Flicker: the pulsing you cannot see but that affects you
The eye does not perceive it, but the brain does. Invisible flicker causes visual fatigue, headaches and, in specific cases, a dangerous stroboscopic effect around machinery.
- Reference standard
- IEEE 1789 · EN 61000-3-3 (PstLM, SVM)
- Scale
- PstLM ≤ 1 · SVM ≤ 0,4 (a partir de 2024)
- Where it applies
- Obligatorio en la UE desde sept. 2021
- How it is measured
- Con el driver real y a distintos niveles de regulación
Flicker is the rapid oscillation of luminous flux. In LED it depends almost entirely on the driver: a cheap driver lets mains ripple through and the light oscillates at twice the mains frequency (100 Hz in Europe). Below about 90 Hz the flicker can be perceived; above that it is invisible, yet the visual system still responds to it.
The EU has regulated it since September 2021 in the Ecodesign Regulation with two parameters: PstLM ≤ 1 (visible low-frequency flicker) and SVM ≤ 0.4 (stroboscopic effect), the latter mandatory from 2024. Any product legally sold in Europe must comply, but ask for the figure: not everyone declares it.
The dangerous case is the stroboscopic effect: under flickering light, a rotating part can appear stationary or to turn slowly. In a workshop, a warehouse with machinery or an industrial kitchen this is a genuine safety risk, not a nuisance.
The practical trap: many products comply at full power but get worse when dimmed. If the project uses DALI or wireless control, demand the flicker figure at 10 % output, not only at 100 %, because that is where cheap drivers give themselves away.
- Ask for PstLM and SVM on the datasheet; if they are not published, there is reason to doubt.
- Quick site test: film the luminaire with a phone in slow motion; banding reveals flicker.
- Demand the figure in dimmed position too, not only at 100 %.
- In spaces with rotating machinery, SVM is not optional: it is safety.
