Electrical Ducts

[sshamasi1990]

NEC provide ampacities for three insulated conductors, rated 0 through 2000 Volts in underground electrical ducts in table B.310.15(B)(2)(6). The ampacities are for 1, 3 and 6 electrical ducts. How would you determine the ampacities for 7 electrical ducts or 8 electrical ducts, each carrying one cable with 3 conductors at RHO=60, LF=50?

 

[ron]

You have to perform Neher McGrath Calcs. I use Ampcalc, but ETAP and others do it too.