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Can romex be put in conduit?

Posted by steve340 (My Page) on
Wed, Dec 27, 06 at 1:00

I have a hot water heater and it is in a unfinished basement. I am running a new 10-2 cable to it from the breaker box and I want to cover the cable from the joist area down to the tank in flex conduit. I will still be using a junction box, just with no splice inside it. Is this ok? Or do I have to use separate wires?


Follow-Up Postings:

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RE: Can romex be put in conduit?

From an electrical standpoint you are fine. You are just protecting the cable as it makes its journey to the water heater. However, the concensus seems to be that you should switch to the appropriate stranded core wire for pulling throught the conduit, particularly if your conduit is long.

Here is a link that might be useful: See this discussion


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RE: Can romex be put in conduit?

Repeatedly the opinion is stated that NM cannot be installed in conduit. But no one cites a code reference to that effect. My search has found no such prohibition in the NEC.


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RE: Can romex be put in conduit?

The raceway articles in the NEC state that cables shall be permitted in the raceway as long as the appropriate cable article does not prohibit the practice. If your cable is non-metallic sheathed cable (commonly called Romex or NM) there is no prohibition against installing it in flexible conduit.

You should probably put a connector on the free end of the cable to prevent abrasion against the sharp edge of the flex.


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RE: Can romex be put in conduit?

My early life was one of poverty, living as the child of a tenant farmer. But things got better eventually. We saved enough to buy our own property. Our financial survival techniques stuck with me. While building my shop in 1981, I had 300 feet of conduit that needed conductors for the lighting system, 30 fluorescent fixtures. The entire building has about 1200 feet of conduit. I was and am the sole occupant and user. My scrap wire pile had lots of used 14-2 romex, the old black mesh covered type. I used the old romex in a proper 1/2" EMT system for the lights. Never a problem with the installation since then. I would not do this on any premises other than my own and then not in my residence.


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RE: Can romex be put in conduit?

The only problem I can see with putting romex in conduit is that it would (should) change the rules on the conduits capacity. For example, I believe codes state that if you're going to have two circuits in conduit, the conduit must be a minimum of 3/4". But if you're going to place two runs of romex, perhaps you should work with a minimum of 1" conduit.


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RE: Can romex be put in conduit?

Which Code article forbids 2 circuits in 1/2" conduit? But it is virtually impossible to get more than one intact NM cable in a 1/2" conduit.


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RE: Can romex be put in conduit?

I see nothing wrong with running romex in flex or rigid conduit although we use stranded core wire as we are often dealing with a four wire system but even then you could use 14/3. On the other hand, it is the pratice of my son, the master electrician, to use stranded core wires in conduit.


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RE: Can romex be put in conduit?

Which Code article forbids 2 circuits in 1/2" conduit? But it is virtually impossible to get more than one intact NM cable in a 1/2" conduit.

Similar to junction boxes, conduit has fill limits. I don't recall what they are, but I thought the net effect was that when you're working with 14 guage wire or larger that fill limits will limit you to one circuit in 1/2" conduit.

If I'm wrong, can someone tell us what fill limits are on common conduit sizes?


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RE: Can romex be put in conduit?

So, do you have a code book?


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RE: Can romex be put in conduit?

So, do you have a code book?

I don't, I'm strictly speaking for experience (and from memory, which can be quite faulty at times) from reviewing some electrical books and participating in forums such as this.


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RE: Can romex be put in conduit?

You should almost never rely on memory when dealing with technical matters. Here's a quote I robbed off of another message board and it definitely applies to the NEC.

It doesnt say what you think it says, nor what you remember it to have said, nor what you were told that it says, and certainly not what you want it to say, and if by chance you are its author, it doesnt say what you intended it to say. Then what does it say? It says what it says. So if you want to know what it says, stop trying to remember what it says, and dont ask anyone else. Go back and read it, and pay attention as though you were reading it for the first time.


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RE: Can romex be put in conduit?

"If I'm wrong, can someone tell us what fill limits are on common conduit sizes?". If my annoyance shows through, that is fine with me. This is one tremendous request from one who has expended no personal effort in the matter. This requires 9 pages 8 1/2" x 11" in the 2005 NEC. It would be a kindness to others who read this forum if the "information" posted about circuits and conduit fill was from an informed perspective. So how about YOU researching the subject and posting your findings?


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RE: Can romex be put in conduit?

"If I'm wrong, can someone tell us what fill limits are on common conduit sizes?". If my annoyance shows through, that is fine with me. This is one tremendous request from one who has expended no personal effort in the matter. This requires 9 pages 8 1/2" x 11" in the 2005 NEC. It would be a kindness to others who read this forum if the "information" posted about circuits and conduit fill was from an informed perspective. So how about YOU researching the subject and posting your findings?

