4160V Feeders

[Sean Perry]

Hello,

I am managing a job that involves the installation of MV feeders throughout a large (old) airfield thats been turned into a park. These feeders are going from small substations to multiple buildings. The plans call for 4-4/0 5kV conductors for each feeder..and thats it. This is a 3-P setup, but it does not specify the neutral or ground. To my understanding, in this situation you would typically run 3 conductors with CN's and then a LV ground. So I'm a little confused as to what should be run for these feeders. The spec for the 5kV cables is MV-105 EPR. I'm not sure what the purpose of the 4th cable is for. Can somebody help me understand the purpose of that 4th conductor, and why it doesn't call for a ground cable?

Thanks,

 

[petersonra]

if it is really a feeder it will need an equipment grounding conductor run with each circuit.

 

[electrofelon]

Your details are scant. What are the transformer configurations? Is there a MV neutral? If it is a MGN system per 250.184(C) then there would not be an EGC. Otherwise, see 250.190(C)

 

[Jraef]

MV feeders are often run as ungrounded delta, no neutral. Can’t tell from your limited info, but that would not be unusual.

 

[kwired]

MV feeders are often run as ungrounded delta, no neutral. Can’t tell from your limited info, but that would not be unusual.

Don't you still need to run an equipment grounding conductor even though you have an ungrounded system? I know you do with lower voltage systems.

 

[Jraef]

Don't you still need to run an equipment grounding conductor even though you have an ungrounded system? I know you do with lower voltage systems.

The 4th conductor.