You might be surprised by the different opinions surrounding the use of Romex cables in conduits. It makes you wonder where the truth lies. Some people are convinced that the authorities prohibit this practice. But others say otherwise. Which is it? What is the truth?
Can You Run Romex In Conduit?
You can run Romex in conduit because
- Conduits were created to defend vulnerable wires from destructive and corrosive components that can harm them. Therefore, if you use a conduit, it will extend the life of the wire.
- Installing Romex in a dangerous setting will cost you a lot of money because the cables will keep deteriorating, forcing you to buy replacements. You are better off investing in a conduit. Even if the pipe is expensive, you will save money in the long run.
This is not the question most people ask. They understand that Romex can survive in a conduit. But they are more interested in finding out whether the practice makes sense.
As every professional electrician will tell you, just because you can do something doesn’t mean you should. Romex is unique because people use it everywhere.
They call most nonmetallic wires they encounter ‘Romex.’ In fact, some people think that ‘Romex’ is a type of wire, but that is not true. Romex is actually a brand. People call these cables ‘Romex’ because a company called ‘Romex’ makes them.
Why does that matter? Most local codes won’t mention Romex because it is not a type of wire, hence the confusion. People don’t know whether or not a conduit is appropriate for Romex because Romex is not a standard cable whose use is regulated in the industry.
It is no different from any other brand. Therefore, you cannot expect the NEC to mention Romex and its relationship with conduits specifically. That being said, homeowners cannot ignore this brand because you find Romex wires everywhere.
People love them because of their flexibility and competitive prices. If you’ve never seen a Romex wire, this is what you can expect:
1). The cable has three wires, namely: a negative wire (white), a positive wire (black), and a bare copper wire.
2). Romex covers these wires in paper to protect them. Additionally, if the wires overheat, they won’t stick to one another. But you can remove the paper with relative ease.
3). The paper is not the only protective element. You will find all three conductors inside a PVC plastic jacket that repels basic threats.
4). The sheath comes in various colors. The color will tell you the gauge and amp rating.
For instance, 14AWG conductors that accommodate 15A circuits have a white sheath, whereas a 10AWG wire that can run 30A circuits has an orange jacket.
If you’re paying attention, the information above will raise a vital question. If Romex has an outer jacket, what is the point of running it through a conduit? That is a good question with three answers:
1). The Law
First of all, you don’t have to run Romex in conduit. The law doesn’t have any specific information about Romex and conduits.
In other words, you have some wiggle room. Most electrical codes do not mandate the use of conduits where Romex is concerned. Additionally, they don’t prohibit this practice. Therefore, you can do what you want, to an extent.
If you trust the outer sheath, you can ignore conduits. If you don’t trust the outer sheath, you should use a pipe.
2). Safety
There’s a reason why many contractors prefer to use a conduit. PVC sheath cannot protect the bare copper wire in a Romex cable. The other two conductors are more or less okay.
But the copper conductor is vulnerable. If you leave the Romex cable in a dangerous location, elements such as oil and gas could infiltrate the jacket, harming the ground wire. Therefore, you should use a conduit to protect the wire.
You don’t have to use a conduit with every wire. Metal-clad cables are strong enough to survive rugged conditions without wearing out. Otherwise, conduits are the way to go.
3). Location
Where do you want to install the Romex? Any nonmetallic wire you wish to install outdoors should run through a weather-resistant conduit. This is also true for underground cables because they have to contend with dangers like pests and humidity.
Indoor wires are safer. Homeowners can run Romex through a conduit indoors. The NEC doesn’t prohibit this practice. But you don’t have to.
Ultimately, you should make an informed decision. Conduits are annoying because running a wire through these devices is not easy. However, a pipe will extend the durability of your lines. They will last so much longer than exposed wires.
But Why do People Hate Running Romex In Conduit?
Some people hate the idea of running Romex through a conduit. They have several reasons to dislike the practice, including:
1). Complicated Process
Using conduits is not easy. If you don’t have any experience with the technology, it may take you an age to pull Romex through a tube, especially if you selected the wrong conduit.
For many contractors, the practice is not worth the hassle. They prefer to work with bare wires.
2). Durability
A conduit is supposed to protect the cable. But if you don’t know what you’re doing, you may do the opposite. You can damage the jacket in your efforts to pull the Romex through the pipe. Professional electricians may experiment with conduits, but newcomers will avoid them altogether.
3). Size Limitations
The conduit will limit the number of wires you can use. After all, you have to adhere to several regulations that govern the number of cables you can pull through a conduit.
For instance, you have to make do with the 31 percent allowable fill for some wires. This will force you to invest in larger conduits. What if those conduits cannot fit in the available space? As you can see, pipes are not as beneficial as people think.
4) Heat
People like conduits because they are strong enough to repel destructive elements. But that same strength will encourage the tube to trap the heat the cable generates.
If temperatures skyrocket because of the conduit, the heat may destroy the conductors, especially if the ambient temperature is already relatively high.
5). Wet Location
You can’t use certain conduits in wet locations because they will harm the cables once they rust.
