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  1. #1
    SND
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    Default Ot: Ok to run electrical wires in PVC inside a shop?

    I have to run 3 wires to my machines, Says 8/3 Nylon Romex on the wire I have. This is a home shop, kept clean and such. It would be a fairly straight run from the panel or Phase Perfect to the machine along a back wall, then 90 to the machine. So I'm wondering if its OK to run the wires in 1" PVC tubing to keep them somewhat protected, or if I need to use the aluminum armored stuff instead? only reason I think PVC is I got a bunch of the large elbows I want to use up. I know its usually ok for underground. But inside I usually see either armored, or steel tubing. Where I used to be located I had quite a few of the wires not protected with anything, just tucked out of the way and no problem happened.

    thanks.

  2. #2
    motion guru's Avatar
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    NEC does not allow for non UL rated conduit - and Romex is not rated for use in conduit.

    In the event of a mishap / fire - insurance companies are keenly interested in details like this.

  3. #3
    W_Higgins's Avatar
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    Quote Originally Posted by motion guru View Post
    and Romex is not rated for use in conduit

    Just out of curiosity, what is the problem with Romex in conduit (aside from it being obviously more work to install). I had never heard that before.

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    Sea Farmer is offline Titanium
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    When I built my home shop the electrical inspector insisted all exposed wiring be in metal conduit, due to the hazard of swinging long lengths of steel around.

    Don't know if he was enforcing a code provision or his own preference.

    It's not romex either.

    I do a lot of fabrication and am frequently swinging around 8-20 foot pieces of structural steel, and wouldn't care to have unshielded wires on the walls.

  5. #5
    SND
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    This wire had been installed where I used to be located, little more than 2yrs ago. I have 2 lengths of that 8/3 that are a bit over 30' long. At the old location they were just run unprotected from the panel up in the floor joists out of the way and there was only a few feet in the aluminum armored stuff where it dropped back down to a disconnect to feed my PP.From the PP I ran 10/3 romex without any real protection.

    Its the NMD90 wire, apparently good for up to 55amps. Reality is my machines are both only 3HP 3PH and I run only one at the time. Max output of the 10HP PP is 29amps according to the label but I only feed it with a 40amp 1ph breaker. So that wire is quite a bit oversize for the load and not too likely to heat up I think?

    So then... what's the wire to use if running in conduit? Only Single strand stuff of each color? Or should I just run this as it is bare and make sure its just in a safe enough area? I don't swing anything large in here, nothing motorized that could bump into walls, or such.

  6. #6
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    Quote Originally Posted by W_Higgins View Post
    Just out of curiosity, what is the problem with Romex in conduit (aside from it being obviously more work to install). I had never heard that before.

    Heat build up.


    Tom

  7. #7
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    SND, I notice you are in the Great White North eh?

    I am sure you know that Canada has it's own electrical code that is similar to the NEC, but not is not identical.

    To further muddy the water, my 2008 version of the NEC under 334.15 [B] gives type NM cable [romex] requirements for physical protection. Methods include rigid and intermidiate metal conduit, EMT and sch. 80 pvc.

    I have very limited knowledge of the differences between the two codes as I have worked all my adult life under the NEC and have no desire to work in Canada!

    Good luck eh!

  8. #8
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    Where PVC is allowed, it is the gray electrical version and "elbows" don't exist for that, for good reason. You can't pull individual conductors through them, let alone 8/3 Romex.

    Electrical, (gray) PVC uses various radius "sweeps" to turn corners, 45 and 90 readily available. Even with sweeps, most codes limit a "pull" to 180, up to 360 or 2 to 4, 90 sweeps. Varies with conduit diameter and "fill", the volume of conductors in the conduit. More than that compromises the conductors strength and makes pulls impossible without power pulling equipment, which can destroy the conductors as well as "saw" through the PVC.

