I have a commercial set up in a EMS building with a 480/277 fed UPS that has a 208/120 transformer internal to the UPS and then goes to a MLO panel without disconnecting means. Is it required to have a disconnect with this change of voltage and how about the overcurrent protection also? If you need more info let me know.
ups and transformer
- Thread starter lmchenry
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If the panel down stream of the ups is located under the same roof as the ups, a disconnect would not be required. If it is located outdoors or in another building then yes.
If the UPS has a built in secondary OCPD, then that would be all that is needed providing the secondary conductors are sized for the OCPD and the UPS secondary breaker is not larger than the rating of the down stream panels rating. The grounding electrode conductor also needs to be located at the UPS if equiped with OCP.
If the UPS did not come with OCP you'll have to size it occording to there instuctions and it would be located in the down stream panel providing it does not exceed the rating of the panel.
Rick
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
It was a general statement for inside feeder conductors supplying power to inside panelboards. Not an actual article number.
Rick
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