[c-nsp] OT: DC Power supplies

[Robert Boyle]

At 06:28 PM 7/9/2005, you wrote:
> > That definitely works, though is a bit scary.  It's amazing what you can
> > get away with when there are few electrical codes for DC versus AC :)
>
>Actually, there are DC codes too -- but they usually only apply above
>about 60-70 volts. 48 volts DC is considered "safe" and "low voltage", so
>a lot of the codes don't apply. Not that a few hundred amps of -48vDC
>can't do some pretty serious damage though :-)
>
>For the original poster, I'd personally recommend against running 5 wires
>to 5 circuits to supply one device. You'd be much better off bussing the 5
>circuits together with a copper or brass strap at the fuse panel and
>running one heavy gauge wire from the bus bar to the device. While still a
>hack, it's a bit safer with the bus bar than with 5 seperate wires, and it
>will look more professional too.

I agree 100% That is definitely a better idea than what I said the other 
day after 14 hours of work! :)

-48VDC will easily vaporize metal if a metal part shorts the two terminals. 
When I TIG weld, I'm dealing with only 50-200 Amps at 12-20VDC. Make that 
1000+ amps for a battery bank and lots of bad things can happen if you are 
in the way. Although I concur that many codes may not apply, -48VDC is not 
something to play with and can be very dangerous!

-Robert


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