Over here, when a lightbulb goes off, it does so because it's power has been cut. It is in off mode.
The other meaning that can be attached to other things.....dynamite, bombs etc., is to infer that it has exploded.
What part of off means on, when referring to a lightbulb, unless an idiot has wired its switch the wrong way round?
If you mean that someone has a lightbulb come on, or is having what we call a lightbulb moment, please say so, rather than just writing "when off ", whatever the hell that means.
Does A2K have an interpreter service of which you could avail yourself?