NEC Article 310.6 and application with primary transfomer cabeling

[buckeyemurphy]

I cannot find any reference in the NEC that excludes the connection between a close coupled disconnect switch and a transfomer with primary voltage larger than 2000V. I cannot recall seeing any field installations that have shielded cable connections between the disconnect and the transformer, but I was wondering if this was spelled out in the code anywhere?

 

[davidbeach]

If the switch and transformer are both part of a listed assembly, the code requirement would not apply to the internal wiring.

 

[buckeyemurphy]

Does this refer to section 310.1 when it states that these requirements of section 310 do not apply to conductors that form and integral part of equipment?

 

[cuky2000]

Beware that the NEC primary focus is not in voltage above 2000 V.
Regardless the application, insulated conductors are typically manufactured as follow:

NON-SHIELDED:
• 2000 V for insulated single non-metallic covered cables in UG installation
• 5000 V for OH installation with separated single conductor in air.
• 5000 V for UG or OH installations with assembled conductors with a common overall jacket.

SHIELDED: Above 5000 V.

 

[davidbeach]

There is a lot of unshielded conductor used within 15kV class switchgear. Yes, 310.1 would apply as does the second paragraph of 90.7.

 

[tulum]

In switchgear I believe the 15kV cable is actual space out to allow for a "bare bus" type rating through free air.

There are no manfactures of unsheilded cable as far as I know.

 

[alehman]

Switchgear manufacturers sometimes use 'covered' wire, which has a rubber jacket intended only to prevent faults in the event of accidental contact.

http://okonite.com/Product_Catalog/section6/sheet4.html