#1 DIY Electric Mistake - Can you use Romex Wire in Conduit? 

I love your content. I would have liked code article from 2020 and 2023 code cycles. I'm not an electician so I dont fully understand everything about electrical or code. But did you consider heat build up? I know thats a thing. Because the wires are jacketed they are rated at a certain amperage and temperature. As the heat builds, so does the resistance, and as the resistance rises so does the heat. I've been told that is a runaway senario, which is why we derate wire fill. Is there a connection between that and electricans being almost unanimously against putting romex in conduit? You would be putting a rated, jacketted product into another jacket which increases heat?

@@MarbleGoblin Hi there great points, I added links above. Thanks!

I read the codes but those are Texas codes and not NEC. Texas codes are cool. But it doesn't really matter either way. I always thought you should be able to run sheathed cable in conduit as long as it didn't fill the conduit over 40%. I retired 12 years ago. Back then the inspectors wouldn't let you do that.

I've considered all of these things over the years and done some of them. What I am disappointed in is you. You probably know when and where and how to run a little Romex in a conduit, but you never gave one example of when, where, and how _you_ do it. Thumbs down.

Honestly, this sends shivers down my back. Happy therefore to say that this side of the pond it is a non-issue since we can't even buy that type of wire here. For outside and underground use we have metal shielded cable, inside it is all single wires running through PVC conduit, meaning you don't have to take down the walls to change the wiring. With respect to the amount of wires running through the conduit there is only one (strict) rule: it may never ever carry wires from more than one fuse. In practice this means that inhouse the vast majority of conduits contain just three 20A rated "THHN" wires (ground, zero and fase) however they may be accompanied by one or more 10A rated wires for switching lights.

100% True that!

but it was completely lacking in inane dad-jokes how can i drink coffee without them?

And he didn't advertise a sponsor 😅

God yes! I'm tired of half hour videos saying something that could be said in 5 minutes or less. Even if the subject is interesting who has the time? Save the long vids for something that requires depth and intricacy. We'd all do better, learn more, and see more creator's work.

Right?

I really appreciate that thank you

Yup. It’s content like this that brings me to RU-vid first. I didn’t have to spend 10 minutes weeding through SEO blog spam before finding the answer. Thanks!

I agree. Great pace. Good info.

"wouldn't have", not "wouldn't of". Where did you go to school?

@@banjohappy I was kinda excited because I knew I worded that wrong. Then I realized youre just a dick and aren't correcting me to teach me. You corrected me to feel smug about youself. I bet your mommy is so proud!

I could have sworn I remember working a Friday evening trying to do a last 25 ft run of wire for some track lighting and was short on wire so I grabbed the Romex saw it said thhn and told my foreman lets just run the Romex without the jacket, it be the most expensive 25 ft run ever but screw it at least we'll be done, and we did so ya I even remember cutting some power cables that were 14 gauge thhn to use as pigtails when I was stationed in Afghanistan.

Yeah, the wire inside NM cable is just THHN, so technically it's no different from using any other THHN. The problem, though, is that the manufacturer simply hasn't certified it for use in that way, so technically you're using it contrary to the manufacturer's instructions, which is a violation of the code, regardless of what type of wire it actually is. Basically, there's nothing inherently unsafe about doing it (provided you were careful about how you cut it out of the sheath, which is another potential concern), but it's just against code due to a technicality in how things are written (so _technically_ you still shouldn't be doing it). (However, if the wires have the correct markings on them, then I seriously doubt anybody would be able to _tell_ that's what you did anyway, so...)

I've never seen lettering on the individual conductors inside NM. I wish they had it

If it says thhn is code approved, no matter what the "experts" tell you. There's a NMC to EMT connector made for that.

Wet location we use XHHW not THHN.

Yeah, like I would take your word or anyone else's on here without written verification.

Well as long as you didn't use those conductors you pulled out of its sheathing inside a conduit, then you should be fine.

The fill ratio has more to do with NFPA regulations than anything else, along with mitigation of unintended damage and destruction of your own work. When you're pulling cable or individual conductors over significant distances, what you're pulling is going to be rubbing up against anything else inside that conduit, causing large amounts of friction, which generates heat. This can, will, and has damaged cables halfway through the run to the point that a fire hazard is created in an non-visible area by way of burning through any and all insulation. Cable pulling lubricant does mitigate this somewhat, however the code on this primarily exists to address this issue.