    Romex is intended to be used in "protected" areas only. 1/2" drywall can provide acceptable, (though dubious) "protection" while Romex is usually not allowed in conduit by most codes. Few codes allow Romex under any circumstances in industrial buildings, other than in finished office spaces.

    Starting from scratch, EMT, (thin wall Electrical Metallic Tubing, not flex) in 10' lengths, standard sweeps and pull junctions such as "LB's", with THHN single conductors would be my choice as to price, ease of installation, protection and acceptability by most codes. A few will demand the threaded "ridgid conduit" that is essentially water pipe, same ID's, OD's and threads, interchangeable.

    If I had the Romex on hand, I'd figure out a way to use it, especially if I wasn't concerned about code inspections but the elbows you have on hand won't work at all to pull Romex through, even if it met code for exposed electrical runs. I'm assuming 8/3 AND ground, (4 conductors, one of them green) for 3 phase.

    Under certain constraints, I have on occasion shoved various types of conductors through standard elbows. It's a pain and the run must be assembled one piece at a time, pull the conductors fully through, fight the elbow down over the conductors with great effort, apply the glue to the joints, (and unavoidably, the conductors), shove another piece of tubing over the conductors etc. This not acceptable under any codes that I've dealt with.

    I have met inspections with Romex in open framing by making U shaped boxes of 1X wood and/or plywood, the center piece lapping the studs for nailing/screwing and the 2 other parts cut to fit between the studs. This is better protection than the acceptable drywall. This "fix" is for minimum routing.

    If it won't ever become a code violation issue, run the Romex tight to the framing members, back against the far side wall covering, on the sides of the studs and just under top plates, (your drill will hate you for that, competing with the nails) and you will provide the Romex with better protection than the "acceptable" open runs between studs, protected only with drywall. This "exposed" Romex could be acceptably protected with pieces of wood.

    Bob
    See what happens when you write too much stuff, everyone beats you to it.

  9. #9
    SND
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    Thanks for the replies.

    The elbows I have are not regular 90 elbows. They are the longer gentle bend and I can pull the cable through it quite easily. I used them when doing my PEX infloor heating system and had extras.

    After doing a little more searching it looks like 12/3 BX would be plenty big to run both of my 3ph machines. Which draw just under 10amps. The wall it would be fastened to is ICF, no wood studs, I can screw to the plastic studs to for supporting the wire. It has to run on the surface but I have 10' ceilings and could run just below that. Everything is already drywalled and painted. Oddly enough I found something on the net saying that if Romex is above 5' from the floor is doesn't need to be protected. I think it was a bit taken from the Canadian code, but its hard to tell sometimes with that stuff on the net. Either way its the wire length where the converter sits on the floor near the panel, and where the power hooks to the machine near the floor that is most likely to get damaged.

    I will look into those 10' sections. I think I may have seen something like that in a school before with junction boxes at each ends. I need to run 110V 1ph plugs along that wall too so it might be really nice for doing that.

  10. #10
    rons is offline Stainless
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    You already have your wire. Just strip the romex outside jacket and use the wires
    as one normally would to run through conduit.

    Save your PVC for something else.

    In my opinion the EMT (thin wall) is not as good as the heavier threaded conduit.
    It's just a little bit more expensive. For the length you are talking about its nothing.

  11. #11
    csaflyn is offline Plastic
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    Here in the states there are other issues that the NEC covers concerning wires in conduit.

    The current carrying capacity of the wire will be reduced due to being in conduit.

    This amount of the reduction will depend on the number of current carrying conductors in the conduit, and the size of the conduit - heat build up issues.

    There may be similar in whatever code you use.

    The same physics apply whether or not codes do.

  12. #12
    Tony Quiring is offline Hot Rolled
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    Default Combine the work and transport

    You stated that you need 120 VAC outlets along the pathway of the large wire.

    Someine else suggested stripping the Romex.

    Romex strips easily as long as it is not the grey outdoor type.

