Using a Steel Messenger for EGC? & NECvsNESC

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redtail_MH

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I perform engineering design work in petrochemical plants with lots of pole lines. These pole lines have phase cables wrapped around a steel messenger. The voltage of these circuits range from 120V through 13,800V.

My question is can the steel messenger be used as an EGC? The NEC doesn't list messenger as one of the 14 acceptable EGCs, but would the NESC apply in this case? In residential installations, I have noticed utilities using the messengers for EGCs back to the pole transformers. The NESC doesn't say much about EGCs and it doesn't appear that the NESC even requires EGCs. Open wire utility lines don't have EGCs. The small static wire above a utility line is for lightning protection and is not close to having the ampacity required for an EGC. What are the NESC requirements for EGCs?

Thanks in advance for your comments.
 
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redtail,
The messenger on the residential service drop is a circuit conductor. It is ASCR (aluminum, steel reinforced). There is a center steel strand to carry the weight and the outer strands are aluminum to carry the current. For the most part NESC is written for the utilites and they use a multigrounded neutral. For the most part there is not an EGC in these systems. The neutral does both jobs on the line side of the service disconnects. The NEC applies to your installations and you need an EGC that complies with 250.118.
Don
 
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