Now I'm curious... in all of the DCs and COs I've worked in - to the best of my knowledge, I haven't personally tested this! - the EPO button does not​ switch to emergency power.  It turns off ALL equipment power in the space - no lights, no klaxons, nothing.  In simpler setups, the EPO is connected to the UPS so anything plugged in to the UPS does dark instantly.  In one DC I'm familiar with, the EPO switch kills all the UPS output and​ uses several relays to kill commercial power at the same time.
In some, the room lights were not covered by the EPO switch, in some they were.  Emergency exit lamps will continue to be lit, as they have internal batteries, and are required by building/fire code.

Is it (somewhat) common for an EPO switch to only disconnect commercial power and leave local redundant power live?  What sort of facilities would have this?

-Adam

Adam Thompson
Consultant, Infrastructure Services
1593169877849
100 - 135 Innovation Drive
Winnipeg, MB, R3T 6A8
(204) 977-6824 or 1-800-430-6404 (MB only)
athompson@merlin.mb.ca
www.merlin.mb.ca
From: NANOG <nanog-bounces+athompson=merlin.mb.ca@nanog.org> on behalf of Jay R. Ashworth <jra@baylink.com>
Sent: September 11, 2021 22:23
To: nanog <nanog@nanog.org>
Subject: Re: Never push the Big Red Button (New York City subway failure)
 
----- Original Message -----
> From: "Sean Donelan" <sean@donelan.com>

> NEW YORK CITY TRANSIT RAIL CONTROL CENTER POWER
> OUTAGE ISSUE ON AUGUST 29, 2021
> Key Findings
> September 8, 2021
>
> https://www.governor.ny.gov/sites/default/files/2021-09/WSP_Key_Findings_Summary-for_release.pdf
>
> Key Findings
> [...]
>
> 3. Based on the electrical equipment log readings and the manufacturer’s
> official assessment, it was determined that the most likely cause of RCC
> shutdown was the “Emergency Power Off” button being manually activated.

I don't even *do* datacenter for a living, and I know that when you hit the
Molly button,

1) A Klaxon goes off in the Data Center -- one that sounds *different* from
the Halon Klaxon, in both cadence and tone (just for a couple bursts), and

2) Yellow rotating beacons turn on, and stay on while you're on Emergency Power.

Yes, real honest-to-ghod *rotating mechanical beacons*, none of this flashing LED
crap.

Clearly, it's important that the use of Emergency Power be annoyingly noticeable.

Cheers,
-- jra
--
Jay R. Ashworth                  Baylink                       jra@baylink.com
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