Emergency lighting is one of the few areas in building automation where paperwork is as important as the hardware. EN 50172 requires documented monthly function tests and annual duration tests for every escape route luminaire. Fail to produce records and the building owner faces enforcement action during fire safety inspections. DALI-2 Part 202 was specifically designed to automate this testing and reporting — when correctly set up with the Helvar Router 950, it eliminates manual testing entirely and generates inspection-ready compliance reports automatically.

DALI-2 Part 202 concept

IEC 62386 Part 202 defines the "self-contained emergency lighting" device type within the DALI-2 standard. A Part 202-compliant electronic control gear (ECG) — either a dedicated emergency driver or a combined normal/emergency driver — has an on-board battery, a charging circuit, and autonomous test intelligence. The ECG does not need an external controller to run tests: it maintains its own test schedule internally and initiates tests independently. The DALI-2 controller (in this case, the Helvar Router 950) can also initiate tests on command and, critically, reads back the detailed test results from each ECG after the test completes. This bidirectional reporting is what makes EN 50172 compliance documentation automatic. Part 202 is distinct from Part 203, which defines "battery-powered emergency lighting" — centrally powered emergency systems with a central battery plant rather than self-contained ECG batteries.

Emergency driver types compatible with Part 202

Two product categories implement Part 202. **Self-contained emergency conversion packs** (Tridonic System 216, Helvar 216 series, Osram Optotronic Safety) retrofit inside an existing luminaire housing, connected in parallel with the existing LED driver. The conversion pack takes over supplying the LED during mains failure. Part 202 intelligence resides in the pack. **Dedicated Part 202 emergency drivers** (Tridonic LCI, Helvar ELD series, Osram DALI-2 EM) are complete LED drivers with integrated emergency function and battery. These replace the standard driver entirely. For new installations, dedicated drivers are the cleaner choice — fewer internal components, fewer potential failure points. For retrofit of existing specified luminaires (architectural fixtures the client insists on keeping), conversion packs are the only option. Verify luminaire housing volume before specifying a conversion pack — some compact LED fixtures cannot physically accommodate the additional pack volume.

Helvar Router 950 commissioning: addressing Part 202 ECGs

The Helvar Router 950 is an IP-connected DALI-2 application controller. Each Router manages one DALI-2 bus (up to 64 ECGs). For an installation with 120 emergency luminaires, you need two Routers on two separate DALI-2 buses, or use the Helvar 910 with multi-bus capability.

Step 1 — Physical installation: Wire each emergency driver to the DALI-2 bus in the normal manner (two-wire DALI pair, polarity-insensitive, bus powered by the Router or dedicated DALI PSU). Ensure each bus does not exceed 64 devices and the 2W bus power limit. Commission the luminaire's LED function first with the existing DALI-2 normal drivers before adding emergency ECGs.

Step 2 — DALI addressing in Helvar Designer: Open Helvar Designer software. Create a new project, add the Router 950 (via IP address). Run DALI scan: Designer discovers all ECGs on the bus and assigns short addresses (0–63). Manually verify the address-to-physical-location mapping (which short address corresponds to which luminaire) — create a floor plan annotation at this stage. It is extremely difficult to identify individual emergency ECG addresses after the ceiling is closed.

Step 3 — Set ECGs to Part 202 mode: In Designer, select each emergency ECG. Set device type to "Emergency (Part 202)". Assign the ECG to the emergency luminaire group. Confirm battery capacity and rated duration (typically 3 hours) match the driver datasheet — Designer uses these values for EN 50172 compliance calculations.

Step 4 — Configure test schedule: In the Router 950 emergency module settings: set function test schedule (monthly, day of week Sunday, time 03:00 — schedule at a time when the building is unoccupied). Set duration test schedule (annually, month August, Sunday at 03:00 — choose the warmest month to test worst-case thermal battery performance). The Router broadcasts the test initiation DALI command to all Part 202 ECGs simultaneously at the scheduled time. Each ECG tests itself independently and buffers the result.

Step 5 — Result retrieval: After the test completes, the Router polls each ECG for its test result object (DALI command 227/228 as defined in Part 202). Results are logged in the Designer database with ECG address, test type, date, duration completed, and pass/fail verdict. Export the log as a PDF report (Designer menu → Reports → EN 50172 Compliance Report). The PDF includes the installation address, router serial number, all ECG addresses tested, dates of function and duration tests, and pass/fail for each — the complete documentation an EN 50172 inspection requires.

