Are you trying to install electrical wires outside? If you consulted a local contractor, they probably encouraged you to run it through a conduit. But are they correct? Tubes are not free. And before you spend your hard-earned money on one, no one will blame you for taking a moment to determine whether these tools are even necessary. The answers in the guide below may surprise you.
Does Outdoor Electrical Wire Need To Be In Conduit?
Not all outdoor electrical wires need conduit. If the wires are rated for outdoor use, you can use them without conduit. But use conduits in any setting that threatens the health of your electrical wire. It prevents wear and tear and extends its lifespan.
1). You Can Use Conduit In Both Interior/Exterior Settings
Do you know what conduits do? You can’t just run a cable through a pipe without understanding the role these tools play. Conduits are defensive devices. They protect the wire from harm.
People associate them with outdoor cables, but you can use conduits in interior settings.
2). Use Conduits In Extreme Conditions
Homeowners associate conduits with outdoor cables because the pipes protect wires from dangerous elements. That includes direct sunlight, pests, pressure, chemicals, etc.
Exterior locations are more dangerous than interior locations because they expose electrical lines to extreme conditions. However, the interior of an unfinished house can present just as many dangers as the exterior.
Simply put, you have to use conduits in any setting that threatens the health of your electrical wires, regardless of whether the location is inside or outside.
3). Check The Legal Considerations
The law has a lot to say about conduits and electrical conductors. Most electrical codes expect consumers to apply conduits to cables in settings with dangerous elements. But some regulations are not as strict and detailed as others.
In other words,
If your local code expects you to run the wire through a conduit, you must obey. But if the local code doesn’t care about pipes in exterior locations, you can do whatever suits your situation.
The NEC scares people because it encourages consumers to use conduits outside. But the NEC is secondary. The local authorities have their own rules. They typically adopt the NEC’s rulings, but they don’t have to. If your local authorities have clauses on conduits contradicting the NEC, prioritize the local code.
4). Cables With Metallic Sheath Don’t Need Conduit
This is the most important consideration. What does the conduit do? It protects the wire from destructive elements. Wires have sheathing that keeps them safe.
Unfortunately, you cannot trust the jacket on a conventional Romex cable to defend the conductors from the extreme conditions you find outside. But what about cables with a metallic sheath? UF cables that resist sunlight.
You can also find electrical cables with unique sheathing that repels everything from water and oil to fire and freezing temperatures.
This tells you that conduits are not always necessary. Check your wire’s documentation. What kinds of protections does it offer? What does the manufacturer say? Can their cable survive in the conditions you have in mind?
If you contact the manufacturer, they will tell you whether or not the conductors in question require a conduit. If the cable can survive without a pipe, don’t waste your hard-earned money buying a conduit. Tubes are not easy to use. Depending on your experience, it may take hours to pull a line through a pipe.
5). Use Conduit Where There Is Human Traffic
What kind of human activity does the setting attract? You don’t want to leave a bare Romex cable in a place where cars have to drive over it every other minute.
Human traffic is just as dangerous. Passersby can cause a nonmetallic wire’s sheathing to wear out if they keep walking on it. If the jacket tears, the exposed wires will electrocute anyone foolish enough to touch them.
Therefore, your decision to use or forego conduits will depend primarily on whether or not you think the cable is at risk outside. If you believe that the cable can survive without a pipe, check the local code.
If the local authorities have nothing to say about outdoor electrical wires in conduits, you can ignore the conduit. Because there are so many nuanced factors to consider before making this decision, you should keep an experienced contractor on hand. Make sure they sign off on every decision you make.
When To Use Conduit For Electrical Wiring – Is It Necessary?
According to NEC, it expects contractors to use conduits if dangerous environmental factors threaten the electrical lines.
You cannot go wrong by following the NEC. If your local code doesn’t care about conduits in exterior settings, don’t be so quick to discard them simply because of the inconveniences they introduce.
Ultimately, they are beneficial. Nonmetallic cables like Romex cannot survive exterior locations without them.
Otherwise, you will spend significant sums of money on repairs and replacements. Keep in mind that some cables are buried beneath concrete slabs. Therefore, repairing or replacing those wires is time-consuming and expensive.