With the exception of a Google search, you are correct, I have done absolutely no research on the subject for which we are talking about. I'm too $@#% cheap to spend the money to buy an NEC book. Even if I had one, I'm too $@#% lazy to read the whole thing.

Now while I might be wrong, it sounds like you are an electrician. If so, you've likely made it your business to study and learn electrical codes so that you can use that knowledge to earn a living. But your attitude seems to suggest that you are offended that someone would have the nerve to ask you to give out your hard learned knowledge for free.

If that indeed is your attitude, I can understand and appreciate it. I've got no complaint. But then what the #@!! are you doing wasting your time in a forum where the (electrically) uneducated seem to come looking for free advice?

If I've got your attitude all wrong, then I don't understand why you're jumping my back over what I though to be a simple question.

If my question is so vague that the answer requires the resuscitation of 9 pages of electrical codes, then just let me know and I'll make my question more precise.

If you don't want to answer the question, then why not just ignore it?

If I'm completely off base, I'd appreciate any constructive criticism that I might be able to use to improve my interpersonal skills (I'm a logical thinker, but with poor communication skills).


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RE: Can romex be put in conduit?

Well said, Hookoodooku. Your communication skills might be better than you think.


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RE: Can romex be put in conduit?

"For example, I believe codes state that if you're going to have two circuits in conduit, the conduit must be a minimum of 3/4"." This sort of false tripe posted earlier is one of the reasons I frequent here. No need for misinformation to become more widespread. Some electrical misinformation is potentially deadly, the above does not fit that category. But for one particular type of 1/2" conduit, one particular type of #14 conductor, and one particular type of circuit on one particular type of power supply, it is possible to have 9 circuits in 1/2" conduit, code complaint. $65.00 will buy a 2005 NEC book.


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RE: Can romex be put in conduit?

Conductor ampacities for most situations are loacted in NEC article 310 and tables 310-16 and 310-17. All ampacities are based on insulation type and not if the conductor is solid or stranded. Watch the fpn notes. Article 240-3(d)Small Conductors- then states "unless specificaly permitted in (e) through (g)of this article the overcurrent protection shall not exceed 15 amps for #14, 20 amps for #12, 30 amps for #10 copper: or 15 amps for #12, and 25 amps for #10 aluminum and copper clad conductors"
Apendix C in the rear of the NEC deals with conduit fill tables. These tables are based on type of conduit, size of wire and type of wire insulation used.
For example if you are using #12 THHN wire you can have 9 seperate conductors in a 1/2" conduit. That could be multiple circuits with neutrals. CAUTION: What you dont want to do is run a circuit with hots only in a conduit without the circuits neutrals included in the conduit and you do not want to run 1 hot wire in a conduit by itsself with out a neatral or the conduit being grounded.
The section addressing the use of romex or NM-B or NM-C ( Non Metalic Sheathed Cable) are in Article 336. Uses permitted and not permitted and protection from physical damage.
Article 300-16(b) deals with Bushings.In the case of running romex through metal conduit it needs an insulating bushing at the open end where the romex enters or leaves the conduit.

Another article everyone should have some information about is Article 250 Grounding. This article will resolve most situations concerning safety and fire prevention. However this article is to be used in conjunction with other articles including conductor ampacity, conduit fill and wiring methods.
I know the book is expensive Aprox $65, and NEC info may not be readily available on the net but the info in it invaluable. Other wise please consult a local licensed electrician or some one who knows and understands the code. Most are more than willing to answer your questions. These types of codes are very important and not ment to be a pain in your butt.


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RE: Can romex be put in conduit?

I'm too $@#% cheap to spend the money to buy an NEC book.

So am I. ;-)

Fortunately, my public library has several copies. I also buy older editions on Ebay for a fraction of the new price. (My area is an edition behind anyway.)


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RE: Can romex be put in conduit?

Forums are great. Anybody can say almost anything. Sometimes good, sometimes questionable.

Let's see what we here have so far.

In this thread we find that the OP has a code specific question about the legality of a particular type of installation.

The first responder is a non-pro who has misinterpreted the difference between NM-B installed in a conduit system vs NM-B installed in conduit for protection, but has essentially given the correct answer in the first part of his post.

The next 2 posts are by folks who, if you frequent this board you would know, are extremely knowledgeable in the trade and with code issues who say it's OK for the OP to proceed as he wanted to.

The next non-pro who responds offers advice which is entirely wrong in his first post then sort of semi-attempts to justify the information with some vague reference to a totally unrelated (box fill) item. Then says "but if I'm wrong, what's the answer". Then, he reveals that the answer he gave really isn't related to anything he read or saw but "thinks" it is something he remembers from somewhere. Then he proceeds to get bent out of shape when it is pointed out that his "experience (and from memory, which can be quite faulty at times) from reviewing some electrical books and participating in forums such as this" is 100% incorrect.

