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

[Patrick Finnegan]

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.

Pat
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