The auditor arrives. He walks the building with a clipboard and a torch. Forty minutes later he hands over a defect list. Non-compliant exit signs. Two emergency luminaires with flat batteries. Logbook last updated fourteen months ago. No 90-minute discharge test on record for the last two years.
None of these failures involve the emergency lighting being the wrong brand or the wrong colour temperature. They involve basic compliance requirements that have been in AS 2293 for years, and that the facility manager either did not know about or assumed someone else was handling.
This is the guide that should have existed. What AS 2293 actually requires. What maintained and non-maintained mean, and why electricians mix them up. What lux levels apply where. What the test schedule is and why there is a difference between self-contained and central battery systems. Why LED luminaires can fail on a central DC battery system even when they are brand new and working on mains. And the ten failure modes that auditors find in almost every building they check.
AS/NZS 2293 is a three-part standard. Each part covers a different phase of the system's life, and each is referenced separately in the NCC. All three editions currently referenced by NCC 2022 are:[1]
NCC 2022 references all three under Part E4 (Visibility in an emergency, exit signs and warning systems). A building where the system was designed to 2293.1 but maintained to the wrong intervals under 2293.2 is non-compliant in the same way as a building where the luminaires were never installed at all. The standard is not satisfied partially.
This is the terminology that confuses electricians and facility managers every day. The words sound like they describe maintenance status. They do not. They describe how the luminaire operates relative to the normal lighting circuit.
The luminaire is energised continuously from the mains supply during normal building operation. When mains power fails, it automatically switches to battery. Exit signs are always maintained luminaires. The green pictogram must be visible at all times when the building is occupied. A maintained exit sign that only illuminates during a power failure fails the standard.
The luminaire is off during normal operation and activates automatically when mains power fails. Most emergency escape path luminaires in commercial buildings are non-maintained. They sit dark in the ceiling until needed. The circuit sensing system detects the mains loss and triggers activation within the required response times.
The luminaire has two separate lamp circuits. One operates continuously from mains for general illumination. The second, powered by battery, activates only on mains failure. Sustained fittings are less common in modern installations, where a separate maintained exit sign and non-maintained escape luminaire is the more typical design solution.
The common mix-up. An electrician installs non-maintained emergency downlights on the escape path. During commissioning he switches off the mains circuit and confirms the lights activate. Correct. Then he installs the exit signs on the same circuit, assuming they are non-maintained too. They are not. Exit signs must be maintained. They have to be on at all times. Installing them non-maintained means they are dark when the building is occupied and only illuminate during a test or real emergency. This is a critical defect under AS 2293.2 and must be rectified immediately.
Section 3.3 of AS/NZS 2293.1 sets the illuminance requirements for emergency escape paths. These are not suggestions. They are the numbers the design has to hit, and the numbers the auditor measures when the 90-minute test is running.
| Location | Minimum (centreline) | Minimum (average) | Notes |
|---|---|---|---|
| Escape path: corridor / passageway | 0.2 lux | 0.5 lux | Uniformity ratio must not exceed 40:1 |
| Stairway: each tread | 1.0 lux | Five times the corridor minimum; one fitting per landing rarely sufficient | |
| Open area (anti-panic lighting, >60 m²) | 0.5 lux | 1.0 lux | Applies to areas where people may congregate during evacuation |
| High-risk task area | 10% of normal | Plant rooms, switchrooms, hazardous process areas; must illuminate the task safely |
The 40:1 uniformity ratio catches out designs with widely-spaced fittings. If one point on the escape path is at 8 lux (directly under a fitting) and another is at 0.2 lux (midway between fittings), the ratio is 40:1. Right at the limit. Any further separation or any reduction in fitting output due to battery degradation and the design fails.
The stairway requirement catches out single-fitting designs. One non-maintained downlight at the top of a stairwell does not achieve 1 lux on every tread. A standard 3m flight of stairs, 1.2m wide, typically needs a fitting at the head of the stairs and one midway. High-rise fire-isolated stairwells need luminaires on every landing as a minimum.
AS 2293.1 and NCC Part E4 both set response time requirements for the moment mains power is lost. The system cannot take 30 seconds to illuminate. The requirements are:[2]
LED emergency fittings handle this easily. LEDs reach full output from a battery source in milliseconds. Fluorescent emergency fittings, particularly older magnetic ballast types, often struggled to meet the 15-second requirement at low temperatures. This is one of the practical reasons the transition to LED emergency lighting is well advanced in Australia: the physics of LED suits emergency operation better than fluorescent.
The word "lumens" almost never appears in AS 2293.3 exit sign requirements. The standard uses luminance (candelas per square metre, cd/m²) and viewing distance. These are the two numbers that actually matter.