So, now we have an individual who admits no code knowledge getting ticked at someone who does for correctly pointing out that the answer to "what the fill limits are on common conduit sizes" encompasses a bunch of pages in the code book, and the information offered to the first poster is wrong.

Spot on so far?

Electrical work is something that, done wrong, can kill. There are things in the code people often comment about as being stupid that have almost certainly at some point prior to inclusion in the code been responsible for loss of property or life.

Many of the knowledgeable DIYers and pros here recognize that even in spite of suggestions to the contrary sometimes, folks are going to do their own work, or at least attempt it. So, since it isn't an issue of us doing ourselves out of work we might get, we try to help folks get it right. Questions aren't an issue. What IS an issue is trying to answer them when you don't know.

Now, if the question had been posed as "how is conduit fill determined" rather than "well, if my uninformed answer is wrong what IS the right answer?" I suspect a somewhat more reasonable response would have been forthcoming.

To that end, allowable conduit fill is determined by the insulation type, wire size, number of conductors, and type of conduit.

Whether or not you may use the conductors at their full rated capacity is determined by how many are in the conduit, how long the conduit is, how many are considered current carrying, by the temperature of the environment the conduit is in, and whether the conduit is the wiring method or is being used for protection for a wiring method not otherwise required to be installed in conduit.

Whether or not a type of cable or wire is permitted in conduit is determined by the article for that type of wire or cable. If that cable isn't round another code section will tell you how to determine area for that cable for a conduit fill calculation.

I'm here for the same reason Bus is - to help folks that don't know. After a while it becomes an effort to try and keep helping simply because of the way this thread went. If the folks who do know quit posting because they get flamed for getting a little irate at times, the forum becomes a place where people who don't know can load up on information from folks who not only don't know either but are willing to offer the wrong advice and have it go unchallenged.

I've cut way back on the time I spend in DIY forums because of the type of response Bus got. I just quit responding till I"m not ticked about it any more. Over time the recovery has changed from a few minutes to several days sometimes. And based on the responses I see from others I suspect the same thing goes on. Whether or not any one of us quits posting here may not be considered to be a loss, but I can tell you that because a few have quit the answers here have gotten slower and less in depth than they used to be. That's unfortunate because this board hass typically been able to "hash out" issues and not be shut off by moderators. A few of these "airing outs" of subjects have been enlightening to even the pros. Doesn't happen much anymore.

UNK


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RE: Can romex be put in conduit?

itsunclebill (and bus_driver too),

I never got bent out of shape for being told I was wrong. That only happens when I know my facts and someone tries to tell me I'm wrong without substantiating their contradictory claim.

But yes, I did get all bent out of shape. However, the reason I got bent out of shape was because (in summary and from my point of view) I was being told "you are wrong, I know why you are wrong, but I'm not going to tell you why you are wrong, you just need to research it for yourself".

However, reading back over the posting, I believe this thread went the way it did because of my poor communication skills. And even that could likely be boiled down to one word "ASSUME".

I assumed that our discussion was limited to "typical" home wiring and therefore, anyone answering the question would assume distance of less than 100ft, wire sizes involved are limited to 12 and 14 gauge, circuits involved were single phase with 20amp or 15amp limits, and that THHN wire would be used. I assumed that with all these unspoken assumptions that someone familiar with building codes could summarize the complexity of the codes and give us the "rules of thumb" the typical DIY could use. I assumed, I assumed, I assumed.

So I apologize to bus_driver and everyone else following this post that I allowed my assumptions and poor communication skills cause such a mess.

And thank you genr8rs for your response. While you did a pretty good job as seeing through SOME of my assumptions, the length of your post really points out home much I was leaving unspecified.
What I was really looking for is what you pretty much had in your example: ... using #12 THHN wire you can have 9 seperate conductors in a 1/2" conduit ....


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RE: Can romex be put in conduit?

But 9 #12 THHN conductors is not permissible in every type of 1/2" conduit. With some types of conduit, the permissible number of conductors of a certain size is dependent on the type of fitting terminating that conduit- and that limitation may be posted only on the fitting itself- I personally encountered that yesterday. The real problem I had earlier was that this same person was posting on some other threads "answers" that were presented as authoritative, but were only speculation or wishful thinking. That is potentially dangerous where electricity is concerned. If not dangerous in a particular instance, bad information could make electrical work unnecessarily expensive by the use of overly large conduits and conductors.


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RE: Can romex be put in conduit?

... The real problem I had earlier was that this same person was posting on some other threads "answers" that were presented as authoritative, but were only speculation or wishful thinking. ...

