OT: UPS buying suggestion

Erich Dollansky erich at alogt.com
Fri Oct 18 04:05:02 UTC 2013


On Thu, 17 Oct 2013 15:15:35 +0200
Ralf Mardorf <ralf.mardorf at alice-dsl.net> wrote:

> On Thu, 2013-10-17 at 15:10 +0200, Ralf Mardorf wrote:
> > On Thu, 2013-10-17 at 13:15 +0100, Frank Leonhardt wrote:
> > > On 17/10/2013 07:51, Ralf Mardorf wrote:
> > > > On Thu, 2013-10-17 at 14:29 +0800, Erich Dollansky wrote:
> > > >
> > > Most RCCB (aka ELCB, RCD) work (hereabouts anyway) work with 
> > > counter-wound coils on the input and output of the supply such
> > > that he magnetic field is neutral if the current is the same. If
> > > it goes out of balance, it trips the switch. Normally 30mA
> > > difference is the rule. They don't have a value, as such. I heard
> > > that only 10mA is needed to interrupt your heart, but I've also
> > > heard 100mA. They're all potentially dangerous. It depends on the
> > > route taken by the current passes through your body
> Correct, I've got professional literature about this issue, but I'm to
> lazy top take a look now. Don't trust a RCCB!
the individual resistance of the person getting in contact is much more
important. I know a person who gets an electric shock touching 12V DC
because his body's electrical resistance is very low. Most people I
know and tested have a resitance between two fingers of 20 to 30kOhm.
On the other extreme, I have more than 1MOhm.

> > As mentioned before, a workshop in addition must use an isolating
> > transformer, by this galvanic isolation you can't get an electric

I highly doubt this. Only larger workshops have a transformer. They are
getting 20kV and more supplied and need the transformer for a different


More information about the freebsd-questions mailing list