# 5kv unshielded



## Cow (Jan 16, 2008)

I remember years ago pulling 5kv unshielded wiring into conduit to a 500HP motor.


With that said, I'm not sure what the point would be to keep them from touching each other in a pecker head if they're allowed to be installed in conduit next to each other...?


I remember making them up like any other motor and tried to get some distance between them right at the terminations just so they wouldn't vibrate together and blow up.



On a sidenote, I believe everything has to be shielded now, but I could be wrong.


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## MechanicalDVR (Dec 29, 2007)

Cow said:


> I remember years ago pulling 5kv unshielded wiring into conduit to a 500HP motor.
> 
> 
> With that said, I'm not sure what the point would be to keep them from touching each other in a pecker head if they're allowed to be installed in conduit next to each other...?
> ...


I believe that is correct.


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## frenchelectrican (Mar 15, 2007)

Cow said:


> On a sidenote, I believe everything has to be shielded now, but I could be wrong.


Yuh they did change the requirement few years back so any MV cable have to be shielded.

the exsting one can stay as long it is not damaged in any fashion.


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## Wiresmith (Feb 9, 2013)

factory motor leads are the only thing that's not shielded, field wiring is typical shielded cable. my thought on the separation is i have ran across unshielded cable that was touching the enclosure at a spot and it was tracking there. now i do have to add this was on a capacitor bank for a foundry. but i have also seen even insulators track, usually because of contamination, that's why i am thinking there should maybe be some separation


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## Wiresmith (Feb 9, 2013)

just fyi, 2017 NEC 310.10(E) up to 5kv unshielded MC in industrial, allowed


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## JRaef (Mar 23, 2009)

Unshielded can be used inside of assemblies too, ie in MV switchgear, MCCs, soft starts or VFDs. Allowing them to touch each other is not a concern. Over strapping them and compressing the insulation, thus reducing the dielectric however IS a concern. With shielded cable that’s difficult to do but with unshielded, typically EPR rubber insulation on extra flex cable used inside of gear, the insulation is thick, but soft. Over tightening the straps reduces the thickness and leads to corona discharge.


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## Wiresmith (Feb 9, 2013)

JRaef said:


> Unshielded can be used inside of assemblies too, ie in MV switchgear, MCCs, soft starts or VFDs. Allowing them to touch each other is not a concern. Over strapping them and compressing the insulation, thus reducing the dielectric however IS a concern. With shielded cable that’s difficult to do but with unshielded, typically EPR rubber insulation on extra flex cable used inside of gear, the insulation is thick, but soft. Over tightening the straps reduces the thickness and leads to corona discharge.


i believe you but can field cabinet interior wiring be unshielded or just factory wiring? i can't find it allowed in the code book


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## Southeast Power (Jan 18, 2009)

Uh. MV 90??
You can get it triplexed but, the OP was asking about motor leads.


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## glen1971 (Oct 10, 2012)

When completing motor terminations, if they aren't on stand-offs in a larger junction box, I try and protect the boot from rubbing against the side as best I can. Sometimes I put a piece of rubber inside to help, or change the box out to a larger one...

I've mainly used this style of motor splice boots for medium voltage connections..

https://buy.wesco.com/Motor-Stub-In...Boot-Thermoplastic-Cap/MSCV20/p/78621077335-1


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## Jlarson (Jun 28, 2009)

glen1971 said:


> I try and protect the boot from rubbing against the side as best I can.



I'm a big fan of scraps of conveyor belt for such things. I grab any I can.


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## Moonshot180 (Apr 1, 2012)

The MV motors we maintain are powered at 6.9KV. Hitachi brand motors, and a few Siemens Allis, all of the motor leads are unshielded and are equipped with some sort of dielectric that keeps them somewhat separated...


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## Wiresmith (Feb 9, 2013)

Moonshot180 said:


> The MV motors we maintain are powered at 6.9KV. Hitachi brand motors, and a few Siemens Allis, all of the motor leads are unshielded and are equipped with some sort of dielectric that keeps them somewhat separated...


i've always made an attempt to keep them separated, i think it would help reduce tracking even if just from dirt/contamination on the insulation surface.

thanks


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