We need to replace the existing non-shielded cable from the 15kV switch to the transformer on a unit substation. NEC 310.10 does not allow non-shielded cable above 5000V phase-to-phase, but I don't think it applies to this situation. I think that we can use non-shielded 5/15kV jumper cable for this installation. Is there anywhere in the Code that would allow this? If not, what are our options? Thanks.
15kV transformer primary cable
- Thread starter egoy
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kingpb
Senior Member
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- SE USA as far as you can go
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- Engineer, Registered
Is there a technical reason why the cable is non-shielded?
What is your reason the NEC section does not apply?
What is your reason the NEC section does not apply?
The non-shielded cable was supplied by the manufacturer of the unit substation and I believe it is used due to space available within the switch and transformer. There is not enough space to terminate a shielded cable and the required bending radius could not be maintained. I don't think the Code applies to this since it is within a factory-assembled piece of equipment. I think the intent of 310.10 is to prohibit the use of unshielded cable for feeders in a medium-voltage distribution system.
kingpb
Senior Member
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- SE USA as far as you can go
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- Engineer, Registered
Read 310.1, it specifically states: "These requirements do
not apply to conductors that form an integral part of equipment,
such as motors, motor controllers, and similar equipment,
or to conductors specifically provided for elsewhere in
this Code."
This is what manufacturer's use to preclude themselves from having to use shielded cable.
not apply to conductors that form an integral part of equipment,
such as motors, motor controllers, and similar equipment,
or to conductors specifically provided for elsewhere in
this Code."
This is what manufacturer's use to preclude themselves from having to use shielded cable.
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