    Determine how many outlets and additional circuits you wish to install and lookup the number and size of conductors you will need to support them, a single white can support opposite phased 120 volt circuits in most codes but most do not use this shortcut.

    If all of the conduit parts are steel then a safety ground is optional in some areas, but I would suggest using some because the connections of thee components could be weak.

    Once your conductor count is determined confirm what size EMT you need to carry those plus a few more.

    If you use DEEP boxes AND your code will allow it you can have your outlet boxes inline with the conduit run and have a simple installation.

    You now have a raceway carrying all of the conductors safely and having the outlets as a bonus.

    If coed will not allow this, then place pull boxes where the outlet go, then using a box connector place your outlet box above/below your raceway and you should be good.

    There are many here who do electrical work for a living, they will give their judgement of this and other ideas, your local building department usually will work with you if you take your drawings to them and ask for how they interpert the code.

    Get some pipe and install your air lines along the same pathway, not much additional work but well worth the investment, your kneew and knuckles will thank you later.

  13. #13
    deltaenterprizes is offline Hot Rolled
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    It is above 7 feet that Romex does not have to be protected because people do not usually walk with their hands in the air so chances of coming in contact with the conductors are slim.
    The PVC would need to be schedule 80 for use above ground.

    Rigid conduit is NOT the same as water pipe. I remember my electrical instructor, Mr Torregano telling us in class "Don't let anybody sell you water pipe for conduit!"
    The interior of conduit is smooth, there i no weld seam and it has straight not tapered threads. Try screwing a water fitting onto a piece of conduit.

  14. #14
    viper is offline Titanium
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    From experience, the NEC code has built in overages much like any engineered design. For smaller runs, you can easily run romex in PVC conduit without concerns of excessive heating. I am not saying it meets NEC code, I am saying it will work without burning up. That is assuming you are using the correct breaker for the wire size.

    I would also agree with removing the wire from the jacket and running as separate conductors. Done this plenty in industrial apps and the conductors will meet NEC code.

    I would NOT recommend leaving the wire exposed if there is any chance of it being bothered. If this is a feeder, certainly put in conduit, if just a branch, you make the call. I doubt I would spring for steel EMT unless there was a good reason. Just a pain for the DIY guy to work with some times.

  15. #15
    mark thomas is offline Titanium
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    Quote Originally Posted by Robert Campbell Jr. View Post
    Where PVC is allowed, it is the gray electrical version and "elbows" don't exist for that, for good reason. You can't pull individual conductors through them, let alone 8/3 Romex.
    Um, the conduit manufacturers call them "elbows":

    http://www.tnb.com/ps/fulltilt/index.cgi?part=UA7AERCAR

    A lot of people say you can't put romex in conduit, but note that no one cited a NEC reference prohibiting this. There's a reason for that.

    There's some other misapprehensions in this thread too, like that rigid conduit is interchangeable with water pipe (not!!), and the vague implication that romex in conduit is automatically a heat risk.

    If you are looking for precise code compliance, you're not likely to find an answer here because there's no Canadian code experts. If you are looking for common sense though, then there is nothing wrong with putting your 8/3 in some PVC "tubing" (your phrase) to give it some protection -- it's better than no protection (your previous install) and it poses no risk, assuming common sense applied.

    That said, I'd always advise doing it right -- use the right materials, do it code compliant. It's usually not much more expensive or that much more hassle, and it reduces the probability of errors, hazards, and future code/inspection issues.

    In your case, BX cable seems the simplest way to go.

  16. #16
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    JST
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    Quote Originally Posted by mark thomas View Post

    In your case, BX cable seems the simplest way to go.
    More precisely, the use of type MC may be the best for easy installation and acceptable protection.

    It is flexible armored cable, WITH a ground wire internal, unlike the old type AC which used the armor as the grounding conductor. NOT the same as flexible conduit, since MC typically uses solid conductors.

