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13.8 volts in conduit #213321 04/10/14 01:29 PM
Joined: Mar 2003
Posts: 849
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Yoopersup Offline OP
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Question
13800 volt cables in conduit,
Two cables (Feeder in Feeder out).
Can they be run in same conduit if correct
sq inch of fill??
Conduit RSC but could be any type raceway.
Yoopersup

2017 / 2014 NEC & Related Books and Study Guides
Re: 13.8 volts in conduit [Re: Yoopersup] #213322 04/10/14 02:19 PM
Joined: Apr 2002
Posts: 7,227
HotLine1 Offline
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Art 215 seems not to address this in the over 600v sections.

Sounds like a design issue with the info you provided. OCP, conductor sizes, what the 'in' & 'out' are, etc., and time to research may all be needed. Derating may be required.

Scott35 what say you??


John
Re: 13.8 volts in conduit [Re: Yoopersup] #213323 04/10/14 05:07 PM
Joined: Jul 2004
Posts: 9,557
G
gfretwell Offline
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I am sure you are be derating this to 80% (4-6 conductors) but I can't think of a code reason why it would be prohibited.
If one set was service conductors it is a problem.


Greg Fretwell
Re: 13.8 volts in conduit [Re: Yoopersup] #213324 04/10/14 05:11 PM
Joined: Mar 2003
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Yoopersup Offline OP
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310.60 Conductors Rated 2001 to 35,000 Volts.
Derateing HV conductors.
I don't think their done the same as under 600 volts.

Re: 13.8 volts in conduit [Re: Yoopersup] #213325 04/10/14 06:38 PM
Joined: Jul 2004
Posts: 9,557
G
gfretwell Offline
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Watts is watts and that means heat. I bet if you run that formula you will end up being in the same place.

I suppose you should just demand the calculation because there is not a table for 4-6 conductors.
I am just a "pump and pulley" guy and that sort of math makes my head hurt. wink


Greg Fretwell
Re: 13.8 volts in conduit [Re: Yoopersup] #213326 04/10/14 06:55 PM
Joined: Mar 2003
Posts: 849
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Yoopersup Offline OP
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Can you even put more then 3 Phase conductors + ground or Neutral in a single conduit?? I've never seen it Done???
HV ductbanks are derated by the number of conduits in the Ductbank not wires in the conduit.
Figure 310.60 Page 342 NFPA Code handbook.
70-159 NEC 2011

Re: 13.8 volts in conduit [Re: Yoopersup] #213328 04/10/14 09:46 PM
Joined: Jul 2004
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gfretwell Offline
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I am not sure why it would be prohibited but I think you pointed out why it is not attractive.

It sounds like you need engineering to determine ampacity.


Greg Fretwell
Re: 13.8 volts in conduit [Re: Yoopersup] #213329 04/10/14 11:24 PM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline
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Purely hypothetical brain teasers are unworthy.

The better question is: At such power levels and cable sizes, when would it ever be economic to do so?

The swift answer is: Never.


Tesla
Re: 13.8 volts in conduit [Re: Yoopersup] #213330 04/11/14 09:44 AM
Joined: Mar 2003
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Yoopersup Offline OP
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Tesla
Sorry not Hypothetical. Read Field problem.
Three 13.8 Switches single feed, Jumpers in between each (line side).
Load off each switch proposed to run thur same nipple as feed to switch! I don't make this stuff up I run into it!
Power calculations, Fill ect no problem.
Yoopersup

Nuff said.

Re: 13.8 volts in conduit [Re: Yoopersup] #213331 04/11/14 10:39 AM
Joined: Mar 2003
Posts: 849
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Yoopersup Offline OP
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Tesla
Sent you info on the E-mail you listed on here.
Codemanec

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