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Wednesday, January 27, 2021
Question:
Greeting Code Friends,
My question is can a copper tape shield of a medium voltage cable be used as an equipment grounding conductor for the feeder? Some engineers say yes, others say no. What say you?
Thanks,
Paul Wise
A
Answer:
Hello Paul,
Thanks for the question. Section 250.190(B)(2) indicates that The metallic insulation shield encircling the current carrying conductors shall be permitted to be used as an equipment grounding conductor, if it is rated for clearing time of ground-fault current protective device operation without
damaging the metallic shield. The metallic tape insulation shield and drain wire insulation shield shall not be used as an equipment grounding conductor for solidly grounded systems. So if this is a solidly grounded system, the answer is no, based on the information in the question. Section 311.44 (in the 2020 NEC) about the uses and purpose of shields in medium voltage cable.