Exit signs are rated for a specific viewing distance, typically 24 metres for a standard sign and 40 metres for larger signs used in long corridors or warehouses. The exact relationship between pictogram size and rated distance is set out in AS/NZS 2293.3 and depends on the luminance the sign achieves, not on a simple height multiplier. Exit signs must state their rated viewing distance on the face of the fitting. If you cannot read that label, the sign is non-compliant on that basis alone.
The practical consequence:
The "it's on the door" defence does not work. Exit signs must be visible from the direction of approach along the escape path. A sign mounted directly above a fire door is invisible to someone walking towards it from 20 metres away in a low-ceiling corridor. The standard requires the sign to be visible from the approach. Visible along the line of travel, not just at the destination. In practice this means either a ceiling-mounted projecting sign or a sign mounted above the door at the correct height with sufficient luminance to be legible from the approach distance.
AS 2293.1 clause 4.7 sets the mounting height for exit signs: between 2.0 m and 2.7 m above floor level, measured to the bottom of the sign. If the doorway itself is higher than 2.7 m, the sign may be mounted immediately above the doorway.
Exit signs are mandatory at every:[3]
The design decision between self-contained and central battery systems determines the installation cost, the ongoing maintenance cost, and the compliance testing regime. Both are legitimate compliant approaches under AS 2293.1. They are not interchangeable once installed.
Each luminaire contains its own rechargeable battery, typically NiCd, NiMH or LiFePO4. The mains supply charges the battery continuously. On mains failure, each fitting switches to its internal battery independently.
A single central battery system supplies DC power to all emergency luminaires via dedicated sub-circuits. The luminaires themselves have no battery. The central unit charges from mains and supplies all fittings simultaneously on mains failure.
This is the technical failure mode that is causing the most problems in Australian buildings as LED emergency fittings proliferate. It is not obvious, it is not well-documented in mainstream resources, and it results in fittings that appear compliant but fail during the discharge test.
A standard LED luminaire (downlight, panel or batten) is designed to run from 240V AC mains. Inside the fitting is an LED driver that converts 240V AC to the lower DC voltage required by the LED array, typically 24–48V DC depending on the configuration.
A central battery emergency system supplies DC at a fixed voltage. Common Australian central battery system voltages are 24V DC, 50V DC or 110V DC, depending on the system and manufacturer.
The problem: a standard LED driver designed for 240V AC input does not accept 24V DC or 110V DC at its input terminals. The driver will not operate. The LED does not illuminate. The fitting appears to be working on mains (it is: the LED driver is getting its 240V AC) but when mains fails and the central battery system supplies DC, the driver does nothing.
For a LED luminaire to work correctly on a central battery system, one of the following must be true:
The replacement fitting trap. An existing building has a 110V DC central battery system installed in 2008 with fluorescent emergency fittings. The facility manager decides to upgrade to LED and orders standard LED emergency downlights. The electrician installs them. They light up on mains. The 6-monthly test involves a brief visual check. Passes. The LED driver is working fine on mains. At the annual 90-minute discharge test, the mains is isolated. Every fitting goes dark. The central battery is supplying 110V DC. Every LED driver is receiving DC at its input and producing nothing. The building has no emergency lighting. This is a critical defect. The cost to fix it is the same as the original upgrade cost, plus the emergency call-out fee. Every fitting gets replaced.
Before specifying or installing LED luminaires on an existing central battery system, always confirm: What voltage is the central battery system? Is it DC or AC output? Get this in writing from the system documentation or the central battery unit label before ordering a single fitting.
AS 2293.2:2019 sets out the testing and inspection schedule. The schedule differs between self-contained and central battery systems in one important way: self-contained systems require a monthly functional test that central battery systems do not. Both systems require the same 6-monthly and annual tests.
