Pitch illuminance systems that use standard-frequency ballasts with typical sine wave luminance modulation characteristics will produce a wide range of flicker factor test results. This is due to the variation at test points in the overlapping of luminous flux from different luminaires at different angles. With careful planning, it may be possible to design the luminaire focus points for all areas and planes of the pitch to receive overlapping luminous flux from luminaires at different angles. This may produce substantial improvements and may meet UEFA’s requirements for level B and level C stadiums.
Although the above method may produce substantial improvements, it will not meet the requirements for elite level A stadiums without additional solutions to reduce the luminance modulation. A mixture of electronic or square wave ballasts with standard-frequency sine wave ballasts may produce a flicker factor below 5%. This system will be more successful in larger installations where a greater number of luminaires are available to provide overlapping luminous flux from different angles.
A pitch illuminance system that involves overlapping luminous flux from different angles should use a larger number of flicker factor test points to ensure that the flicker factor values are consistent in all areas. It is recommended that 24 test points are used.
Measures to reduce the flicker factor should not impinge upon the illuminance uniformity of any plane.