[ale] Considerations Regarding Dual Power Supplies

[Greg Freemyer]

Jeff,

I don't know why ground loops are not typically a big issue with
servers and dual power supplies, but I have RARELY seen anyone worry
about it.

The exception is, I have seen a 30 foot shaft sunk into the ground
near a computer room and a ground line from that directly connected to
a ground distribution panel, which in turn was connected out to the
servers.

Greg

On Mon, Oct 6, 2008 at 3:33 PM,  <hbbs at comcast.net> wrote:
> In audio-land, you have to be mindful of not creating ground loops, i.e, a closed circuit of what should be ground in which EMI (especially 60Hz hum and harmonics) can be induced.
>
> Knowing that, does it cause problems to run power cables from a machine with two power supplies to two different PDUs in a server rack?  Or, is it preferable to connect the two power cables to as close to the same point as possible (i.e., two electrically adjacent outlets in the same PDU)?  Aren't the ground pins in each of the two power supplies going to be connected together inside the machine?  If so, it seems as though having the two grounds form a big loop might bring a lot of hash into the machine through the ground lines.
>
> - Jeff
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