Romex or Shielded wire in Conduit?

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  #1  
Old 08-18-04, 07:41 PM
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Romex or Shielded wire in Conduit?

Can someone set the record straight for me?
When running PVC for electrical through an outdoor location, is it ok to put 12/2 or 14/2 Romex inside the pipe and then make connections or do you have to use the colored individual wires and run them together(as opposed to having all wires present in 1 piece of romex)?

Glue the pvc or not?

I was told that the heat that would build up on the insulation inside the pipe would cause a fire risk, expecially when using a 220 circuit?

Did the coding on this change recently?
 
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  #2  
Old 08-18-04, 08:08 PM
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The quick answer, NO, you cannot use romex in a conduit. Especially underground. One main reason is that romex is not rated for wet use and an underground conduit is a wet environment. At least in the eyes of the code.

The use of romex in conduit is a contentious issue but the bottom line, and overwhelmingly agred upon answer, is it cannot be used. Lets leave it at that. No, the code has been vague on this for years. They say in 2005 it will be made clearer.

You need to use THHN/THWN rated conductors. Standard building wire.

YES, glue the PVC. Cleaner is not necessary with the proper glue.

I don't see a fire risk unless the circuit is not rated for the amperage used and the breaker is too big. Regardless, it's not being done anyway.

220 volts is a meaningless term as far as draw is concerned. Amperge numbers tell how much a circuit will draw. In fact 220 circuits draw half the amps of a 110 circuit only they do it on two legs instead of one. Many people say "I need to run a 220 circuit, how big should the wire be?" You wont know without the amperage rating.
 
  #3  
Old 08-19-04, 04:47 AM
rlrct
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Speedy Petey,

Take a look at ['99]336-6(b) or ['02]334.15(B). NM underground is definitely a No-No, but you might find those code sections interesting.

Rob
 

Last edited by rlrct; 08-19-04 at 07:15 AM.
  #4  
Old 08-19-04, 05:52 AM
lagunavolts
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romex in conduit

what about UF cable?
 
  #5  
Old 08-19-04, 06:39 AM
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UF cable (also sold as "Romex") is suitable for wet and underground locations. You may sleeve it for short distances for protection where it is exposed. However, using it in complete conduit runs is inadvisable at best. Some say to put UF in a complete conduit run is actually against code, but that always starts a pointless argument so I'm not going there. So in underground conduit, individual THWN wires is the way to go. It is sometimes confusing that THWN is usually sold as THHN, and you have to look closely to notice that it is also rated THWN. If you want to use UF, then skip the conduit (except while above ground and down to the bottom of the trench) and just direct bury it.

PVC conduit must be glued, but the glue must be completely dry before you start to put the wire in. Some people, especially when trying to get UF cable through conduit, try to do one segment at a time, gluing and feeding the cable through as you go, but this is not only a code violation but a recipe for disaster. The glue eats insulation!
 
  #6  
Old 08-19-04, 09:04 AM
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Just to extend this:

1) Conductors in wet locations _must_ be rated for exposure to water. This means THWN conductors or XHHW conductors, or other water rated conductors. This rule applies even if the conductors are in cable or in a conduit. They must be water rated.

2) Most outdoor locations are considered wet locations, again, even if the conductors are enclosed in conduit.

3) NM-B cable, commonly called 'Romex' is _not_ rated for exposure to water. You need to use 'UF-B' cable if you wish to use cable. Just to confuse things, Romex is really a brand name, and you can buy Romex brand UF-B. Just make sure you get the correct stuff.

4) You are _clearly_ permitted to sleeve NM-B or UF-B cable in conduit for mechanical protection. The code does not clearly define how long these sleeves are permitted to be, but common uses are to go from the joists down a wall to a receptacle box in a basement, so inspectors clearly allow 6 or 8 feet of sleeving without problem.

5) The code is unclear as installing cable in conduit for the entire length of a run. The arguments seem to run from 'the code allows it but is not clear' to 'the code doesn't allow it but should'. There is not much argument that you _shouldn't_ do this, though general consensus is that it is often a waste of time and materials.

6) What is clear in the code is the _size_ of conduit required should you happen to run cable in conduit. Code specifies the fraction of the area that the wires in a conduit may occupy. The same section of code requires that if a wire or cable is elliptical in cross section, then you have to calculate its areas as though it were _round_ with the same diameter as the major diameter of the cross section. This means that if you have a bit of UF-B that is 0.625" by 0.25", you have to treat it as a round wire 0.625" in diameter for the purpose of determining conduit size. Given that the wires in this cable are probably 0.15" in diameter, the size of conduit required to pull a cable is often much larger than that required for the individual wires.

