Where I work a previous leccy managed to wire one side of a large heater element to phase L1 and the other side to phase L2, sounds simple but the thryristor module kept throwing a wobbler, after much faffing I realised that L1 was from one substation, and L2 from another, my point being I'm not so sure that the electric board get L1, 2 and 3 the same everywhere.
The pal video system has a different volatge for black, 300mV and also theres a front porch as well as a back porch, the black signal makes sense as the signal is stronger for black with ntsc so s/n is going to be much better, I wonder if it makes tranmission more difficult.
Speaking of building, the local tv transmitter building and the road to it were built by policemen in 1950, as it was originally the radio station for the north west police force, the bbc hijacked it.