Metallic Shield of Medium or High Voltage Shielded Conducto

[Postigo]

Hi, how is determine the size of the grounding conductor for putting the Metallic Shield of Medium or High Voltage Shielded Conductors, Stress Cones, to ground? I have been looking in the NEC 2005, and the only I have found is in Article 310.6 ? Shielding, that said that they have to ?be grounded through an effective grounding path meeting the requirements of 250.4(A)(5) or 250.4(B)(4).? In this article the only said is that;



?shall be installed in a manner that creates a permanent, low-impedance circuit facilitating the operation of the overcurrent device or ???



This really doesn?t make much sense. What overcurrent device?



This is not the primary purpose of grounding the shield.



Is there in the code another place that deal with this? Is there another source for this? Like NESC 2002, IEEE 80, IEEE 142????..etc,



If, let me know.





Thanks;



Ra?l A. Postigo

Mayag?ez, Puerto Rico

USA



:?:

 

[bdarnell]

Is this is a multi-grounded system ? Do you have a neutral conductor running with your MV conductors ?

Typically, in a multi-grounded distribution system, the neutral, cable shields, transformer case and X0 are all grounded to a driven electrode at the transformer pad. I'm speaking of an underground distribution system, of course. You might have something different in your application.

 

[Postigo]

This a 3 phase delta without a neutral but there is grounding conductor runig with the MV from the pole (in a raiser pole) then underground to the substation.

But my question is if thre are a rule for the size of the grounding conductors of the sress cones?

 

[don_resqcapt19]

I don't think there is a code rule that applies to the shield grounding conductor. A conductor with a cross sectional area equal to that of the shield itself should be fine.
Don