Parallel unshielded 5kV feeder cable

[surfin]

I need to parallel an existing 600ft run of 3 conductor w/gnd 5kV MV-90 500kcmil IAC type cable for an expansion. NEC states 5kV cable needs to be shielded and parallel cables need to be of the same basic design and terminated the same way. Seems shielded cable would have different characteristics. Can shielded cable parallel unshielded? Is there a caveat that would allow me to use unshielded? Could the local AHJ grant a variance in this instance?

 

[waross]

My NEC is out of date, but in my edition the rule that you refer to in your post has a FPN that points out that only the cables that are sharing current are considered paralleled. That is all "A" phase conductors must meet the requirements and all "B" phase conductors must meet the requirements, but the "A" phase conductors do not have to be equal to the "B" phase conductors.
You can distribute the existing "C" phase conductors between "A" phase and "B" phase and add a new "C" phase of a different type of cable. Physically changing the existing cables into an acceptable configuration will be a challenge.
respectfully

 

[surfin]

It is a parallel run to the same termination point. Since the shielded requirement for 5kV is new in 2005 NEC, this is my first (but definitely not the last) encounter with it at our plants. Just a little surprised the NEC didn't address this particular situation.