So romex in conduit in an 120F attic? Electrical advice should be left to licensed electricians.

@@mongo7129 I am one. Obviously, the NEC and NFPA should be consulted prior to starting work on any installation. That being said, there is no reason to be using romex in that application in the first place, and if you did, you're getting fired.

@@RighteousJ Homeowners aren't going to reference the NEC and NFPA, thats why they're watching a stupid youtube video! There in no application where you have to run NM in a conduit...none. Running romex in conduit is like burring the american flag... can you yes...should you no!

@@mongo7129 Agreed. That being said, the electrical code exists for a reason, and the main skill you need to be a licensed electrician is to know how to navigate the NFPA in the first place. That's literally how you pass the written exam - answering a selection of code-related questions in a set amount of time, while having the actual book as your sole reference. Beyond that, you're expected to apply that skill on every job going forward. Being a skilled tradesman can best be explained as performing professional guesswork based on incomplete data provided by those of questionable knowledge. Ultimately, the person doing the installation owns any hazards that result from improper work, and if something I'm being told to do by management doesn't line up with the NFPA, it's my obligation as a professional to refuse to perform the work as described. As far as these sorts of videos are concerned, however: if work was done not to code, regardless of whether or not a permit was pulled or a "professional" did it, then insurance won't pay out. There's a saying in my business: if you think it costs a lot to hire a licensed and qualified electrician, try hiring an unlicensed and unqualified one. This absolutely encompasses hiring yourself if you don't know what you're doing but refuse to admit it.

OK for UF (Direct burial using PVC conduct for protection for outdoor use. Metal conduit below ground is not acceptable because of corrosition

Thank you, came in to point that out. Sleeving cables for protection is definitely allowed.

Came here to say just this, have done this for a dryer outlet and for a receptacle for the washing machine

@@pld8993 NEC 358.10 (2023) "EMT is NOT permitted to enclose underground conductors" I hope you aren't a electrician! While IMC & Rigid is permitted with "corrosion protection", It doesn't last forever, just a lot longer than EMT would.

Kitchen island is another good example. NM inside a sleeve is not embedded in concrete, if some one wants to throw that argument out.

This house sure gone crazy!

@@allkindsofoutdooractivities That's a classic!

The three stooges proved that

@@mistervacation23 😂😂 one of my favorite shorts!!

And even without that sort of monopoly, many times a local jurisdiction is one or two code cycles behind the current one--so sometimes a change in the most recent edition won't be relevant where you are, at least not as far as passing an inspection.

Time for a lawsuit. Gov and company doing kickbacks.

All the multi-family new construction here in the PNW has Romex in the outdoor conduit going from the disconnect to the outdoor unit. I do HVAC and asked an electrician about it, I was informed that the inspectors walk up to a building and see 40 something mini-splits and just sign off on it because they don’t want to inspect them all.

I agree that inspectors might not check, but that doesn’t make it right. Conduit is not guaranteed to be watertight, and neither is NMC. That’s why damp locations are not a good idea. Code regulations are there for many reasons. While some reasons may be lost in antiquity or controversial, they made sense to someone at some time. Humans are very likely to come to poor conclusions individually, which is why groups of experienced reviewers come to consensus on codes. “It won’t be checked” and “everybody does it” are not good excuses.

@@joelperigo7213 Isn't it legal if it just goes to the disconnect mounted on the outside of a wall? From what I was reading NEC approves that every house I ever seen had AC unit used NM wire usually 8/2 to a disconnect. 99% of the homes here in AZ are big units not mini-splits usually 4-5 tons. My home has roof top unit like 99% of homes built before 1990 all of them are using NM wire up through the attic to a disconnect mounted on the stand below the unit. The roof top units are like what most are used to seeing on commercial buildings entire AC unit is in one box. The air is ducted up to the roof makes replacing them simple. Newer homes have split systems big condenser unit on the ground like most other states. Those I see disconnect is mounted to the wall with NM wire passing through the wall.

@@Mike-01234 From what I read, similar debate there to what is discussed in this video. NM is straight through the wall and direct in to the back of the disconnect without passing much daylight seems to be common but might not meet code. In my case, the NM ran unprotected through a block wall, wrapped down and in to the box (3” run behind the box), AND was mounted on a stone facade so not right against a wall. Worse than what may commonly be done, in my opinion.

