously monitors its own NiMH or Li-ion battery. Charge state, battery fault flags, and estimated remaining capacity are stored in ECG non-volatile memory and readable via DALI query commands at any time.
Independent test execution
The ECG can initiate its own Automatic Function Test without a command from the controller. The test result (pass/fail, measured duration) is stored locally and polled by the controller during its next scheduled read cycle.
Emergency level pre-programmed
The rated emergency luminous flux (100% output, corresponding to EN 1838 minimum 1 lux at floor level on escape routes) is programmed into the ECG at commissioning and cannot be reduced by a standard DAPC dimming command during emergency operation. The ECG ignores DALI dim commands when running on battery.
Controller failure tolerance
If the DALI bus is disconnected or the controller fails, the Part 202 ECG continues to: charge its battery from the 230V mains supply, execute scheduled tests autonomously, switch to emergency output on mains failure, and store all results for later retrieval when the controller returns to service.
IEC 62386 Part 202 — test features
Part 202 defines two mandatory test types that satisfy EN 50172 requirements. Both can execute autonomously inside the ECG or be initiated by a DALI controller command.
Automatic Function Test (AFT) — monthly
The AFT simulates a mains failure by disconnecting the internal mains supply to the lamp driver and running on battery for a short period (typically 15–30 seconds, sufficient to verify battery presence, battery connection, lamp operation, and charger status). The ECG records the result — pass or fail — with a timestamp in its internal log. The DALI controller polls each ECG periodically using the queryTestResult command and reads the stored result. If the ECG has not been polled since the last test, the result remains available indefinitely in non-volatile storage.
Inhibit during occupied hours
DALI command 253 (Enable DAPC Sequence / Inhibit) instructs the ECG to suppress any pending test for the next 15 minutes. The controller sends this command repeatedly during business hours to prevent a lamp briefly extinguishing (non-maintained mode) in front of occupants. The ECG reschedules the test for the next inhibit-free window — typically the early morning period.
Automatic Duration Test (ADT) — annual
The ADT is a full 3-hour battery discharge test. The ECG runs entirely on battery at rated emergency output for the complete rated duration (EN 50172 requires 3 hours). The ECG measures actual battery runtime in minutes and stores this against the rated duration. A result below 90% of rated duration (less than 162 minutes out of 180) is recorded as a fail and the battery replacement flag is set in queryFailureStatus.
Rest mode after test
After the ADT, the ECG battery is depleted. The ECG enters rest mode — dimming the luminaire to approximately 1% output — during the recharging period (typically 24 hours for NiMH batteries). This avoids the customer complaint of finding all emergency luminaires dark the morning after a scheduled annual test while simultaneously allowing the battery to fully recharge before the next emergency event.
Grid failure simulation — how the test actually works
The DALI controller can also initiate an on-demand test by sending the Start Function Test or Start Duration Test command to any individual ECG or broadcast to all emergency ECGs in the system. The ECG immediately disconnects its internal mains path to the lamp driver, switches to battery supply, runs at full emergency output, and measures elapsed time on battery. On test completion or mains restoration, the ECG stores the measured duration and pass/fail result. This on-demand method is used for commissioning verification and for ad-hoc compliance spot checks by facility managers.
DALI-2 Part 202 communication objects
Part 202 adds a set of query commands beyond the standard DALI command set. The DALI controller uses these to poll each emergency ECG and build the compliance log required by EN 50172.
| DALI command | Return type | Description |
|---|---|---|
| QUERY EMERGENCY STATUS | 7-bit word | Bit 0: inhibit active; Bit 1: function test pending; Bit 2: duration test pending; Bit 3: battery fault; Bit 4: lamp fault; Bit 5: function test done; Bit 6: duration test done. Primary health status poll. |
| QUERY BATTERY CHARGE | 8-bit value | Estimated battery charge as percentage 0–100%. Value 255 indicates battery fault or charge not measurable. Useful for predictive battery replacement scheduling. |
| QUERY TEST RESULT | 8-bit value | Result of last completed function or duration test: 0 = test not yet executed; Bits 0–6: duration in minutes (0–127 min); Bit 7: pass (1) or fail (0). |
| QUERY FAILURE STATUS | 8-bit word | Bit 0: battery fault; Bit 1: battery duration fault; Bit 2: lamp fault; Bit 3: circuit fault. Any non-zero value requires maintenance action. |
| QUERY EVENT FILTER (ZERO TO ONE) | 8-bit mask | Returns which event transitions will generate an unsolicited DALI event from this ECG — allows controller to subscribe to push notifications rather than polling. Reduces bus traffic in large installations. |
| START FUNCTION TEST | No return | Controller-initiated AFT. ECG disconnects mains to lamp driver, runs on battery, stores result. Same as autonomous AFT but triggered on demand. |
| START DURATION TEST | No return | Controller-initiated ADT. Full 3-hour drain test. ECG stores result — pass/fail and measured duration in minutes. |
| INHIBIT | No return | Suppresses any pending test for the next 15 minutes. Must be sent repeatedly (every 14 minutes or less) to maintain inhibit state during occupied periods. |
Helvar Router 950 as the standard DALI-2 emergency controller
The Helvar Router 950 is the de-facto standard DALI-2 controller for commercial emergency lighting projects in Northern and Central Europe. It operates as a multi-master DALI-2 controller — the bus can have up to 64 devices per segment, and the Router 950 supports multiple DALI segments via its module slots.