-Jon
 
  #7  
Old 08-21-04, 11:41 PM
ironqqq
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hmm... I just ran romex through a flex conduit...

here's a pic. It's not legal?

http://ironchef.info/qqq/remodel3-Au...%20window3.JPG
 
  #8  
Old 08-22-04, 04:59 PM
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Might be legal, might not. There's not enough of your picture to tell. Where does the other end of the flex go? Even if not 100% legal, I wouldn't change it (you weren't going to anyway).
 
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Old 08-22-04, 07:52 PM
ironqqq
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basically, the bottom pic is the other side of a wall where an existing light switch exists.

Pic 1 - Bottom

I tapped into that switch and used metal flex conduit to run it into a ceiling box I installed.

Pic 2 - Ceiling Box

The conduit houses 14/2 romex. The conduit and both boxes are grounded. At the ceiling box, I have another wire that goes into the ceiling. I connected the ceiling romex and conduit wires with wire nuts.

It traverses a aobut 2 feet over to another ceiling box, which I put a low voltage pendent.

Pic 3 - Pendant

In the final picture you see the pendent and the switch plate. That switch used to be a single gang box, but I busted it out, and installed a double gang box for a switch to control the pendent.

That pendent is temporary.. it's an extra I had.. it doesn't match the paint scheme.. but it's there until I can buy another low voltage pendent.

I will replace hte wire inside the conduit if it's not legit.

I'm gonna do another simular project like this in another part of the house, tapping from an the rearside of an outlet, installing a switch in the wall, except I'm gonna use half inch emt coduit and run two sets of wires to control two sets of lights in the ceiling.

thanks.
 
  #10  
Old 08-26-04, 11:06 PM
ironqqq
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I'm gonna make another wire run this weekend, tapping the back of a electrical outlet from a closet outside the house, through flex conduit, and up into the ceiling where I'm gonna put a junction box, and then from the junction box over to where the recessed light housing is going to be installed.

almost identical to the pictures in my previous post, except the furnace closet is now a closet on my patio. The closet is fully finished and has insulation inside the drywall. Has an exterior door and weather stripping, and is permanently covered by the building.

is it acceptable to run Romex all the way from the outlet to the ceiling box?

or will I have to run single wires through the metal flex conduit? and then when I get to my ceiling box, I will make the transition from single wires to romex.

or will I have to use EMT conduit in that closet?
 
  #11  
Old 08-27-04, 11:00 AM
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You need to use a raceway that's acceptable for exposed work, such as EMT. By exposed, I mean outside of the wall or ceiling instead of inside of it. Romex is not acceptable for exposed work. Flexible Metal Conduit can be used, but only up to six feet by code. EMT would be the best/safest route to go anyway, with perhaps a short FMC whip through the ceiling if it's too tight to use the EMT. You can mix FMC with EMT, but you can't mix romex with wires coming from inside a conduit. You need to be able to pull wires from the outlet box to the ceiling box.
 
  #12  
Old 08-27-04, 12:08 PM
ironqqq
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I see.... so i can use FMC, but only up to six feet. I think my run is 8 feet, so I will have to use EMT... but I will measure first.

I need to run 4 wires inside the my conduit (1 ground, 1 neutral, 2 hots) to control 2 lights. can I run a 4 wire romex inside EMT/FMC? or will I have to run 4 singles?

the ceiling box I'm talking about is in this picture.

http://ironchef.info/qqq/ceiling_box.jpg

thanks.
 
  #13  
Old 08-27-04, 12:25 PM
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but only up to six feet by code
Cruizer, can you point me to that six-foot limit in the code? Thanks.
 
  #14  
Old 08-27-04, 04:33 PM
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Originally Posted by John Nelson
Cruizer, can you point me to that six-foot limit in the code? Thanks.

From the 1993 NEC for Flexible Metallic Tubing, Article 349-4. Uses not permited: "(6) in lengths over 6 feet."

Perhaps this restriction has been removed since 1993. If so, I apologize.

4 single wires, Ironqqq.
 
  #15  
Old 08-27-04, 06:30 PM
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Yes, that article is still in today's code for FMT. But I think we dealing with FMC here, which is not so restricted.
 
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Old 08-27-04, 08:46 PM
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Thanks, John, for the clarification. What's the difference between FMT and FMC? Are the walls thicker for the FMC? Do you have any insight as to why FMT is restricted to 6 feet?

ironqqq, so it looks like you could use FMC for the 8-foot length.
 
  #17  
Old 08-28-04, 08:39 AM
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Your code book gives a better description of these two types of conduit than I can. FMT is made of steel, is smoketight and liquidtight and is often used inside ducts. FMC is made of aluminum and is far more common.
 
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