ANSI/NEMA C82.77-6-2023 PDF

The purpose of this standard is to recommend a method of quantifying the visibility of temporal light artifacts (TLA) and to recommend initial, broad application-dependent limits on TLA.

The photometric recommendations and measurement methods are applicable to any lighting equipment (e.g., luminaires, light engines, self-ballasted lamps, drivers, and sensors) with any control system. Specific recommendations and measurement methods for phase-cut control dimmers are included.

This standard applies to visibility of TLA to human observers in applications with limited speeds of motion, such as an office environment. It does not address interference with optical equipment such as cameras and bar-code scanners. It does not address the potential for adverse stroboscopic effect in high-speed environments, such as machine shops.

This standard addresses two effects: flicker (observable at frequencies below about 80 Hz), and stroboscopic effect (observable at frequencies up to about 2 kHz, and even higher if modulation depth is large and high-speed motion is present). In stroboscopic effect, the object moves and the eye is still. In the case of phantom array effect, the object being viewed is still, and the eye moves. Phantom array effect is out of scope of this standard.

The metrics to be used for evaluation of TLA, for a light source, are:
a. Pst, to quantify flicker (frequencies below 80 Hz)
b. SVM, to quantify stroboscopic effect (typically frequencies between 80 and 2000 Hz)

The metric to be used to evaluate the potential for inducing TLA, for a phase-cut dimmer, is jitter.