Thanks Ragnar for responding. I second what you wrote.
Just some addition:

Standard flush mount boxes fit 55mm holes and there are different types for drywalls (with hooks) and to be plastered in and different depths for more connectors in the back.
They're also used as junction-box-only with a plastic cover if you have lots of wires. Bigger flush square junction boxes are around too.

Yes we mainly use backstabbing (spring loaded push-in terminals) for junction boxes and outlets/switches.
I know they have mixed reputation in the US, but they're really reliable here and never loosen unlike screws do.
http://www.wago.com/cms/images/Federklemmtechniken_main3.jpg
left: regular for solid wires - right: special type for stranded wires. the orange lever unloads the spring to insert or release the wire.
You can remove a wire from the left one too by twisting it 45 degrees left and right and pulling the wire. after some cycles it will release the wire with a zigzag groove in the copper. If you wanna do it right you have to cut that last 3-5mm off before you wago-connect it again.


The color code is
L1 brown
L2 black
L3 gray
N blue
PE (ground) green-yellow



Last edited by andey; 11/19/12 06:17 PM.