Why choose 120 volts?

William Pitcock nenolod at systeminplace.net
Thu May 28 11:18:47 CDT 2009

On Tue, 2009-05-26 at 12:39 -0700, Seth Mattinen wrote:
> I have a pure curiosity question for the NANOG crowd here. If you run
> your facility/datacenter/cage/rack on 120 volts, why?

We are using 120V in our colocation spaces.

> I've been running my facility at 208 for years because I can get away
> with lower amperage circuits. I'm curious about the reasons for using
> high-amp 120 volt circuits to drive racks of equipment instead of
> low-amp 208 or 240 volt circuits.

The reason why we are using 120V is because we have pre-existing
equipment (such as PDUs) that only support 120V operation.  I believe
our newer PDUs support 120/208/240, but do not have the time to
investigate that, and we still have a couple of older APC units still in
service.  Our servers don't really care which voltage we provide, most
of the PSUs can determine 120 vs 240 automatically, even.

Also, at least at Equinix Chicago, 120V service was cheaper when we
colocated there.  I do not know if this is the same case at Steadfast in
Chicago, and as far as I know, HE does not offer 208/240 service in
their Fremont-2 facility.  I could be misinformed on that, though.
William Pitcock
SystemInPlace - Simple Hosting Solutions

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