Wiring sizing for 20ft DC connection from the battery cabinet to the UPS

[fandi]

Hello All,
Because of space limitation, the 800KVA UPS will be installed 20ft away from the battery cabinet.
Can I size the wires for this DC connection just like AC using NEC Table 310.16 (NEC 2008 and before) or 310.15 (NEC 2011)?
Thanks.

 

[jumper]

Yes. The table is for AC and DC.

 

[Carultch]

Hello All,
Because of space limitation, the 800KVA UPS will be installed 20ft away from the battery cabinet.
Can I size the wires for this DC connection just like AC using NEC Table 310.16 (NEC 2008 and before) or 310.15 (NEC 2011)?
Thanks.

Ampacity is valid for both AC and DC.
Voltage drop has a specific table in Chapter 9 for each version. I think Table 8 is DC, and Table 9 is AC, if I remember correctly. And for AC, it depends on conduit material.

Voltage drop could be significant, given low nominal operating voltage.

 

[broadgage]

You may need wire much larger than the minimum permitted by code. UPS systems are often very sensitive to voltage drop in the battery circuit, and you may need to limit this to 1%, rather than the commonly accepted figure of 3%.

 

[iwire]

Voltage drop could be significant, given low nominal operating voltage.

Between a UPS of that size and a remote battery cabinet I would expect the voltage to be more than 500 VDC.

But for sure voltage drop could be a factor.