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Size cable for DC

Size cable for DC

Size cable for DC

(OP)
Hi all

Any ideas about sizing a cable for DC?

Thanks

RE: Size cable for DC

DC amps = AC rms amps in terms of cable heating.  This would be conservative, since ac ampacity will actually be slightly less than dc ampacity due to skin effect and higher ac resistance.  

In terms of voltage drop, inductance is not an issue with dc, only resistance.  

As a practical matter, we sized dc circuits just like ac circuits.  Unless you have a lot of it and are trying to economize, that approach should work.  

What voltage and current level?   

David Castor
www.cvoes.com

RE: Size cable for DC

DC sized almost the same as AC like David said.

But since DC loads are often critical loads operating at 125VDC or 48VDC off a battery, voltage drop may be more of an issue.  That breaker trip coil may only draw 4 amps but a #14 awg wire could have too much voltage drop to reliably operate the coil if the breaker is a ways out in the switchyard.

 

RE: Size cable for DC

(OP)
dpc
The voltage is 125VDC.  I think what you said is a good approach!
Thanks!

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