| Frequency | What is done | Applies to | Who performs it |
|---|---|---|---|
| Monthly | Visual inspection of all fittings and signs. Check for damaged covers, obstructions, failed indicator lamps. Also: 30-second activation test of self-contained fittings to confirm battery is holding charge. | All systems; 30-sec test is self-contained only | Competent person; may be in-house |
| 6-Monthly | Full 90-minute discharge test. Mains is isolated. All fittings must illuminate and maintain rated output for 90 minutes. Illuminance readings taken on escape paths. Logbook entry made. For central battery: comprehensive functional test of the whole system including all sub-circuits. | All systems | Licensed electrician or accredited fire protection technician |
| Annual | Full 90-minute discharge test (as above) plus comprehensive maintenance: clean diffusers, check mounting and direction arrows, verify luminaire classifications match design spacing, confirm all fittings are operating at rated output, update logbook with condition report and any defects found. | All systems | Licensed electrician or accredited fire protection technician |
| 10-Yearly / LSL | Light source life (LSL) assessment for LED luminaires. By 50,000 hours of operation, LED output may have degraded below the lumen maintenance threshold (typically L70, meaning 70% of initial output). Assessment determines whether luminaires need replacement to maintain compliant illuminance levels. Also applies at end of rated battery life regardless of hours. | All systems with LED luminaires | Licensed electrician or accredited fire protection technician |
The LSL requirement for LED is new and almost universally missed. AS 2293.2:2019 introduced the light source life (LSL) assessment concept specifically because LED luminaires behave differently from lamps. A fluorescent lamp either works or it does not. An LED array degrades gradually: at 50,000 hours it may still be producing light, but if output has fallen below 70% of initial, the illuminance levels on the escape path may now be below the 0.2 lux minimum even though every fitting appears to be working. The 10-yearly LSL assessment requires checking that actual illuminance levels still meet the standard. Buildings installed in 2016–2018 with the first generation of LED emergency fittings are approaching this threshold now.
Every test, every inspection, every defect found and every rectification made must be recorded in the emergency lighting logbook. AS 2293.2 requires records to be retained for a minimum of 7 years. The logbook must be available for inspection at any time. In NSW, the Annual Fire Safety Statement (AFSS) requires certification that the emergency lighting system has been maintained in accordance with AS 2293. The certifier needs the logbook to sign off that statement.[4]
A logbook that was last updated 18 months ago, or that shows only one test per year instead of two, or that has no record of rectified defects, means the certifier cannot sign off the AFSS. The certifier does not sign it and backdate it as a courtesy. The building owner goes to council without a valid AFSS.
Digital logbook systems, including those built into self-testing emergency luminaire platforms, satisfy the record-keeping requirement. The test data must be downloadable and retained for 7 years. A self-testing system that runs automatic tests but whose results are never downloaded and never reviewed produces an unusable record.
Self-testing LED emergency fittings have a built-in microcontroller that triggers its own discharge cycle on a programmable schedule, stores the test result, and indicates pass or fail via an LED indicator or wireless report. They reduce the labour cost of monthly and 6-monthly testing significantly.
What they solve: the cost of a technician visiting every fitting to trigger a manual test. A building with 80 self-contained emergency fittings that previously required 3–4 hours of technician time every 6 months can largely automate that process.
What they do not solve:
Signs are dark during normal building operation. Occupants have no directional guidance until a power failure occurs. Critical defect. Requires immediate rewiring to a permanent live circuit.
Monthly 30-second tests pass because the battery still charges briefly. The 90-minute duration test exposes fittings that fail after 20–40 minutes. NiCd batteries degrade this way. They appear functional on a short test and fail on a long one.
Monthly visual inspections are being done. The annual 90-minute test has never been performed, or has not been performed in the last 12 months. This is the most common single failure at AFSS time.
Standard LED drivers installed on a DC central battery circuit. Fittings work on mains. Fittings produce no output when central battery supplies DC. See the technical section above for full explanation.
A standard 24m rated sign at the end of a 32m corridor. Nobody read the rated viewing distance on the sign label. The occupant at the far end of the corridor cannot reliably read the sign. Non-compliant design that requires either a higher-rated sign or an intermediate sign.
Single fitting at the top of a stairwell. Centreline lux at the lowest tread measured at 0.3 lux during the discharge test. Fails the 1 lux per tread requirement. Additional fittings required on intermediate landings.
The logbook shows annual tests only. Six-monthly tests were not performed, or were not recorded. The certifier cannot sign off the AFSS without evidence of 6-monthly testing. This failure is purely administrative but has the same compliance consequence as a technical failure.
The original design specified D80 classification luminaires at 6m spacings. A fitting failed and was replaced with a D50 from a different supplier. D50 at 6m spacing does not achieve the required illuminance. The classification must match the design, or the spacing must be recalculated for the replacement fitting.
The emergency lighting system was tripping a circuit breaker during testing. Someone upstream bypassed the circuit sensing relay to stop the nuisance trip. The emergency fittings now only activate when manually triggered, not automatically on mains loss. The system will not activate in a real power failure.
First-generation LED emergency fittings installed 2015–2018 may be approaching 50,000 hours of operation in buildings running 24/7 operations. The LSL assessment under AS 2293.2:2019 has not been performed. Illuminance levels on escape paths may now be below compliance thresholds even though every fitting appears to be illuminated.
LED emergency and exit lighting draws a fraction of the power of fluorescent equivalents. Use the calculator to see the energy cost reduction across your building's emergency lighting load.
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