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Last reviewed: 19 September 2026 · By the Dad‑Link Emergency Lighting Division
What Is an Illuminance Verification Report?
An illuminance verification report records the actual light levels an emergency lighting installation produces, measured in lux, and compares them against the minimum levels required by BS EN 1838:2013. For each measurement point it captures the area type, the required minimum, the measured reading, the uniformity ratio and a clear pass or fail.
Most emergency lighting testing checks that luminaires operate and last their rated duration. That is necessary but not sufficient: a luminaire can switch on and run for three hours while still leaving part of an escape route too dark to use safely. The illuminance report is the piece that proves the light actually reaching the floor meets the standard — the difference between “the emergency lights work” and “people can see to escape”.
It is one of the accepted forms of photometric evidence in BS 5266‑1, so it can stand alone or accompany a completion certificate, a site compliance certificate (where it is especially valuable when no design data survives), or a periodic certificate.
The BS EN 1838 Minimum Lux Levels
These are the numbers everyone searches for. They are minimum maintained illuminances at floor level, at the end of the rated duration.
| Area | Minimum lux | What it means |
|---|---|---|
| Escape route — centre line | 1 lux | Along the centre line of a defined escape route up to 2 m wide, measured on the floor. |
| Escape route — central band | 0.5 lux | Across the central band of the route (the middle half of its width). |
| Open (anti‑panic) area | 0.5 lux | The empty core of an open area, excluding a 0.5 m border round the walls, to let people reach an escape route. |
| High‑risk task area | 10% of normal, min 15 lux | Enough light to shut down a dangerous process safely — 10% of the normal task illuminance, but never below 15 lux. |
Area Types Explained
The right minimum depends on what the area is for. Getting the classification right is half the job — measure a corridor against the open‑area figure and you’ll pass points that should fail, and vice versa.
Escape routes
The defined paths people follow to leave the building — corridors, stairs, the route to a final exit. The demanding point is the centre line at 1 lux; the wider central band needs 0.5 lux. Emphasis points (changes of direction, stairs, exit doors, fire‑fighting equipment and call points) need particular attention because that is where people hesitate.
Open (anti‑panic) areas
Larger open spaces greater than about 60 m² — open‑plan offices, halls, retail floors — where the risk is panic rather than a defined path. The core of the space needs 0.5 lux so people can see well enough to reach a route, ignoring a 0.5 m strip around the perimeter.
High‑risk task areas
Places where a sudden loss of light is itself dangerous — a moving machine, a process that must be shut down, a raised platform. Here the requirement scales with the normal lighting: 10% of the normal task illuminance, and never less than 15 lux. If the normal level is 500 lux, the emergency minimum is 50 lux; if it’s 100 lux, the 15‑lux floor applies.
Uniformity Ratios — Why the Dark Patches Matter
Meeting the minimum at one point isn’t enough if the light is wildly uneven. A corridor that reads 20 lux under each fitting but drops to 0.3 lux midway between them has a bright‑and‑dark stripe pattern that is disorienting in an emergency. BS EN 1838 controls this with a uniformity ratio — the highest illuminance in an area divided by the lowest.
- Escape routes and open areas: the ratio must be no worse than 40:1.
- High‑risk task areas: no worse than 10:1.
In practice you record the lowest reading at each point (the value that must meet the minimum) and, where you want to demonstrate uniformity, the highest reading in the same area. The report divides one by the other and flags any area that breaches the ratio — a point can meet the minimum lux and still fail on uniformity.
How to Measure Correctly
A reading is only as good as the conditions it was taken in. Get these right and the numbers stand up to scrutiny.
Normal lighting off
Switch off (or simulate the failure of) the normal lighting so you are measuring only the emergency contribution.
Daylight excluded
Close blinds or test after dark. Daylight through a glazed door will inflate a reading and hide a real shortfall.
At the end of the duration
The worst case is at the end of the rated duration when batteries are nearly discharged. Measuring at minute one flatters the system.
On the floor
Escape‑route and open‑area minimums are floor‑level figures. Lay the meter on the floor, not at waist height.
The right points
Measure the darkest points — midway between luminaires, at emphasis points, in corners of open areas — not just under the fittings.
Record the conditions
Note whether normal lighting was off, whether daylight was excluded, and any ambient light. It’s part of the evidence.
Worked Examples
Four measurement points from a real verification, and the verdict on each.
| Ref | Location | Area type | Required | Lowest | Highest | Ratio | Result |
|---|---|---|---|---|---|---|---|
| P1 | Corridor B, centre line | Escape route | 1.0 | 1.8 | 22 | 12:1 | Pass |
| P2 | Corridor B, midway between fittings | Escape route | 1.0 | 0.6 | — | — | Fail |
| P3 | Open office core | Open area | 0.5 | 0.7 | 9 | 13:1 | Pass |
| P4 | Packing line (normal 300 lux) | High‑risk | 30 | 34 | 60 | 1.8:1 | Pass |
Reading the points
- P1 passes comfortably at 1.8 lux against a 1‑lux minimum, with a healthy 12:1 ratio.
