Emergency lighting is the part of a building's lighting that is judged entirely on a condition nobody wants to test. It has to work in the dark, on battery, with the occupants moving toward an exit they may not know, and it has to do this reliably years after anyone last thought about it. That combination is why AS/NZS 2293 is less a set of levels than a set of things a design must be able to demonstrate.

The AS/NZS 2293 series currently comprises three parts. AS/NZS 2293.1 covers system design, installation and operation; AS/NZS 2293.2 covers routine service and maintenance; and AS/NZS 2293.3 specifies product requirements for emergency luminaires and exit signs. Designers spend most of their time with Part 1, while building owners and facility managers inherit the ongoing responsibilities addressed by Part 2. Projects are more likely to experience problems when those continuing obligations are not clearly explained at handover.

Edition note. This article refers to the current AS/NZS 2293 series. For regulatory compliance, the edition specifically referenced by the applicable NCC and the requirements of the relevant jurisdiction should always be confirmed.

What the design has to demonstrate

Illuminance along the escape path. The requirement is to maintain a minimum floor-level illuminance along the path of travel for the full emergency duration. This level is low compared with general lighting because the aim is safe movement to an exit, not task performance. The critical point is that it is a minimum along the path: an average across the space is not sufficient, and any dark section between luminaires fails even if the overall average is acceptable.

Duration. During a power outage, the system must deliver the required performance for 90 minutes from a fully charged battery. This drives battery selection and, more often than expected, luminaire spacing, because a fitting's emergency output is only a fraction of its mains output and the calculation must use the emergency-lighting output.

Coverage of the right places. Escape routes, changes of direction, level changes and stairs, exit doors, and the areas where equipment relevant to an emergency is located. Coverage is determined from the escape strategy rather than from the general lighting layout, which is why an emergency design produced by adding a battery to some of the existing downlights usually does not satisfy the standard.

The evidence is a calculation with spacing based on the luminaire's emergency photometric data, not on a rule of thumb about how far apart the fittings look right.

Exit signs and the distance they are read from

An exit sign works only if it is legible from the point at which an occupant first needs it. The standard relates viewing distance to the sign's classification, dimensions and method of illumination. Many commonly used internally illuminated exit signs have a nominated viewing distance of 24 metres; however, the applicable distance must be confirmed for the specific sign and installation.

Two practical consequences follow. Long spaces need more signs than intuition suggests, because the requirement is set by the furthest point from which a decision about direction has to be made. And a sign that is technically compliant but obscured — by a bulkhead, a hanging feature, a later fit-out addition, a display — has failed in the way that matters. Sight lines are part of the design, and they are the first thing a subsequent tenancy fit-out disturbs.

The NCC interface

Which buildings require emergency lighting, and where, is determined by the National Construction Code rather than by AS/NZS 2293. Part E4 of NCC Volume One sets the requirement by building classification and by the characteristics of the space — floor area, occupant numbers, storeys, distance of travel — and calls up the standard for how the system is then designed and installed.

The division matters when scope is being set. The NCC answers, "Is emergency lighting required here?" AS/NZS 2293 answers, "What must the system do, and how is its performance demonstrated?" A project that satisfies one requirement but not the other is not compliant, and the two questions are frequently addressed by different consultants.

The obligation that starts at handover

AS/NZS 2293.2 requires the installed system to be inspected and tested on a defined cycle, including a full-duration discharge test at six-monthly intervals, with results recorded in a log kept for the building. The purpose is straightforward: batteries degrade invisibly, and a system that has never been tested has never been shown to work.

Ongoing inspection and maintenance are generally managed by the building owner or facility manager, but they belong in the handover conversation because two common failure modes are avoidable. A building without an adequate test log lacks evidence that its ongoing inspection and maintenance obligations have been met, regardless of how well the original system was designed. A system designed without regard for how it will be tested — through inaccessible luminaires or no practical means of initiating and managing tests — can also make routine servicing unnecessarily difficult and expensive.

Which aspects are most likely to fail during an inspection

The most common failures are degraded batteries that cannot sustain the required discharge period, faulty luminaires or exit signs, and fittings that fail to operate when the normal power supply is interrupted.

Other issues include inadequate coverage along escape routes, obscured or incorrectly positioned exit signs, faulty testing systems, and incomplete inspection or maintenance records.

What changes during a fit-out

Emergency lighting is designed for a building and then repeatedly disturbed by tenancy works. A new partition creates a path that was not there. A dropped ceiling changes mounting height and therefore spacing. A feature bulkhead cuts the sight line to an exit sign. Additional general-lighting fittings do not contribute to the emergency-lighting provision unless they incorporate an appropriately designed and supplied emergency function.

The check is simple to state and easy to skip: after any change to the layout, escape path, ceiling or partitioning, the emergency design should be reassessed against the new arrangement. A fit-out that leaves the emergency-lighting layout unreviewed may render the installation non-compliant, even where none of the emergency fittings has been physically altered.

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SL Design Consultant is an independent lighting and electrical design consultancy in Sydney, delivering lighting and electrical design across commercial, hospitality, retail, heritage and public projects. Our product-neutral recommendations are guided by design intent, technical performance and project requirements.