Comment by userbinator

DC is also much harder to switch than AC; the latter has zero-crossings which tend to extinguish any arcs that form, but DC will just keep going. Look at the DC vs AC ratings on switches and you'll see a huge difference.

A nice demonstration:

https://www.youtube.com/watch?v=Zez2r1RPpWY

A more detailed explanation: https://www.youtube.com/watch?v=mQpzwR7wLeo