- P2 is the important one: midway between two luminaires the level drops to 0.6 lux — below the 1‑lux escape‑route minimum. This is exactly the dark patch a spot check under the fittings would miss. It needs an added or repositioned luminaire, then a re‑measure.
- P3 passes the open‑area 0.5‑lux minimum at 0.7 lux.
- P4 is a high‑risk area with a normal level of 300 lux, so the minimum is 30 lux (10%). At 34 lux it passes, with an easy 1.8:1 ratio well inside the 10:1 limit.
Standards & References
- BS EN 1838:2013 — lighting applications, emergency lighting. The source of every lux figure and uniformity ratio on this page.
- BS 5266‑1:2016 — the UK code of practice. Annex D covers the measurement and verification of illuminance; it recognises site light readings as photometric evidence.
- SLL Lighting Guide LG12 — the Society of Light and Lighting’s guidance on emergency lighting design, widely used alongside the standards.
- BS EN 50172:2004 / BS 5266‑8:2004 — the testing and record‑keeping regime the report feeds into.
The illuminance report is BS EN 1838’s numbers made real: you take the required minimums from the standard, measure the actual levels on site, and document the comparison as evidence for the BS 5266‑1 certificate.
Recording It in Lux Meter Pro
This is the one report where the app’s built‑in light meter does the actual measuring — read the lux and record it in the same tap.
Set the conditions
Normal lighting off, daylight excluded, emergency lighting at the end of its rated duration.
Open a report
Choose Illuminance Verification Report, add the site details, and record the meter model and calibration.
Pick the area type
For each point choose escape route, open area, or high‑risk. For high‑risk, enter the normal task illuminance.
Read the floor
Lay the phone on the floor and read the lux with the built‑in meter. Record the lowest, and optionally the highest for uniformity.
Watch the verdict
The app works out the required minimum and marks each point compliant or below minimum live, with the uniformity ratio.
Generate & send
Sign and generate the PDF, which lists every point, the required and measured lux, the ratio and the overall result.
Common Mistakes to Avoid
- Measuring under the fittings only. The failures hide midway between luminaires and in corners — measure the dark points.
- Leaving daylight in. One shaft of daylight through a glazed exit door can turn a fail into a false pass.
- Measuring at minute one. The standard is about the end of the duration; a bright early reading proves little.
- Wrong area type. A corridor is not an open area. Classify each point correctly or the minimum is wrong.
- Ignoring uniformity. A point can meet the lux minimum and still fail the 40:1 (or 10:1) ratio.
- Meter at waist height. Escape‑route and open‑area figures are floor‑level; measure on the floor.
Before You Issue — Quick Checklist
Frequently Asked Questions
What is an illuminance verification report?
A record of measured emergency lighting light levels compared against the minimums required by BS EN 1838:2013. For each point it records the area type, required minimum lux, measured lux, uniformity ratio and whether it complies. It provides photometric evidence for a completion, site compliance or periodic certificate.
What are the minimum emergency lighting lux levels?
Under BS EN 1838: 1 lux along the escape‑route centre line, 0.5 lux across the central band and in open (anti‑panic) areas, and for a high‑risk task area 10% of the normal task illuminance and never less than 15 lux. These are minimums at the end of the rated duration, measured at floor level.
How do I measure emergency lighting illuminance?
Switch off the normal lighting and exclude daylight, then measure the lux at floor level at each relevant point. The worst case is at the end of the rated duration when the batteries are nearly discharged. Record the lowest reading at each point, and optionally the highest in the same area for the uniformity ratio.
What is the uniformity ratio in emergency lighting?
The ratio of the highest to the lowest illuminance in an area. BS EN 1838 requires it to be no worse than 40:1 along escape routes and in open areas, and no worse than 10:1 in high‑risk task areas, so there are no dark patches between luminaires.
Can I measure emergency lighting lux with my phone?
Lux Meter Pro includes a calibrated light meter, so you can lay the phone on the floor and take the reading directly into the Illuminance Verification Report. The app works out the required minimum for the area type and marks each point compliant or below minimum as you go.
Is measuring lux required, or is a visual check enough?
For routine periodic testing a visual check that the route is adequately lit is often accepted. Measured lux is required or strongly advisable where there is no authenticated design data, when verifying an existing installation, after alterations, or whenever there is doubt the design levels are met — and measured readings are an accepted form of photometric evidence in BS 5266‑1.
Measure and Certify Lux Levels In One App
Lux Meter Pro is a calibrated light meter and a certification tool — read the lux on the floor, and the Illuminance Verification Report works out the BS EN 1838 minimum and marks each point pass or fail as you go. Generate a clean PDF and email it to the client. The same report is in our Cert It web app too.