How do i install a medicine cabinet on a common wall for a comdo bath?

Im not sure where the plumbing is exactlyHow do i install a medicine cabinet on a common wall for a comdo bath?
There are several ways but since a medicine cabinet tends to be somewhat heavy I would reccomend Toggle bolts...some times referred to as butterfly nuts...they require drilling a larger hole in the wall but are very strongHow do i install a medicine cabinet on a common wall for a comdo bath?
You can get a Gadget that you press against theWall and gives off a Signal, a loud alarm noise when ever there is a Metal Pipe Behind it.There is another one that signals when there is Electric Cabling Behind it I have both of these and you put a couple of Batteries in them to make them work. They are not very Dear cheap in Hardware Stores or Electrical Outlets.