Automated poll cycle
The Router 950 polls every Part 202 ECG on its DALI segments on a configurable schedule (default: every 60 seconds for status, hourly for full test result readback). All results are stored in the Router's internal SQLite database with a timestamp — this database constitutes the EN 50172 logbook.
Helvar Designer software integration
The Helvar Designer configuration software connects to the Router 950 over IP and displays a live dashboard of all emergency ECG states — green (pass), amber (test pending), red (fault). Test schedules, inhibit time windows, and report generation are all configured in Designer.
PDF compliance reports
The Router 950 can generate EN 50172 compliant PDF test reports on demand or on a scheduled basis (e.g. monthly on the first day of each month). The report lists every emergency luminaire by address, test date, test type, result, and measured duration. This document satisfies building insurance and fire authority inspection requirements.
KNX integration via HelvarNet gateway
The Router 950 connects to the KNX bus via the Helvar HelvarNet KNX gateway. Emergency fault states and test completion events are written to KNX group addresses, allowing the building management system or home automation controller to receive push notifications, log faults to a central database, and trigger SMS or email alerts to the site manager.
Fault escalation workflow
When a DALI-2 ECG raises a lamp fault or battery fault flag, the Router 950 detects it within one poll cycle. It writes a fault flag to the corresponding KNX group address. The HA system (e.g. KNX Logic Module or IP gateway) pushes a mobile notification to the responsible engineer with the exact luminaire short address, fault type, and timestamp. EN 50172 requires the fault to be corrected within 24 hours.
Helvar Router 950 — KNX group address mapping (example)
// Emergency DALI segment → KNX group addresses (HelvarNet gateway) Emergency segment 1 (Floor 1 escape routes) Segment fault (any ECG) → GA 8/0/1 (DPT 1.001 — 0=OK, 1=FAULT) Function test complete → GA 8/0/2 (DPT 1.001 — 1=test done, resets) Duration test complete → GA 8/0/3 (DPT 1.001 — 1=test done, resets) Battery fault count → GA 8/0/4 (DPT 5.010 — number of ECGs with battery fault) Lamp fault count → GA 8/0/5 (DPT 5.010 — number of ECGs with lamp fault) Individual ECG fault (short address 01, Floor 1 stairwell) Lamp fault → GA 8/1/1 (DPT 1.001) Battery fault → GA 8/1/2 (DPT 1.001) Last test result → GA 8/1/3 (DPT 5.010 — duration minutes) Battery charge % → GA 8/1/4 (DPT 5.001)
Illuminance requirements — EN 1838
EN 1838 defines the minimum illuminance levels that emergency luminaires must provide. The DALI-2 emergency ECG is pre-programmed at commissioning to deliver 100% rated output during emergency operation, regardless of any DALI dimming command received — this ensures the EN 1838 minimums are maintained at all times.
| Zone type | Minimum illuminance | Measurement point | Notes |
|---|---|---|---|
| Escape route (corridor, stair) | 1 lux minimum | Floor level along centre line | Uniformity ratio: minimum / maximum illuminance ≥ 1:40 along escape route centre line |
| Open area (anti-panic lighting) | 0.5 lux minimum | Floor level anywhere in the area | Required for open areas > 60 m² where people may panic if unlit. Uniformity ratio ≥ 1:40. |
| High-risk task area | 10% of normal or 15 lux (whichever is greater) | Working plane at task position | Applies to areas where sudden loss of lighting constitutes a safety hazard — machine rooms, labs, operating theatres |
Illuminance calculations are performed during design using photometric software (DIALux, Relux). The DALI-2 emergency ECG rated lumen output and luminaire geometry determine whether EN 1838 minimums are achieved. Once installed, the DALI-2 Part 202 system verifies the lamp is operational — it does not re-measure floor illuminance. Physical photometric verification is required at commissioning.
Emergency lighting in your panel
PanelCraft designs panels with dedicated DALI-2 emergency circuits, physically separated from standard lighting, pre-commissioned and tested before delivery — with EN 50172 documentation package included.
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