Depends on how clumsy you are.
None. They wait for the electrician to make a mistake and yell at them for doing it wrong.
None. They just blame feminism for the darkness.
Who wants to know
A: Two. One to change it and another one to change it back again.
Doctor: It depends, how old are you Patient: I will be 24 soon. Doctor: Pffff, no you won't.
Depends