Electrical conduit is common across many industrial and commercial installations, but how do you know what conduit works best for which situation?
The fact is – it depends on the conditions. Every install is different, so it’s worth knowing how much strength you need, what the environment is (heat, moisture, chemicals), and how many 45 or 90-degree direction changes there are.
It seems like a lot to keep track of, but conduit is crucial to a safe project. With some planning, workers can perform installations faster while ensuring the job holds up years after completion.
Galvanized rigid conduit is a strong, durable, thick-walled steel tubing made using a hot-dip galvanization process to help avoid corrosion. In specific installations, GRC also serves as a grounding material.
Although it provides outstanding protection for electrical wiring, it comes at a cost. GRC is heavy and sometimes difficult to work with, and if workers need to change direction for a bend, they need threaded fittings and bending tools.
Applications: GRC is common in industrial locations and other hazardous areas where corrosion is possible.
Intermediate metal conduit has a thinner wall than GRC but is easier to work with and more cost-effective. It offers strong protection for wire and cable and is often used when GRC might be overkill.
Like GRC, intermediate metal conduit is galvanized to protect against corrosion and may be threaded for faster connections when making bends or terminations.
Applications: IMC is excellent for commercial and residential spaces, including along walls and ceilings and in areas where corrosion poses a risk.
This thin-walled conduit is easy to install, flexible, cost-efficient, and lighter than other types of conduits. EMT still offers corrosion protection, thanks to a hot-dip galvanization process, and its bendability means workers can use hand tools to maneuver it into tight spaces.
One drawback of EMT is that workers need fittings and couplings, like compression fittings and set screws, to connect pieces together.
Applications: Electrical metal tubing is well-suited for commercial and residential low-voltage installations, including wiring and controls. It doesn’t offer much impact resistance, so it’s better to use EMT in aerial or vertical applications attached to a structure.
True to its name, flexible metal conduit is bendable and easy for workers to manipulate. Made from interlocked metal bands, FMC offers good protection and excels in tight areas where the conduit must bend to fit.
Despite being easy to work with, the interlocking bands leave FMC susceptible to moisture if improperly prepped. The bands also have sharp edges, so installers should be careful to avoid damaging wires.
Applications: FMC is great for winding through tight or concealed spaces and near machinery where wires would have been exposed. For more use cases, check your NEC (National Electrical Code) codebook.
Like how a liger combines a lion’s power with a tiger’s swiftness, Liquid-Tight Flexible Metal Conduit combines the flexibility of FMC with a watertight PVC jacket to help it excel in wet environments.
Although Liquid-Tight Conduit bends, the PVC jacket causes it to be more rigid than FMC. However, the jacket makes this conduit suitable for outdoor applications, including spots where excessive sunlight is an issue.
Applications: Liquid-Tight Conduit works well in areas where wires need protection from extensive moisture and splashing water, including boatyards, cranes, and service entrance installs.
Aluminum is less common than steel conduit but has several advantages worth considering.
Unlike heavy steel conduit, lightweight aluminum makes sense for aerial applications like scissor lifts and is easier to move and handle. Like steel, it can be threaded and bent using tools and may serve as a grounding conductor in specific applications.
Though aluminum conduit costs less than its rigid steel counterparts, it’s weaker and may undergo galvanic corrosion if improperly installed.
Applications: The bigger the project, the more savings aluminum conduit provides. The metal also holds up well in areas where salty air is a problem, including coastal regions. Saltwater is corrosive, but aluminum forms aluminum oxide as it corrodes for added protection.
Made from corrugated plastic, ENT is a thin walled, highly flexible PVC conduit that can be bent by hand. ENT is lightweight, easy to install, great for large jobs, and suitable for damp or wet environments because of its corrosion resistance.
Compared to similar metal conduits, ENT is less expensive but capable of protecting wire and cable from abrasions. It is also direct burial rated in some formulations. Other versions of electrical non-metallic tubing are suitable for communications and fiber installations.
Applications: ENT works for internal installations, including residential and commercial applications. Workers can install it outdoors, but it should be used where it won’t be subjected to high temperatures or direct sunlight since both can weaken PVC.
Like ENT, rigid PVC conduit is a lower-cost material compared to metal, but still capable of protecting wires from abrasion and light damage. Unlike ENT, Schedule 80 has a thicker wall and is more difficult to bend, though the thinner Schedule 40 conduit is more flexible.
Fittings and connectors for rigid PVC conduit are low cost and easily let workers make 45 and 90-degree angles. Keep in mind the direction changes may require sweeps for larger arcs. If you have questions, consult your NEC code book or local codes department.
Applications: Rigid PVC conduit has many commercial and residential uses because of its low cost and easy installation, especially along walls and ceilings and for direct burial situations. It also makes sense for some industrial applications because of its corrosion resistance.
Strong, lightweight, and corrosion-resistant, fiberglass conduit uses fiberglass strands combined with epoxy or phenolic (a composite resin) to create a low-friction, flame retardant, low-smoke material suitable for many projects.
Fiberglass conduit is expensive, but it’s a low-weight/high-strength solution with a direct burial rating for some applications. For everything it’s good at, fiberglass sometimes struggles in colder temperatures but outperforms PVC in high-temp areas.
Applications: Fiberglass makes sense where fire safety and protection are critical, thanks to its fire resistance and low smoke production. Fiberglass conduit is also an option where corrosion is a threat, including wastewater treatment facilities, chemical plants, substations, power plants, offshore operations, and telecommunication.
HDPE conduit does some of everything, from housing electrical and telecommunication cables to pushing water and gas or even serving as wall pilings for marine applications.
The plastic used to make HDPE conduit is durable, abrasion, impact, chemical, and corrosion resistant, and is a generally low-cost choice compared to metal products. Additionally, HDPE conduit is flexible and smooth, making pulling cable easier than other types.
Applications: HDPE is a fantastic general-purpose conduit with uses across residential, commercial, and industrial projects. However, it struggles in high-heat situations, with crush protection, and where direct sunlight is an issue.
Regardless of what conduit you choose, look to the NEC code book, local code enforcement, and other electrical professionals whenever questions pop up.
Like wire and cable, not every conduit makes sense for every project. Choosing an overkill conduit when something more cost-effective or less heavy-duty will work can inflate your budget and lengthen installation times. On the other hand, using a conduit with the wrong protection can create fail points, leading to potential hazards.
When in doubt, work with your team and code enforcement to determine your options so you can install your wires confidently!
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