how to size the MCCB and cable that feeding UPS unit

[mustafa]

how to size the MCCB and cable that feeding UPS unit,with reference from code

 

[petersonra]

how to size the MCCB and cable that feeding UPS unit,with reference from code

how is a UPS any different than any other branch circuit?

 

[augie47]

(a) determine the load from the nameplate or manufacturer information.*
(b) apply 210.19 or 215.2 to determine ampacity of conductor needed
(c) select conductor with adequate ampacity from Tables in 310 or 400
(d) select proper overcurrent device from 240.4 keeping 110.14 in mind.

* Make sure manufacturer requirements are satisfied (termination limitations, conductor type limitations, etc)

 

[ceb58]

Best to read the mfg. instructions. The Eaton units I install and maintain state #3 wire with an 80 amp breaker for a 12Kw unit.

 

[mustafa]

i have discussion with GE supplier, he advise that i can select the MCCB breaker and the conductor based on ULP panel load not the UPS capacity , considering battery load as well ,noting the UPS is not fully loaded any comments?

 

[petersonra]

i have discussion with GE supplier, he advise that i can select the MCCB breaker and the conductor based on ULP panel load not the UPS capacity , considering battery load as well ,noting the UPS is not fully loaded any comments?

perhaps the electrical code where you are allows this. I think the NEC would require that the conductors feeding the UPS be based on the maximum current the UPS could draw.