Great, but electricity is really quite dangerous and eating into the safety margins seems very short sighted. I've seen all kinds of horrors in home wiring. This might seem fine in a world where all wiring is completely up to standard, but in the real world it's done by busy electricians or clueless DIYers. The safety margins are there because in a real installation something will probably be not quite right. It's very common to find wires buried in insulation (the insulation installers don't know or care about electricity), wrong size breakers in use, old/worn out breakers/RCDs, loose connections, the list goes on...