Ripple control is a legal form of controlled voltage fluctuation within the power grid. This allows energy suppliers to remotely shut off large power consuming electronics (i.e. heat pumps, electrical heatings stoves). These grid disturbances are usually a short term occurance at a predefine time. They can vary based on location and supplier.
The classification and verification of light sources has been made under homegenious conditions. The power source has been stable and free of disruptions die to a reference voltage source. Those conditions are not always granted in reality, since power sources are usually exposed to several interference factors. These factors often have a negative impact upon the lighting sources electronics which can result in occasional flickering. Therefore it cannot be precluded that even certified lighting sources are compromosied by certain outside factors.