High-risk task area lighting — the third, stricter category of NEN-EN 1838

The §560 guide on emergency and escape route lighting covers the two most familiar categories under NEN-EN 1838: escape route lighting and anti-panic (open area) lighting. This article covers the third category the standard defines, one that is easy to overlook because it applies only to specific locations, but that carries the strictest requirements of the three: high-risk task area lighting.

What this category protects against

Escape route and anti-panic lighting exist to let people leave a space safely when normal lighting fails. High-risk task area lighting addresses a different problem: at the exact moment normal lighting fails, a person may be in the middle of a task or a process that is itself dangerous to abandon abruptly in darkness — for example someone operating a machine with exposed moving parts, working with molten material, or carrying out a manual step in a process that must be brought to a controlled stop rather than simply interrupted. This category of lighting exists to give that person enough light to either complete the immediate action safely or shut the process down in a controlled way, not to evacuate the whole space.

The illuminance requirement: tied to the task, not a fixed value

Unlike escape route lighting (1 lux along the full width of the route) and anti-panic lighting (0.5 lux at floor level), high-risk task area lighting has no single fixed lux value. Instead, NEN-EN 1838 requires the maintained illuminance to be:

at least 10% of the illuminance normally required for that specific task, and
never less than 15 lux, whichever of the two is higher.

This means the required emergency illuminance scales with how much light the task itself normally needs — a precision task that normally requires very high illuminance under normal lighting demands a higher emergency illuminance than a coarse task, even though both are expressed as "10% of normal," subject to the 15 lux floor.

Uniformity: a stricter ratio than the other two categories

High-risk task area lighting also carries a stricter uniformity requirement than the other categories: the ratio of minimum to maximum illuminance across the task area must be at least 0.1 (that is, the darkest point must be no less than one-tenth of the brightest point). An emergency lighting layout that would be perfectly acceptable for an escape route or an open area can still fail this requirement if it produces sharp local dark patches across the specific task area.

Response time: no staged ramp-up

Escape route and anti-panic lighting are allowed a staged response — 50% of the required illuminance within 5 seconds, 100% within 60 seconds — on the reasoning that a person still has a little time to begin moving toward an exit even before full illuminance is reached. High-risk task area lighting does not get that grace period: the required illuminance level must be reached immediately, or within a maximum of 0.5 seconds. The underlying reasoning is the reverse of escape lighting's: a person mid-task at a dangerous machine or process cannot safely wait several seconds in the dark before deciding how to respond.

Why this is a separate design decision, not an automatic upgrade

Because high-risk task area lighting is markedly stricter (immediate response, task-linked illuminance, tighter uniformity) than the other two categories, it is neither necessary nor efficient to apply it throughout an entire building. It must be identified explicitly, at the specific locations where an abruptly interrupted task or process would itself create a hazard — typically established through the building's own risk assessment, not derived automatically from the escape route or anti-panic lighting design that covers the rest of the space.

Practical relevance

When designing or inspecting emergency lighting in an industrial hall, a laboratory, or any space with machinery or processes that cannot simply be abandoned mid-task, it must be established separately whether any location within that space needs to be classified as a high-risk task area — and if so, that the fixtures serving it are verified against the 10%/15 lux illuminance rule, the 0.1 uniformity ratio, and the 0.5-second response time, not merely against the (less strict) escape route or anti-panic criteria used elsewhere in the same building.

Common mistakes

Assuming NEN-EN 1838 only defines two categories (escape route and anti-panic) and overlooking high-risk task area lighting as a separate, third category with its own, stricter requirements.
Applying the 5-second/50%, 60-second/100% response-time rule of escape route lighting to a high-risk task area — that area requires the full illuminance immediately, or within 0.5 seconds at most.
Treating "10% of normal illuminance" as a fixed lux value instead of calculating it from the task's own normal illuminance requirement (subject to the 15 lux minimum).
Applying high-risk task area lighting everywhere "to be safe" instead of identifying the specific locations where it is actually required — this needlessly complicates the design without improving safety in areas where it does not apply.