EN 61000-3-3 "Electromagnetic compatibility, Limitation of voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for equipment with rated current ≤ 16 A per phase" contains definitions which prevent mains voltage from varying too drastically at equipment connection points due to device load changes.
This serves to avoid impermissible interference of other consumers connected to the same mains supply. For luminaires with incandescent lamps of up to 1,000 W input power, luminaires with discharge lamps of up to 600 W input power as well as LED luminaires of up to 200 W input power, no further measurements are required by this norm, since compliance with the thresholds is assumed. In lighting installations, power can generally be assumed to be relatively low and constant, and to not generate significant voltage fluctuations or flicker. Professional event lighting (theatre, disco) is an exception, since it features great power and rapid power changes (flashing light in discos).