I guess you didn’t watch the anime. (Serial Experiments Lain)

In the story, some secret agency is running an experiment on her. Her family is fake, she gets custom, powerful hardware slipped to her by strangers, etc. So it is reasonable to assume that in that scenario that bedroom would actually be wired for that much electrical draw.

I think that’s what the added power pole seen in the window is for, they just tap straight off that