How To Put Electrical Wire In Conduit?
If you’ve ever installed a conduit, you know why people hate them. The process is long and complicated. You have to note the importance of mapping out your route ahead of time, measuring distances and adjusting the pipe’s length accordingly, customizing the conduits to fit the bends, etc.
If you want to run the tubes underground, you have to dig several trenches. Depending on where you live, your local authorities may compel you to apply for permits before you install the pipes.
Some departments want to review and approve your plans before you can execute them
Your local code may also specify the depths to which the conduits must be installed. That doesn’t even account for the soil type and pre-existing plumbing and electrical lines you must avoid.
If it wasn’t clear before, it should be obvious now. You need a licensed electrician to install conduits. Once the pipes are in place, the next challenge is to pull the cables through the tubes.
You can try pushing the conductors through the pipes. But the conductors will resist this process by curling or bunching before reaching the other side.
Unless the lines are sufficiently stiff, you are better off pulling them through. Pushing is unnecessarily difficult. Tie one end of a string to a stick and force it through the tube.
Tie the other end of the string to the cable and pull it through the pipe. The Spruce has pictures of a so-called conduit mouse (or piston). You push it through one end of the tube before attaching a shop vac hose to the other end and turning it on to suck the mouse through the conduit.
If you tied a string to the conduit mouse, they will both emerge from the other end of the pipe. After that, it is a simple matter of connecting the string to the cable and pulling it through the conduit.
But many homeowners have never heard of a conduit mouse, and they wouldn’t know where to find one. The ‘String and Stick’ method is the simplest homemade solution.
It is only ineffective when the pipe is too long, and you can’t find a stick with a matching length.
Forcing one cable through a conduit is not particularly difficult. It will take time if this task is new to you. But if you practice, the process will become less challenging. The same cannot be said for situations where you have to force multiple wires through the pipe.
You should apply caution. This process can destroy the wire, especially where rigid metallic conduits are concerned. Use lubrication on the cables to make things easier.
How Deep To Bury Electrical Wire In Conduit?
- The conduit will determine the depth. For instance, you have to bury rigid metal conduits a minimum of six inches below ground. That figure jumps to 18 inches for PVC conduits.
- You should maintain a depth of 4 inches for metal conduits in concrete slabs.
- If you expect the cables to cross public roads and railways, Hunker wants you to aim for 24 inches below ground.
Let your local contractor make these decisions. They know what the local code says. They can apply its regulations to your situation.
Advantages Of Using Conduit For Electrical Wire
- Conduits are cost-effective. You don’t have to frequently repair the wires in question because the pipe will reduce the rate at which they wear out.
- Conduits can make replacements unnecessary. Electrical wires won’t last forever. But a tube will extend its lifespan. They will last longer because of the additional layer of protection.
- Pipes can improve the cable’s appearance. They are easier to customize than the cable’s sheath
- They will organize your wiring. You can keep multiple cables in the same pipe.
What If I Don’t Use Electrical Wire Through Conduit?
Sunlight, chemicals, oil, and other destructive elements will destroy the sheath of nonmetallic cables, exposing the conductors and creating an electrocution hazard. Eventually, the wires will deteriorate.
Best Conduit For Electrical Wire
- Rigid metal pipes are the strongest. Or, at the very least, they provide the best protection. As such, you can afford to dig a shallow trench.
- Find flexible metal conduits in dry and exposed settings. Their flexibility allows you to install the pipes in constricted spaces.
- PVC conduits resemble plumbing pipes. People love them because you can bend or cut the conduits before gluing them back together at different angles.
- EMTs are perfect for anyone that wants the thinnest and lightest conduits.
What Cable Is Suitable For Outdoor Use In Conduit?
THHN and THWN wires require conduits. You can also run nonmetallic cables through a pipe if you want to use them outside. But that rarely happens because contractors typically install nonmetallic wiring indoors where conduits are unnecessary.
What Does NEC Say About It?
If the cable is not rated for outdoor use, the NEC wants you to run it through a conduit, especially if the location will expose the wire to dangerous environmental conditions.
You don’t have to use a conduit to install a UF cable outside, above, or below ground. But you should take a moment to find out whether the local code agrees with the NEC on this issue.