In the situations I am finding, the NM cable is not just coming out of the wall and going to the disconnect, it is also going through the liquid tight conduit from the disconnect to the outdoor unit. Because this conduit is outside, the interior of the conduit is considered a damp location, and as such, NM cable should never be used in it. I agree that this is not correct, and I am not justifying it. When the company I work for does HVAC installs, we contract out the electrical to a quality company that pulls the proper wire. The problem is with the large companies that do the large multifamily, new constructions, and the lazy inspectors that don’t want to do their job. I am not saying all inspectors are lazy, but I have seen a lot that are lazy, or start questioning me, an HVAC service technician, on if the electrician did their job properly and if a certain disconnect is legal or not.

That doesn't really make sense. You can run romex in spray foam or other insulation. If your wire is getting hot it's overloaded.

Sooner or later, a circuit is going to be overloaded. It's inevitable. A breaker is designed to cut power when a circuit is drawing more amps than it is designed to, and has nothing to do with temp. If you are drawing more than a wire is capable, it's going to heat up. Only when the amps are higher than the breaker will it trip. If the wire is in a confined space(not just a couple of inches of spray foam) it has the potential to melt before the breaker trips. There is a degree of heat dispassionate must be allowed for.

@@jtsather4535 I disagree. You think conduit retains heat better than spray foam? Circuits done correctly are almost never overloaded especially dedicated circuits.

@@sparkyjerred419 That word "Almost" burns down houses. Take every precaution against that which can kill you. Even if it seems over the top. You might save a life.

Just for reference, I've been a sparky for 35 years.

True about DIY'ers who run indoor rated Romex outside in what they think is water tight conduit mostly water tight flex conduit. THHN has to be rated TWHN which means rated for wet environments. Most if not all THHN is rated also for TWHN it's marked right on the wire. NM Romex rated for wet environments is lot more expensive. Most electricians don't like stranded wire since NM Romex is solid wire easier to terminate.

True. Since THHN is rated 90°C dry/75°C wet, if all the terminals are rated 75°C and you wanted to save on wire costs for example, you could take advantage of this and use the 75°column, which would usually be the next size lighter, like 8awg instead of 6awg. Whereas NM-B is limited to the 60° column, no exceptions. It would seem that this situation would mostly occur in commercial wiring particularly given the rising costs of material and labor in this day and age.

Easier to run THHN. Don't run romex.

@@ElectricianMagician That's the way the mill I worked in was wired. It was mostly 480 3 phase but there was 277 Florescent lights along with 110 lights. That's exactly the type wire they used in conduit. I have just a 220 submerged pump 4 '' well with 10 AWG and no 10 AwG ground supplying power to it. I was told since I was using halogen lighting in my shop the wire feeding pump from 30 Amp 220 would be sufficient to run to subpanel box to be put in , feeding from 100amp in service panel, 30 Amp would feed to well just like now Prob have a dozen outlets but only one or two would be used at a time. Then a table saw unknown voltage and amps ( watts) possibly drill press and planer. One running only at a time. Also air compressor. It and pump will come on as necessary. Wire feeding to sub panel is 10 AWG 2 COATED HOTS 10 AWG bare gr. I've got 200 Amp panel with 100 to house and 100 will feed shop.

Hey it's all metal, that's an extra conductor to use!

Bravo! Best comment. rofl

Chicago is crazy with that. Think of how many millions of dollars are wasted by being overly paranoid about NM run bare. The majority of electrical fires (besides extension cords/devices plugged in) happen at the terminations/junctions, not over the length of the unbroken cable itself. We could probably save some houses from flood damage if every water pipe was required to be sheathed in a larger pipe to catch any leaks, but sometimes good enough is enough.

You can thank organized crime aka unions for that. It isn't about safety but about limiting who has skills to run conduit. Any kid can drill holes and pull "Romex" to boxes. But to run EMT or even MC takes more skill that are usually kept to union electrician training.

I believe you can use mc/ac cable in the city of Chicago but there is a limit of 25 feet per run

@@vicktorpatriot1430 Yep, and don't forget billable hours for those union members. Pulling a run of NM from a panel takes a few minutes once the holes are drilled. Cutting conduit, doing any custom bends, then pulling conductors, etc. will take many multiples of that time. And that's in new construction - adding to a circuit with finished walls is now a huge project with conduit $$

Glad it was helpful!