I was trying to make nice, but this comment appears directed at me. Under that assumption (so please tell me if my assumption is wrong)...

The only post I can figure you'd be talking about is the recent post regarding isolation transformers, mainly because that's the only thread I recall posting in recently where what I said could have sounded authoritative. (Again, if I'm making a faulty assumption, please let me know).

In that particular thread, I was trying to find a way to explain the concept of an isolation transformer for someone that is uneducated in electricity, not an instruction book or how-to guide.

I have two degrees in electrical engineering, so I can speak with some authority on the subject of electricity. I understand the WHYS of electricity, why conductors need to be a certain size to carry a certain load, why neutral wires in a two phase appliance carry less current than the two hot wires, why circuits need both a neutral AND a ground (even though they both just connect to the same neutral bar in my circuit breaker panel).

But at the same time, I am not an electrician, therefore I haven't been trained in the detailed minutia of all the stuff written in the code.

I will say once again, I welcome constructive criticism. If there is something I've posted in error, please point it out to me.

However, unspecified generalities (i.e. "other threads") only serve as attacks and do nothing constructive to improve this community.


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RE: Can romex be put in conduit?

Is it also okay to fasten about 50' of 1 1/4" non-metallic conduit (gray pvc) to the basement ceiling joists to run 2 or 3 circuits for ceiling lighting and receptacles? The wire used would be 14-2 NM-B W/G 600V ROMEX. The basement is in the process of being finished including the ceiling. I am trying to avoid drilling through 40+ floor joists to bring a wire from the circuit panel to the other side of the basment. The conduit would probably be strapped inside of the metal i-beam that runs the length of the basement.

If yes then is it also okay to cut out about 1/4 of the conduit so that the conduit has an opening from end to end to allow for exit points anywhere along the 50'?

Any other basement techniques to run romex perpendicular to floor joists without having to drill the joists?

Thanks


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RE: Can romex be put in conduit?

You need to protect the romex from physical damage. You can put the romex in PVC and strap the PVC to the floor joists. Can you cut the PVC and open it? Depends if the romex will then be susceptable to damage. You can only answer that question. You can also place a running board along the bottom of the joists and staple the romex to the top of that out of harm's way from any physical damage from below.


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RE: Can romex be put in conduit?

Nail the running board to the bottom of the joists and staple the NM to the exposed face of that board. The plastic ones with two small nails work well in the 3/4" boards.


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RE: Can romex be put in conduit?

What you propose - cutting out conduit - is questionable in terms of code compliance. You'd be modifying an approved product and using it in a manner contrary to its design. This is a highly unorthodox method and would grab the (unwanted) attention of an inspector when you went to sell your house.

It depends on how you're going to finish the ceiling in the cellar, but you should probably just bite the bullet and drill the joists. With anything but a drop ceiling, I think you'll create more problems for yourself by using a running board.

Get yourself a good, sharp 3/4" spade bit and a close quarters drill. Especially in a newer house, the job will go faster than you think.


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RE: Can romex be put in conduit?

"Get yourself a good, sharp 3/4" spade bit and a close quarters drill."

I'd suggest a 3/4" auger self-feeding bit and a heavy duty right angle drill like a Milwaukee Hole Hawg or Dewalt DW124.


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RE: Can romex be put in conduit?

I use 24 inch ships auger bits in a 1/2 inch drill and if it is a long run strap on some drywall stilts and go to work.
If you drill every other joist from the opposite side it is easier to pull through the pair.

The fill limits do not apply to conduit used solely for physical protection of NM.
The fill limits are applicable to a conduit system.
The 2002 NEC added a call out that cables could only vbe used in conduit if approved for the use. Since the NM article was not updated this effectively resticted the use of NM in conduit SYSTEMS, but not for physical protection.
In an unfinished basement it is often convenient to run NM in bored holes in the joists, then use conduit down the wall to boxes. The conduit ends in a cable clamp at the ceiling and in a box fopr a device. This is NOT a conduit system.
My 2005 is at work (even though Virginia is still firmly on the 2002 I need it for other states).


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RE: Can romex be put in conduit?

"I use 24 inch ships auger bits in a 1/2 inch drill and if it is a long run strap on some drywall stilts and go to work.
If you drill every other joist from the opposite side it is easier to pull through the pair."

I use this, don't need stilts, and don't have to drill from both sides because with a short auger every hole is level:


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RE: Can romex be put in conduit?

Tried one. To single purpose to haul around for remodel work.
I have a hole hawg for plumbing runs, and occasionally use it for electric, but having one more thing to load and haul gets to be a real hassle.


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RE: Can romex be put in conduit?

Thanks for all the helpful conversations, people - helps me with my own DIY 1931 knob & tube project


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