371.17.G - DC Feeder Wire gauge stepdown for Voltage Drop vs Amperage increase

[salgant]

I am reviewing NEC 2020 and I have a conundrum concerning transitioning wire guages for voltage drop. I know if there is an amperage increase, you need an OCPD to protect your wire, but what about if you are simply changing wire gauges utilizing an approved bonding method in order to meet voltage drop requirements? An example would be where a 250MCM wire is large enough to meet the amperage requirements, but the run is over 1000 ft. long. If you have a cost effective bonding solution, can you go from 250 to 500 to 750 back to a disconnect to counter the voltage drop?

 

[don_resqcapt19]

There is no restriction on changing conductor sizes in a circuit as long as the smallest conductor has an ampacity equal to or greater than the circuit OCPD. Note that this type of installation creates problems with the EGC sizing. See 250.122(B).