This shows you that conduits are not perfect. Don’t forget: you have to buy them. If you only budgeted for the wires, the cost of the pipes may strain your financial situation.
Also, many homeowners already hate the many rules the NEC and their local codes are forcing them to follow. Therefore, they have no interest in doing anything the law hasn’t mandated.
What Does The NEC Say About It? Is It Legal?
The NEC doesn’t prohibit consumers from running Romex through a conduit. It is also worth noting that the NEC wants consumers to run nonmetallic wires through tubes to protect them from dangerous elements. Therefore, if you have a stripped, exposed Romex cable in an outdoor setting, you should run it through a conduit.
As you now know, the NEC doesn’t say anything specific about Romex and conduits because Romex is a brand, not a standard wiring type.
But you can still use the information the NEC has provided about conduits to make decisions about your Romex cables and whether or not it makes sense to use a pipe.
I suggest you go a step further and consult local inspectors. A local inspector knows the local code, and they can tell you what it says about Romex and conduits. The local code supersedes the NEC.
How To Run Romex Through Conduit?
- You pull the wires through the pipe. Admittedly, anyone that has ever performed this task will tell you that it is easier said than done.
- Wires tend to resist this process, either because they are too flexible or because the pipe is too small. Use lubricant. Apply the gel or soap to the cable to make it slick. It will encounter less resistance as it traverses the conduit.
But the absence of resistance won’t necessarily make this process less of a nightmare. After all, you can’t just push the wire into the conduit.
What if it bends and gets tangled?
You can apply the string method. Again, this is precisely what it sounds like.
- Tie a string to a rod and push it through the pipe. Connect the lower end of the string to the cable and use the upper end to pull it through.
The string method is a homemade solution. If you can find one, buy a conduit mouse. They are specifically designed to guide wires through conduits. Don’t limit yourself to these options.
You can use any technique that works for you, including the fish tape method. But if you don’t have any experience with conduits, this process will still take a long time.
How Many Romex Wires in Conduit?
You can add 12 14AWG wires to a ½-inch EMT conduit. On the other hand, you can fit as many as 38 10AWG wires in a 1 ½-inch EMT conduit.
| Size and Type of Conduit | 14 AWG Wire | 12 AWG Wire | 10 AWG Wire | 8 AWG Wire |
| 1/2-inch EMT | 12 | 9 | 5 | 3 |
| 3/4-inch EMT | 22 | 16 | 10 | 6 |
| 1-inch EMT | 35 | 26 | 16 | 9 |
| 1 1/2-inch EMT | 84 | 61 | 38 | 22 |
| 1/2-inch PVC—Sch 40 | 11 | 8 | 5 | 3 |
| 3/4-inch PVC—Sch 40 | 21 | 15 | 9 | 5 |
| 1-inch PVC—Sch 40 | 34 | 25 | 15 | 9 |
| 1 1/2-inch PVC—Sch 40 | 82 | 59 | 37 | 21 |
| 1/2-inch PVC—Sch 80 | 9 | 6 | 4 | 2 |
| 3/4-inch PVC—Sch 80 | 17 | 12 | 7 | 4 |
| 1-inch PVC—Sch 80 | 28 | 20 | 13 | 7 |
| 1 1/2-inch PVC—Sch 80 | 70 | 51 | 32 | 18 |
| 1/2-inch FMC | 13 | 9 | 6 | 3 |
| 3/4-inch FMC | 22 | 16 | 10 | 6 |
| 1-inch FMC | 33 | 24 | 15 | 9 |
Let’s check the size of the conduit for different wire sizes.
| Wire Size | Conduit Size |
| 4/3 | 1 – 1 ¼ |
| 6/3 | ¾ – 1 ¼ |
| 8/3 | ½ – 1 |
| 10/2 | 3/4 |
| 10/3 | ½ |
| 12/2 | 1 |
| 12-3 | 1 |
| 14-3 | 1 |
Don’t take the information in this table at face value because it will change depending on the type of conduit and the number of wires.
If I Run it Through Conduit, What Kind of Romex Wire Should I Use?
You can find a conduit for every kind of Romex you want to use. Consult an electrician if you have questions. They will match your Romex to an appropriate pipe.
Best Conduit Types for Romex
- Metal Conduit
Rigid metal conduits are strong. They are perfect for rugged locations. Intermediate metal is lighter and thinner. You can use it in places that require rigid metal conduits. Liquid flexible metal conduits are typically found around AC units.
- PVC Conduit
Rigid PVC pipes are great conduits because they can survive corrosive environments. They have a lot in common with plastic plumbing pipes.
- Flex Conduit
Flex conduits have a spiral construction that enhances their flexibility. They are easy to manipulate.
- Liquid Tight
You find this conduit in outdoor equipment. Some manufacturers pair it with a plastic coating.
How Long Will Romex Last Underground?
You can’t just bury regular Romex cables because the moisture will invade the conductors. It could easily last 20 or 30 years. But it may deteriorate before that. You are better off using a conduit. The wires will last longer.
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