Ok, I finally found some decent info on the old german/austrian color coding:
flexes:
P: black
N: grey (can be connected to ground terminal of receptacle with jumper to neutral, TN-C)
G: red
L2, L3: black, blue
fixed wiring: single phase: see flexes
2 switches in one box: feeder black, switch loops grey and red
3 ph: 4w
R,S,T: black, blue, red, neutral (usually only ground) grey, red one can be pink as well, was also commonly used for flexes, this was the most common wiring arrangement.
5w (pretty rare): see flexes.
As you see this system was rather inconsequent, and this is one reason why it was phased out.
However, 4w 3ph systems still have black, brown, blue for phases and y/g for ground.
Anyway, this color code is definitely NOT reliable, even electricians usually took whatever wire color was just handy!
