EPOs - Good or Evil?

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I am the AHJ for a 'Critical Data Information System', with a requirement to make a decision on whether or not to keep the EPO system in the CER. We are performing an upgrade to go from 50 w/sqft to 100 w/sqft in the CER. With this comes the installation of more PDUs, generators, batteries, etc. The Data Center was built in 2005-6, when it was required to have EPOs in the CER, but the new 2011 NEC makes that an option, if certain criteria are met. Just because we can now remove the EPO, is it a good call?

We can argue that the intent of the NEC is to protect life and property, but that gets into a real gray area for this Data Center. Whose life and property? Those in the Data Center, or those depending on the Data Center to remain operational? What is the real possibility of an accidental activation of the EPO vice a neccessary activation? I have never seen one activated intentionally, but have seen them activated many times inadvertently. The inadvertant operation in this facility could put lives in danger.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I used to work as a security guard in a place that had a data center with an EPO.

They were very nervous that someone would actually hit the button some time.

It was on a 60 second timer that was in a closet down the hall.

The guards were instructed that if the alarm went off to go down to the closet and reset it and then go investigate why it was tripped.

I have never quite understood why a data center would have a risk that an EPO would do anything to resolve anyway, at least nothing that any other place would have that don't have EPOs.
 
That has been my experience. People that own Tier 3 or 4 data centers do not want their systems shut down for any reason, up to and including a fire on the floor. In my many years of dealing with EPOs I have never seen one activated on purpose, but have seen many accidental operations. The new installation techique is to make the EPOs as difficult as possible to activate. Thereby, removing any safety measure provided by the big mushroom button.
 

iwire

Moderator
Staff member
Location
Massachusetts
EPOs have always been optional.

If you wire the room with chapter 3 methods no EPO required


If you want to run more cord and unsupported assemblies as allowed by 64d you need an EPo
 

jumper

Senior Member
Ren: Now listen, Cadet. I've got a job for you. See this button?

Stimpy: This one?

Ren: Don't touch it! It's the History Eraser button, you fool!

Stimpy: So what'll happen?

Ren: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?
 
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brian john

Senior Member
Location
Leesburg, VA
In 35 years of working in and around data centers, I know of no instance where an EPO was used for any beneficial purpose, but I do not have enough toes and fingers to count the accidental EPO activations that caused major disruptions.
 

Strife

Senior Member
In 35 years of working in and around data centers, I know of no instance where an EPO was used for any beneficial purpose, but I do not have enough toes and fingers to count the accidental EPO activations that caused major disruptions.

Something like the FA pull stations? HUH?
I always thought if you're running for your life, the last thing you'll think about is to pull the FA station(even if it's right within your arm reach as you push the door open)
But meanwhile it has a certain fascination with children. I raised 3 of them, I had to keep them tied when we were in a building with pull stations.
 

jumper

Senior Member
Something like the FA pull stations? HUH?
I always thought if you're running for your life, the last thing you'll think about is to pull the FA station(even if it's right within your arm reach as you push the door open)
But meanwhile it has a certain fascination with children. I raised 3 of them, I had to keep them tied when we were in a building with pull stations.

Try working in a college with emergency showers with pull chains outside the science labs, not a month went by that some kid would jerk the chain and drench some other kid. They did not realize that that the flow switch also activated sirens and strobes that could only be stopped with a key switch.
 

Rampage_Rick

Senior Member
I was looking at possibly installing an EPO button in a golf cart charging facility. Basically a shunt-trip breaker and a mushroom switch as a means to de-energize a room full of chargers should the need arise. Project fell through so it never went anywhere.

With regards to IT, it does seem a bit asinine to put so much money into redundant infrastructure for the explicit point of reliability, and then install one button that bypasses everything and dumps it on the floor. I liken it to the 6 disconnect rule. They don't make you kill everything with just one throw of a switch... As many as 6 disconnects in one location can be prudently operated in an emergency. Perhaps they should look at multiple EPO switches, say one for each UPS system?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I was looking at possibly installing an EPO button in a golf cart charging facility. Basically a shunt-trip breaker and a mushroom switch as a means to de-energize a room full of chargers should the need arise. Project fell through so it never went anywhere.

With regards to IT, it does seem a bit asinine to put so much money into redundant infrastructure for the explicit point of reliability, and then install one button that bypasses everything and dumps it on the floor. I liken it to the 6 disconnect rule. They don't make you kill everything with just one throw of a switch... As many as 6 disconnects in one location can be prudently operated in an emergency. Perhaps they should look at multiple EPO switches, say one for each UPS system?

disconnects are not really designed to be used in an emergency.
 
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