Non Shielded cables up to 2400v

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ssweat

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2005 Code Book states that cables installed over 2400 v must be shielded. Non-shielded cabled will now be printed 2400v and not 5000v as has been the standard forever.
1. Is this being enforced by code inspectors?
2. Where 4160 was the shielded standard, why was this 2400v change made?
3. Do Code inspectors care about UL thinks and UL inability to react to Code changes with cable manufacturers.
 
Re: Non Shielded cables up to 2400v

I do see serious impact on existing installations where cable replacement may be necessary and termination space for stress cones is limited.

Had UL seen serious problems with it, their rep on CMP6 should have maintained their original opposition during the Proposal stage at the Comment stage. That single negative vote would have killed the original Proposal since IEEE swung their vote to a negative.
 
Re: Non Shielded cables up to 2400v

This proposal was submitted by the TCC the substantiation was

Substantiation:
This proposal is intended to enhance safety. Commercial specifiers have installed 5-kV to 8-kV cable without shielding because such
construction is allowed by the NEC. Many cable manufacturers specifically recommend against non shielded cable above 2-kV, but are
hesitant to insist on shielding because of concern of having the customer source another supplier. However, several cable manufacturers
have experienced arcing problems in customer installations where the cable conductors are separated outside of the outer sheath. These
arcing instances are numerous, and present a possible safety hazard.
Note: See proposal for modifications to Table 310.63.
Also see photograph and letter from Southwire Company which I have provided.
Note: Supporting material is available for review at NFPA Headquarters.


Edit for spelling

Charlie

[ March 09, 2005, 12:38 PM: Message edited by: cpal ]
 
Re: Non Shielded cables up to 2400v

Originally posted by charlie:
Bob, I think the intent was to sell a lot more copper. :mad:
Click to expand...
I was somewhat ambivalent; for "new" work most of my clients tend to specify shielded cables for 4160V and above anyway. But a few older plants used 5/8kV cables on 4160V ungrounded or high impedance grounded systems and, truthfully, they left ground faults uncleared too long. They were having serious long-term voltage stress problems.

Their Operations wouldn't let them shutdown a circuit for repair unless it failed or until scheduled turn-around - even if they had a spare. They had gotten so remiss in timely repairs that they were afraid that if they shutdown for repair they wouldn't have a "spare" available if the second circuit failed.

Several motor termination boxes simply wouldn't have room to terminate a stress cone.

All I could do was attempt to influence the IEEE vote; Bruce and I have served on several tech committees together.
 
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