Medium Voltage Underground Cable / Smallest Available Size 3

[saladhawks]

I have an application for a 15 kV, 133% EPR Insulation (220 Mil) underground cable that needs to fit in 2" Conduit (1.913" I.D.). I only need an ampacity of 70 Amperes, but have been told by my local Okonite rep. that they will not manf. a medium voltage cable smaller than #2 CU per NEC Table 310.5 (2002 Version). Note that this is an utility application and we are not under obligation to meet NEC requirements. I checked the 2007 NESC and was not able to locate a minimum UG medium voltage cable limit. Does anyone know of a UG cable manufacturer who manufacturers cables smaller than #2 CU?

 

[apowerengr]

salad - even #2 solid al is very small when you look at the mechanical forces at the conductor/connector interface. I would not want to go smaller regardless of ampacity due to the service life of the conductor at this interface. I've seen plenty of #2 AL solid conductors break/burn off in URD applications. Plus, the mfg. make this stuff in "standard" sizes in large lots - you'll pay more to get smaller conductor. You can get a single 220 mil #2 AL in a 2" conduit without a problem.

Are you sure you need 133% or would 175 mil cable work? If it's in conduit you could consider non-jacketed cable which would be smaller in diameter too.

Just some thoughts.