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Old 07-15-02, 04:18 PM
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I would like to run 4 cables of 12/2 with ground which is 12 wires in all , into a 2 inch conduit. The cables are already there I just want to put them into a conduit . Is 2 inch big enough. thanks
 
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Old 07-15-02, 05:40 PM
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You should be getting a response from one of the electrical pro's, but seems to me I've seen similar questions and there was something of a no-no about running romex inside conduit.

Pro's?
 
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Old 07-15-02, 06:26 PM
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The national code permits romex in conduit for protection from damage. See the site below for an example calculation.
http://www.homewiringandmore.com/hom...lenmb2emt.html
 
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Old 07-16-02, 05:37 AM
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My mistake. I searched old posts and found the one I was recalling. The poster was being told not to, but the replies cleared up the question. Thanks, Ron.
 
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Old 07-16-02, 04:20 PM
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I believe it was John Nelson who raised a question as to whether conduit fill should be calculated in short sections of conduit for use as a sleeve or protection. I have researched his thoughts and believe that While the 40% fill limitations found in the table and examples for over two conductors in a raceway would indeed not apply to fill calculations of conduit containing romex for sleeving that is not a complete conduit application.

However the calculations for conduit fill would still have to be done even for short section as per rule 9 of the Tables and example in chapter 9 of the NEC. The calculations would not use the table limiting to 40% fill as per the table requries but the calculation would still have to be done only using 100% fill per rule 9 of that same Chapter 9 tables and examples. The fill would still have to calculate a flat romex cable as a round cable only the 100% fill limit would be used instead of the normal 40% fill limit of that area of square inch inside that conduit.

Now also don't forget that TAble 310.15.B.6 would still apply requiring ampacity deration for any conduit containing more than three current carrying conductors. If I remember right you would have to reduce a 20 amp rated breaker to a 15 amp rated breaker while using 12 awg copper Romex in a conduit sleeve if that conduit contained more than 9 current carrying conductors.

Hope this helps

Wg
 
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Old 07-17-02, 08:26 AM
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Let's try and clear things here. The 2" conduit, how long is it???

And as for WG's response,wow, you confused the he** out of me and I teach this stuff. If we are talking conduit then you will use the table for over two conductors, that part you got right. When it comes to anything that is not considered a conduit such as a nipple then you will use the table and you will use 60% fill calculations. The 100% is there so that you can come up with the 60% fill. Nipples are 24" or less in length. If you look at the table 1 notes they will tell you that you use 60%for fill and that the derating factors of 310-15b2a that you reference need not apply in this instance. The fill refers to the cross-sectional area of the pipe, in essence you may only fill a nipple to 60% of it's cross-sectional area and you don't need to derate anything.
 
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Old 07-17-02, 08:43 AM
Sparksone42
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Forgot to mention this as I was so confused by an that answer!
Why even perform a calculation??? Turn to Annex C Table C10 since all of the conductors are of the same size and this table will tell you that you can install 99 #12 THHN conductors in a 2 inch pipe. No calculation necessary!!
Again this will depend on whether this is an actual conduit and not just a sleeve for protection. Also, the jacket of a romex has to count for something, we have not even taken this into account!
My opinion: go ahead and do it even if it is a conduit by definition. Even taking into account for the outer jacket I am sure that you still fall within the code. It will be like pulling a phone wire through a sewer pipe. One tip though get yourself a bottle of pulling soap from your local hardware or home supply store, pulling plastic on plastic is no easy task!! DO NOT USE DETERGENT SOAP this will degrade the insulation of the cables.
Good luck!!!
 
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Old 07-17-02, 02:55 PM
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Sparkone42, I suspect a lot would be cleared up in what I was saying if I had provided the rule that I was referring to concerning multiconductor cables. Try the following Notes to the tables in Chapter 9.

COPIED SECTION OF NEC;

NEC 2002 Chapter 9 NOTES TO TABLES;

Note 9;

(9) A multiconductor cable of two or more conductors shall be treated as a single conductor for calculating percentage conduit fill area. For cables that have elliptical cross sections, the cross-sectional area calculation shall be based on using the major diameter of the ellipse as a circle diameter.


Hope this helps clear things up;

Wg
 
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Old 07-17-02, 06:21 PM
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While the discussion continues over who can provide the most unconfusing answer, let me just answer this with an unqualified [SIZE=5]YES!![/SIZE] 2" conduit is big enough!

You cannot use annex C because joe4h is using NM cable, not THHN, and NM cable is not covered by any tables. But we don't need the tables -- the calculation is easy. 12/2 has a wide diameter of 1/2". Computing the cross-sectional area as required by chapter 9 for multiconductor cables, four of them add up to less than 0.8 square inches. 40% of a 2" conduit is well over this, no matter what type of conduit is being used. And the 8 conductors only requires a derating to 70% of 30 amps, so a 20-amp breaker can still be used.

The short, uncomplicated answer is [SIZE=3]yes[/SIZE].

This answer does not depend on how long the conduit is, what type the conduit is, or any of the other details discussed in this thread. And no ampacity derating is necessary either.
 
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Old 07-22-02, 05:52 PM
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Thank you john for a straight answer. Joe 4h
 
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