MV cable must be shielded?

Isaiah

Senior Member
Location
Baton Rouge
Seems I recall a section that states any power cable rated over 2000V must be shielded but cant seem to find it. Can someone please comment?
Thanks in advance
Isaiah
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Engineer
Excellent - thanks petersonra
This reference does not apply to conductors inside of equipment, like switchgear. Unshielded conductors are commonly used to connect internal power, instrument, and control transformers However the general 'electrician' would not be installing them in the field.
 

Isaiah

Senior Member
Location
Baton Rouge
This reference does not apply to conductors inside of equipment, like switchgear. Unshielded conductors are commonly used to connect internal power, instrument, and control transformers However the general 'electrician' would not be installing them in the field.
Thanks Jim. Would you happen to know the standard that talks to this, i.e. wiring inside switchgear. Or is this in NEC?
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Engineer
Thanks Jim. Would you happen to know the standard that talks to this, i.e. wiring inside switchgear. Or is this in NEC?
The NEC does not apply to internal 'factory' wiring. Many people might refer you to 90,2(A) and 110.3(B), but I would go directly to 300.1(B).
 

paulengr

Senior Member
The “factory wiring” is hidden inside the “Listed” rule...you are working with Listed assemblies. Factory built equipment is Listed. As in it passes requirements for BIL which is effectively a simulated lightning strike.

One of the problems at MV is that most of the standards for instance are IEEE/ANSI standards and are for distribution (NESC) use which is outside NEC scope. There is one UL standard but it’s sort of a catch all so you need to recognize that MV equipment is mostly distribution or used by organizations not bound by NEC (mining, ship yards, military, utilities). It frequently is not Listed and it always even under NEC is restricted in terms of access to qualified workers only. There is always a tool required for access whether it’s a ladder, key, screwdriver, or wrench, or there are shutters and disconnects that remove power and make it inaccessible as the door is opened.
 
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