Shunt trip breaker

[Nate Scott]

Explain to me if a shunt trip breaker is needed for a computer room. NEC articles 645.10 & 645.11 deal with a emergency power off system.The fire inspector is trying to get the EPO button to shutdown the UPS system,HVAC system & smoke/fire dampers but there also is a dedicated panel in the data center for security & control reasons that he wants shutdown. Is that where a shunt trip is involved?

 

[quogueelectric]

I have installed many of these epo buttons in computer rooms. I did not design it an ee/architect put it on the prints and I installed it. It puts power on the shunt trip leads of a feeder breaker and trips it off in an emergency.

 

[weressl]

Explain to me if a shunt trip breaker is needed for a computer room. NEC articles 645.10 & 645.11 deal with a emergency power off system.The fire inspector is trying to get the EPO button to shutdown the UPS system,HVAC system & smoke/fire dampers but there also is a dedicated panel in the data center for security & control reasons that he wants shutdown. Is that where a shunt trip is involved?

The objective of an EPO for Fire Fighting purposes is to stop feeding the fire with air - HVAC- and potential source of ignition - arcing electrical fault - and lastly to remove the potential electrocution hazard fro the firefighters. Usually it is accomplished with a shunt trip solenoid that activates the trip plunger of a circuit breaker, opening it and removing the power to the selected devices. In complex systems you may need separate devices for the UPS etc. but it is preferred from the engineering standpoint that they ALL be activated once by a device or devices at each of the multiple entrances.

Security and control devices are seldom a concern for the above stated purposes and indeed in some cases they are essential to aid the firefighters. The AHJ should exempt those from needing to be de-energized.

PS: The shunt trip solenoids have a series contact installed that opens the power flow to the coil after the breaker is opened to de-energize the coil. Otherwise the coil burns and there is your new fire source...... Seen it happen!

 

[ron]

If you are using the leniencies provided by 645 as compared to the regular parts of the code (chapters 1-4 etc), then you need to be able to shut off power to the electronic equipment in the IT Room. Of course there are other requirements too, such as shutting down airflow and disconnecting power from UPS's larger than .75kVA.
If you don't need to use the more relaxed rules found in 645, then you don't need an EPO, just follow the regular parts of the code like any other business occupancy.