You mean the AC adapter?

This is what I always understood to be true. So the bit about not removing the nm shell is just an issue with the mfr recommended use and not really a fire hazard?

I used to work in a wire mill that made both THHN and Romex from thick copper coils and barrels of plastic resins. THHN has one additional coating material added (makes it more resistant to the strains of conduit pulls) that is NOT included in the wires placed in Romex (because it's not required there and so would be too expensive to add), so, while nearly identical, they are not the same, and aren't intended to be run without the paper and outer sheathing

The wires in NM isn't *labeled* as THHN, so running it bare in conduit isn't code-compliant. You need the outer jacket, which has the listing...

@@blairmurri8741 So conduit doesn't cut it, but plastic and paper does? I don't see your logic. Also the N in THHN is the nylon jacket you speak of. Google "what type of wire is in romex"

@@southsko my time working the factory floor was over 25 years ago, I left that industry when people started paying me to write software full-time, and google is a lousy arbitrar of the truthfulness of any given "factoid". Where it relates to safe practices, I prefer the defer to the Code / local laws. But you do you.

You're prior installations are certainly passing the test of time. To answer your specific question the cable you want is UF (which stands for Underground Feeder) and is manufactured to be buried directly in the ground, you can put it in conduit if you want the extra mechanical protection. Every Home Depot, Lowes what have you, that I've ever seen carries it, as always extra $$$ compared to the normal stuff.

@@stuglenn1112 Many thanks for the helpful reply.

There is NO reason to do that. It is MUCH easier just to buy wire and run that through the conduit. You can just get Direct Burial Cable instead.

Ideally UF (Direct burial Romex) in PVC conduit since it is approved. I don't believe standard Romex can be used because the plastic may breakdown over time when exposed to water & contaminates in water.

​@@guytech7310- It's not really a plastics issue, (tho THWN is the right choice for underground installs) it's the paper-based protective wrapper inside the NM jacket can absorb, retain, and wick water the length of cable until it encounters a nicked wire jacket and shorts, or corrodes connectors. Yeah, more a problem in St. Petersburg or Seattle than Reno or Scottsdale, but rain happens!😢

@@KevinSmith-ys3mh Its the material as non UF Romex is not water rated. Look it up.

Apparently some manufactuers do use marked inner wire jackets, some don't. You have to strip back and look for it, probably the cheaper import stuff wont.

There can be differences. It depends on the province in which you will be doing the work. You need to look in the CSA and possibly the ESA for appropriate codes. FWIW…I’m a EE from the US and the company I work for does a lot of equipment installations in Canada.

@@jbponzi1 I often end up spending more time reading comments than watching the video because of all the good information people share. Often things are similar enough that the core concepts are the same at least. The E.F. Knight “Electrical Code Simplified” books are a great reference for Canada. I’m an Engineer too.

@@AndrewMoizer awesome! Howdy do from your next door neighbor 👋 Sorry you have to deal with some of your codes. They can be frustrating for those of us next door. Especially the inspections and the variances we experience. Thankfully, I started a UL508A program here about 15 years ago. That’s helped us a lot.

@@chrisd_man2156 Why? Why is it "dangerous"? And how is it different? If the individual conductors are properly marked (as to size, type, manufacturer data, etc.) on their outer insulations, just as individual conductors pulled off of a roll, what's the difference? Are you saying that the "Southwire" company (for example) makes two different types of conductors, one for spooling on to a roll, and a different one to put into NM or MC? That just wouldn't make economic sense, from a manufacturing perspective. I'd veture to bet that YOU couldn't tell any difference, if you looked at two conduit-runs of wire, with one from a "roll" of THHN/THWN, and one from an NM or MC cable. And what about MC cable? Can the individual conductors in an MC be removed from their metal sheath and pulled into an EMT conduit, for example? How would you (or anyone) know the difference? Now... I'm not saying it's the best practice, nor is it very economical, but it's FAR from "dangerous", and will get one by in a pinch. Lighten-up Francis...

I wouldn't touch it. It's done and won't be a problem. The only issue is that the water will soak into the paper in the Romex.. but who cares? it's not hurting anything. It's done.. just leave it alone

You can run UF in exterior schedule 80 PVC risers..

Glad it was helpful!

Yep, I always want to know the "why" behind rules. It helps me to remember the rule, otherwise it just seems arbitrary.