Here's the think about european electricity as far as I see it. Unlike USA or England plugs, the plugs can go into the outlets either way. So if you plug it in this way, the hot is on this side of the plug, if you flip it around, it's on the other side. Kinda like old USA plugs before they had grounds, bi directional I guess you would call it. So..... for like plugging in ballasts, if it buzzes weird, it's plugged in the wrong way, flip the plug over.
This helps nothing with your situation Hydro, because that's what's coming out of the ballast, not out of the wall. Like someone already said black is hot, which goes along with brown. White to blue. And some bulbs I've noticed just do that wierd pulsating thing.