Understanding the 7-bit emergency status word

Part 202 defines a standard DALI emergency status object — a 7-bit status word that the ECG returns in response to a DALI "Query Emergency Status" command. The bits and their meanings: **Bit 0 (LSB) — Battery fault:** Set when the battery voltage is below the minimum acceptable level during a test, or the battery cannot accept charge. Indicates battery replacement required. **Bit 1 — Lamp (LED) fault:** Set when the ECG cannot illuminate the LED at the rated output. Could indicate LED array failure or driver fault. **Bit 2 — Duration test pending:** Set when the ECG has not completed a successful annual duration test within the required interval (364 days). Acts as a reminder flag — the test has not failed yet, but is overdue. **Bit 3 — Function test fail:** Set when the most recent monthly function test did not achieve the required result (lamp failed to illuminate, or battery voltage insufficient). This is an active fault requiring immediate action. **Bit 4 — Inhibit active:** Set when the ECG is in the inhibit state (deliberately disabled to prevent testing during planned maintenance). Inhibit expires automatically after 15 minutes. If this bit stays set unexpectedly, investigate whether a software command is continuously re-inhibiting the ECG. **Bit 5 — Test in progress:** Set while the ECG is actively running a function or duration test. Normal during scheduled test window — not a fault. **Bit 6 — Emergency mode active:** Set when the ECG is operating on battery power due to mains failure. This is the operational emergency state, not a fault. The Helvar Designer dashboard polls the status word continuously (configurable interval, typically every 60 seconds) and flags any ECG where Bits 0, 1, or 3 are set. These appear in the Designer fault list and can trigger email notifications via the Router's built-in notification module.

EN 50172 pass/fail criteria

For a monthly function test to pass: the LED must illuminate at full emergency output within 5 seconds of test initiation, and the battery voltage must remain above the minimum operational threshold for 25% of the rated duration (typically 45 minutes for a 3-hour rated ECG). For an annual duration test to pass: the LED must remain illuminated at not less than 50% of rated output for the full rated duration (3 hours minimum). If any luminaire fails a duration test, it must be repaired or replaced before the next scheduled inspection. The EN 50172 record must show the date of failure and the date of remediation. The Helvar Designer report format includes a "corrective action" field alongside each failed ECG — complete this before presenting the report to the fire safety inspector.

Generating compliance reports in Helvar Designer

In Designer, navigate to Reports → Emergency Lighting → EN 50172 Report. Configure: date range (last 12 months for an annual inspection), include both function test and duration test results, select all ECG groups. Designer generates a formatted PDF showing: installation address (taken from project properties — enter this accurately at project creation), Router serial number, report generation date and time, table of all ECGs with short address, luminaire location (from the floor plan annotation), date of last function test, function test result, date of last duration test, duration test result. Print or email the report directly from Designer. Store a copy in the building management documentation folder — EN 50172 requires records to be retained for the life of the installation.

Common fault codes and corrective actions

Battery fault (Bit 0): First check that the luminaire has had adequate time for initial battery charge after installation (typically 24 hours at full mains power). If the fault persists, replace the ECG battery (or the entire ECG if the battery is not field-replaceable). Most Part 202 ECGs have non-user-replaceable batteries and require full ECG replacement. Lamp fault (Bit 1): Check the LED array wiring connections inside the luminaire. If connections are secure, the LED array or driver has failed — replace the ECG or LED module. Function test fail (Bit 3): This is the most common fault in installations over 3 years old and usually indicates a degraded battery. Schedule ECG replacement. If the test fails immediately after installation, check for mains voltage on the DALI bus (a wiring error that destroys ECG electronics — the DALI bus should be 16V DC, never 230V). Duration test pending (Bit 2) after scheduling: If the Router is correctly programmed for annual testing but Bit 2 stays set, check that the Router's real-time clock is correctly set (timezone and DST) and that the DALI bus communication is not interrupted during the scheduled test window. A bus error during the test causes the ECG to abort and set Bit 2. Inhibit active (Bit 4) not during maintenance: Investigate whether a DALI scene or group command is inadvertently sending an inhibit command. Check all DALI scene programming in Designer for unintended emergency inhibit commands — a common error when copying scene configurations between projects.