4160 vac wire

[redwood1957]

working in an older factory with a 4160 feed from the main electrical room to a 600 amp switch then into a 4160/480 transformer (1000kva). Wire is 3-350mcm cu tw and a 4/0 ground wire has a 5000v rating in a 3inc conduit. Does not look like the HV wire I have seen in past
Customer wants to use the wire but increase the tranformer so he can put in a 2000 amp set of switchgear.
Questions
Is this wire allowed and if so what is the ampacity at 4160vac?

 

[weressl]

working in an older factory with a 4160 feed from the main electrical room to a 600 amp switch then into a 4160/480 transformer (1000kva). Wire is 3-350mcm cu tw and a 4/0 ground wire has a 5000v rating in a 3inc conduit. Does not look like the HV wire I have seen in past
Customer wants to use the wire but increase the tranformer so he can put in a 2000 amp set of switchgear.
Questions
Is this wire allowed and if so what is the ampacity at 4160vac?

No it is not suitable for MV wiring.

 

[masterinbama]

Sounds a lot like what we used to see in older water plants. The wire is rated for 5000volts but the problem is it has no integral neutral. I mainly saw it on 2400volt open delta setups. Some people would mistakenly think that since it was rated 5KV you could use it on 4160 systems. If you are getting a delta secondary from it, it will work but that cable is at least 35 years old and should be replaced.

 

[fjrivera]

The wire is not suitable for this voltage. This was changed I think in the 2005 NEC Revision since NEC 2002 had allowed the use of non-shielded cables at 4160V. So, installing non-shielded cables to be operated on a 4160V system is now prohibited.

I read somewhere that one of the concern for this was that when a 5000V non-shielded cable is operated at 4160V, the surface of the cable isn't at zero potential. A standing voltage and current always exists and could under certain conditions be danger to anyone who comes in contact with it.