This is very common, the reason is that the driver of this led lamp is using a very simple capacitor step-down current limiting, rather than a dedicated regular isolated switch type constant current source, although the switch is installed on the fireline, but the 0 line is only 0 potential relative to the fireline, in fact, there will be a certain voltage, or the induction generated by other lines, plus a small power le with extremely high luminous efficiency d do the lamp, after the power supply is turned off, emit fluorescence or induction electricity accumulation to a certain extent and then discharge to form a flicker is logical, to solve this is a little difficult, there are methods, but can not guarantee 100% exclusion: change the double-pole single-throw switch, install a 1:1 isolation transformer, change the isolation switch type constant current source driver... For those who do not know much about electronics, it is still to use it, anyway, it does not consume electricity, it does not affect the life of the lamp, and it is natural to become accustomed to it, as a free lighting.