[ale] Considerations Regarding Dual Power Supplies

[Jim Lynch]

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
> _______________________________________________
> Ale mailing list
> Ale at ale.org
> http://mail.ale.org/mailman/listinfo/ale
>
>   
I'm going to hazard a guess that most power supplies are well filtered 
and regulated so even if ground loops exist, they are so far down in the 
noise, they can be ignored, unless the power distribution systems have 
really crappy ground systems.  In the case of other electronic equipment 
like audio amplifiers and transmitters, a ground loop can sometimes be a 
real challenge.   I've been around computer installations for many years 
now and can't ever recall ground loops being a problem or even being 
discussed.

I agree with the others about redundancy being probably a more 
important  consideration.

Jim.