Tips on Avoiding Accidental Emergency Power Off Disconnects

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You spend thousands if not millions of dollars to design and build a data center to ensure continuous uptime, including implementing safety procedures and training programs for people working on site.  You purchase backup power components like N+1 UPS modules, diesel generators, and implement dual power solutions to create redundant power sources to improve your uptime.  And then in an instant, with the single push of a button the entire data center is shut down.

In NEC terms, you have experienced a disconnect.

That button, better known as an Emergency Power Off (EPO), offers several important functions.

• Protect fire and emergency personnel from electrocution when fighting fires.
• De-energize all electrical equipment during a fire.
• Turn off all ventilation, cooling equipment and close fire dampers to contain a fire and ensure proper concentration of clean fire suppressant systems.
• Shut down a data centers equipment during

Unfortunately with a disconnect studies suggest that your company will experienced nearly $300,000 in financial costs.  (Based on averages for accidental/human error outages).

Emergency Power Off - a common problem

A while back I was reading a study sponsored by Emerson Network Power and conducted by the Ponemon Institute on Data Center Outages and I found the results quite surprising, especially the statistics on Accidental EPO/Human Error.  The study, surveyed 453 individuals in U.S. organizations who have responsibility for data center operations, found that 95% of the respondents reported an unplanned outage during the prior 24 month period.  Of those experiencing unplanned outages, 51% reported at least one outage the result of Accidental EPO/Human Error.  Because Accidental EPO/Human Error often represents preventable events, data centers should establish rules and procedures to deal with EPO’s before they happen.

Tip #1

Label the EPO button

One of the best things you can do is clearly label what the emergency power off button is, and why it shouldn't be pushed outside of emergencies.  Make sure the EPO signage is posted in all the languages that could possibly be spoken in the data center.

Tip #2

Cover the EPO button

You don’t want an EPO button that can be triggered simply by bumping into it.  A hinged plastic cover over the button or recessing the EPO button into the wall will help to prevent accidental activation.

Years ago I doctored up my EPO buttons so that they could not be activated until a safety pin was first pulled.  That way the EPO button could not unintentionally be pushed until the pin was first intentionally pulled, my own version of a “fail safe”.

Some EPO buttons can be armed with alarms that sound when the safety cover has been opened.  People will think twice about the consequences of their actions with an alarm going off around them.

Tip #3


Some businesses have cameras throughout their data centers to monitor activity.  Having a camera cover the EPO button might deter a disgruntled employee.

Tip #4

Secure Access Policies

Have a sign-in policy that requires visitors and vendors to sign-in prior to entering the data center and formally escorting them within the data center will limit the potential for EPO problems.

Tip #5


All individuals with access to the data center, including IT, emergency and security personnel should have a basic understanding of the facility and the purposes and use of the EPO button, including when and why it should be activated.

Tip #6

Install an Emergency Telephone

I also recommend installing a red (indicating emergency use) telephone on the wall by the EPO buttons.  This emergency phone should automatically dial an area in your facility that is manned 24x7, such as a guard station or main master control room.  During an emergency situation you want a person to be able to activate the switch and get in touch with someone immediately.  Every second counts in a mission critical environment, the last thing you want is for a person under stress dialing the wrong number.

Hopefully you will be able to implement most if not all of these inexpensive solutions to limit accidental EPO outages.

Ken Koty

For a copy of the Emerson Network Power study Addressing the Leading Root Causes of Downtime.