I have seen -48V done both ways - black as 0V and red as 0V. Red as 0V seems to be more common.
Both are confusing if you are not familiar and I usually resort to getting out a voltmeter to check before connecting anything. Black as -48V is bad if you expect black to be at ground and not have any potential. Red is bad as ground if your crew thinks hooking up batteries means they should connect the + side of the battery to the red wire. Makes for a big boom when you hook the -48V rectifier to the +48V battery. Don’t ask how I know that. I like Orange for -48V myself but of course we didn’t consistently use that - so I still have to get my voltmeter out. Mark > On Jun 29, 2015, at 5:35 PM, Adam Moffett <dmmoff...@gmail.com> wrote: > > in DC I've been doing red for positive and black for negative for my entire > life.....read that in a book when I was in elementary school. > > Do they do things differently with -48? It just occurred to me that a > different color code would be an easy way to alert people that they're seeing > positive ground. >