    EMT is easy to run and almost always offers sufficient protection from damage

    Rigid metal conduit is acceptable for ALL usages and exposures assuming suitable corrosion protection.

    Non-metallic conduit (PVC) is generally NOT for use where exposed to damage.......

    All the above per US NEC...... Canada may be similar but WILL differ.

  17. #17
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    IMHO: You have the most important area covered... you are not marginally overloading the circuit. If it takes an impact, you'll be there, so you can cut power if the circuit breaker fails to open. I just drywalled over romex in my shop. If I were to encase it for protection, I would just buy electrical conduit. It's pretty cheap stuff. To double check your loading of the circuit, after doing some serious machining for 1/2 hour or hour, check the temperature of the romex going into the breaker box by hand. Mine gets warm when welding, but not hot. If it's uncomfortable to hold, you're pushing it. Declaimer: I ain't no lectrishon

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    Quote Originally Posted by mark thomas View Post
    Um, the conduit manufacturers call them "elbows":

    http://www.tnb.com/ps/fulltilt/index.cgi?part=UA7AERCAR
    Sorry, I thought: "elbows" don't exist...., with the quote marks would be good enough, save words but...? Yes, some companys have begun to use "elbow" in place of the traditional "sweep" for their smaller diameter sweeps. This company hasn't changed the term yet, second bullet under "OUR PRODUCTS", possibly because there is a distinctive difference but....: http://conduittechinc.com/products.php,
    and note, they use they term "sweep" down to 3/4" while "elbow" is never used when referring to the larger diameters of sweeps. Tell the phone or power utility that you intend to run "elbows" in your onsite underground work, and they will correct you, in fact, they will usually add "4' radius is OK" or "10' radius is required" to the word sweep.

    There's some other misapprehensions in this thread too, like that rigid conduit is interchangeable with water pipe (not!!),
    Just the term, "ridgid conduit", would leave some wondering, EMT is ridgid too, so.... I added the descriptive: "essentially water pipe, same ID's, OD's and threads, interchangeable." to compare ridgid conduit to something most people are familiar with. That's the reason that I started the sentence with "essentially". I shouldn't have finished with "interchangeable" because technically that is wrong, though schedule 40 galvanized water pipe has been pressed into service as ridgid conduit innumerable times, with no ill effects, though the electrician who made a quick dash to the hardware store to "get the job done", doesn't point that out to the inspector. Going the other way, conduit for water pipe will dissapoint, hard to make up leak-proof joints with untapered threads.

    SND, if you do decide to strip the conductors from the Romex, electrical supply houses, (and others) carry a small tool, a light gage stamping in a tight U shape that has a hole to guide it over the Romex and a short, sharp tang that pierces then slices the sheathing without fear of damaging the insulation on the indvidal conductors. Makes very quick, safe work of it. "Romex stripper" will send the clerk to the right aisle, though some folks might use a different description.....

    Bob

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    Quote Originally Posted by Robert Campbell Jr. View Post
    SND, if you do decide to strip the conductors from the Romex, electrical supply houses, (and others) carry a small tool, a light gage stamping in a tight U shape that has a hole to guide it over the Romex and a short, sharp tang that pierces then slices the sheathing without fear of damaging the insulation on the indvidal conductors. Makes very quick, safe work of it. "Romex stripper" will send the clerk to the right aisle, though some folks might use a different description.....

    Bob
    Me needs one. Never thunk to look for one... I hate stripping Romex too. I think I hate wiring in general.

  20. #20
    mark thomas is offline Titanium
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    Quote Originally Posted by JST View Post

    Non-metallic conduit (PVC) is generally NOT for use where exposed to damage.......

    All the above per US NEC...... Canada may be similar but WILL differ.
    Not quite. NEC allows PVC where exposed to physical hazards like in a shop, though it does specify schedule 80 (slightly thicker wall than schedule 40).

    It's true that PVC is less common than metal, and some areas/inspectors won't allow PVC, but NEC does.

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