I toured The Planet years ago in Dallas and was told by the sales rep
that A+B power was two circuits from the same PDU. :)

I consider A+B power to be two distinct feeds, separate utility
entrances, separate generators, separate UPS', PDU's, etc.  Past that I
consider things like firewall separation, rated chases and such to be
customer specific requirements.

Aaron

On 10/23/2023 9:38 AM, Babak Pasdar wrote:
> Hello,
>
> I wanted to get some feedback as to what is considered standard A/B
> power setup when data centers sell redundant power.  It has always
> been my understanding that A/B power means individually unique and
> preferably alternate path connections to disparate UPS units.
>
> A few months ago, 165 Halsey took us down for several hours. They
> claimed that a UPS failed causing this issue.  Our natural reaction
> was that we have A/B redundant power so a failed UPS on the A circuit
> should not take down the cabinet. Joe the facility manager claimed
> that industry standard A/B power means two circuits to the same UPS,
> which makes no sense to me.
>
> They committed to move us to A/B power with redundant circuits to
> disparate UPS units.  However, we had a multi-hour outage again in
> that site this weekend. At first glance it seems to be the same problem.
>
> We have checked with all of our other data center providers who have
> confirmed A/B power is in fact individually unique connections to
> disparate UPS units. 165 Halsey's definition of what constitutes
> redundant power seems unique. Why would anyone pay extra for a second
> connection to the same UPS?  However, I wanted to get feedback to see
> if I am taking crazy pills here 🙂
>
> None-the-less, we have lost all confidence in this facility.
>
> Best Regards,
>
> Babak