Ferroresonance in Primary Cable

[PowerGuy]

Does anyone have experience with installing underground primary (13kV) using three single conduit with one phase per conduit. I am used to seeing three single phase conductors in the same conduit. Won't using singles pose a heating problem?

 

[davidbeach]

One conductor per conduit only poses a heating problem if there is ferrous metal that completely encircles only one or two of the conductors. If there is not a ferrous path around the net current that would result from one or two conductors, there is no heating.

 

[mc5w]

The conduits most definitely need to be nonmetallic such as PVC or concrete. In the case of concrete there cannot be any rebars between the ducts unless the rebars have gaps between them preventing a closed magnetic path.