Can ghosts turn lights on

yes they can they can do anything

Another viewpoint:

It is a human tendency to interpret any mysterious occurrence to supernatural entities. Before we understood that thunder is caused by electrical charges jumping between storm clouds, people explained the frightening sound as giants throwing rocks or as gods driving their chariots. In exactly the same way, if the lights in a building suddenly turn on or off, and you don't think that anyone turned the switch, it is very easy to jump to the conclusion that a ghost is responsible. It is much more likely that some living person turned on the lights, or that there is a "short" or flaw in the electrical system.