Comment Re:DC power? (Score 1) 239
Here are two reasons why AC is generally better than DC at consumer level:
1: AC arcs are self-extinguishing every half cycle.
Anecedotally: Back in the days when Sydney Australia had 250VDC distributed in industrial areas as well as AC, a DC-powered lamp in a factory blew (filament failure) and started arcing internally. That arc eroded away the glass stem of the bulb, its base, the ceramic bulbholder and most of the flex leading back to the ceiling rose before someone managed to kill the power.
2: Human safety:
DC is more deadly than AC, for pragmatic reasons: If you get attached to a DC power line for any reason, continual muscle contraction will ensure you cannot free yourself. With AC, the pulsating nature of the beast has a greater chance of making you kick yourself free.
I've known people who've been bitten by high voltage DC, AC and RF feeds. The DC guys came off worse than AC, but RF can cook you.
#1 means that every single piece of switching equipment in a DC circuit needs to be derated over its AC counterpart. Take a look at any switch you can lay your hands on and you'll notice that there are AC and DC ratings. This is down to arc resistance, not current carrying capability.