Running 3 phase 780s on single phase power (was RE: hams on classiccmp)

Roy J. Tellason rtellason at
Mon Jan 19 14:11:48 CST 2009

On Monday 19 January 2009 02:59:53 pm Patrick Finnegan wrote:
> On Monday 19 January 2009, Roger Holmes wrote:
> > >  But, if you run the same load from three separate single phase
> > > circuits and (worst case) the three circuits are all the same phase,
> > > then the neutral current will be the SUM of all three phase currents. 
> > > That's 3 times what it would be otherwise and runs a serious danger of
> > > melting the neutral and starting a fire.
> >
> > I agree with all but the last bit, because if he's running it from
> > three separate supplies, surely he will have three neutral
> > conductors, so no problem.
> Not if he uses the original pdu and original power cord, which has only
> a single 10AWG neutral conductor.

Ah,  THAT was the missing piece...

Now I understand what the concern is with this stuff!

Not being familiar with these systems,  is that cord hard-wired in to the 
computer end of things?  Hooked to a single connector?  Something like that?

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