http://www.hea.de/impulse/i/ausgabe/1_09/fachbeitrag2.jpg

These are typical drywall boxes (sectional view), except the top one with extra wiring space is rather rare.

Renosteinke, have you worked here as you know so much?
I have by the way never experienced a whole box pulled out of the wall even when tripping over a plugged cable. It can happen that you pull the outlet itself out though, if its not properly secured to the box.

Last edited by andey; 02/02/14 03:13 PM.