Types of Electrical Conduit: A Practical Guide to Choosing the Right Raceway

A conduit run can look simple on a drawing, but the material choice affects nearly every part of the installation: how easily the raceway bends, how well it resists impact and corrosion, whether it can be used in wet or underground locations, how grounding is handled, and how much labor the run takes to install. Electrical conduit is not one interchangeable product. EMT, rigid metal conduit, IMC, PVC, and the flexible raceways all solve different problems.

The practical way to choose conduit is to start with the installation environment and the amount of mechanical protection required, then check the raceway, fittings, conductor type, fill, grounding, and support requirements as one system. The 2026 edition of NFPA 70, the National Electrical Code (NEC), is the current NFPA edition as of September 2026, but jurisdictions adopt NEC editions on different schedules, so the locally adopted code and the authority having jurisdiction still control a specific project.

What Is Electrical Conduit?

Electrical conduit is a raceway used to route and protect insulated conductors. Some conduit systems are rigid, some are flexible, some are metallic, and others are nonmetallic. The raceway may protect wiring from impact, moisture, corrosive conditions, or physical exposure while also creating a defined pathway that makes conductor replacement or additions more manageable.

Conduit sizing is a separate question from conduit type. After the raceway material is chosen, conductor quantity and size still have to comply with fill rules. Lumera’s conduit fill chart and calculation guide covers that calculation in detail.

Electrical Conduit Types at a Glance

1. EMT: Electrical Metallic Tubing

EMT is the familiar thin-wall metal raceway seen throughout commercial buildings, garages, workshops, and exposed utility spaces. It is commonly made from coated steel and is also available in aluminum. Unlike RMC and IMC, EMT is not threaded at its ends; it is joined with listed compression or set-screw fittings matched to the location.

Its biggest advantage is the balance between protection and labor. EMT is rigid enough to protect conductors from normal physical exposure yet light enough to cut and bend efficiently. For long exposed runs with multiple offsets, that combination can reduce both material weight and installation time.

EMT is not the universal answer for severe physical damage or aggressive corrosion. The fittings, environmental exposure, and local code requirements matter as much as the tubing itself. Where a metallic raceway is relied on as part of the equipment grounding path, continuity through couplings, connectors, boxes, and fittings must be maintained.

2. RMC: Rigid Metal Conduit

Rigid metal conduit (RMC) is a thick-wall, threaded metal raceway used where a project needs substantial mechanical protection. Steel is common, while other listed metallic constructions are available for specific environments. Threaded couplings and fittings create a very robust raceway system.

RMC is heavier and more labor-intensive than EMT, but that extra material provides a major advantage where conduit is exposed to damage, used as part of service equipment, installed outdoors, or specified for demanding industrial conditions. The tradeoff is cost, handling weight, and the tools required for cutting and threading.

3. IMC: Intermediate Metal Conduit

Intermediate metal conduit (IMC) sits between EMT and RMC in the common metal-raceway spectrum. It is a threaded steel raceway with a thinner wall and lower weight than RMC while still providing strong mechanical protection.

IMC is useful when a design calls for a threaded raceway but the weight of RMC is unnecessary. It is often considered for industrial, service, outdoor, and exposed applications where its listing and the installation environment permit it. Because RMC and IMC can look similar once installed, the product markings should be checked rather than judging by appearance alone.

4. PVC Conduit and Other Rigid Nonmetallic Raceway

Rigid PVC conduit is a nonmetallic raceway valued for corrosion resistance, low weight, and suitability for many wet, underground, and concrete-encased installations. Common electrical PVC systems include Schedule 40 and Schedule 80 products, with the required choice depending on the level of physical protection and the conditions of use.

PVC does not provide a metallic grounding path. A properly sized equipment grounding conductor is therefore normally run with the circuit conductors. Temperature also matters: long exposed PVC runs expand and contract more than metal, so layout and expansion provisions can become important.

Underground does not mean “dry.” Raceways installed below grade can contain moisture, so the conductors and fittings used with the conduit must also be suitable for the actual location.

5. FMC: Flexible Metal Conduit

Flexible metal conduit (FMC) is formed from a helically wound metal strip that allows the raceway to bend around equipment and through short, complex paths without field-bending rigid tubing. It is especially useful where vibration, movement, or difficult geometry makes a rigid final connection impractical.

FMC should not be treated as a general replacement for long rigid conduit runs. Its permitted uses, support requirements, grounding role, and environmental limitations depend on the installation. It is commonly used as a short connection to equipment rather than as the primary raceway across an entire room.

6. LFMC: Liquidtight Flexible Metal Conduit

Liquidtight flexible metal conduit (LFMC) adds a liquidtight outer jacket around a flexible metal core. The construction makes it useful where equipment needs a flexible connection and the raceway may be exposed to moisture, oil, or outdoor conditions within the product’s listing.

Common examples include HVAC equipment, pumps, motors, and machinery. The connector is part of the liquidtight system, so a jacketed raceway paired with the wrong fitting does not create a complete wet-location installation.

7. ENT: Electrical Nonmetallic Tubing

Electrical nonmetallic tubing (ENT) is a lightweight, corrugated raceway that bends by hand. That flexibility can speed concealed installations through framing and certain concrete construction where ENT is permitted.

ENT is not intended to provide the same physical protection as RMC or IMC. Selection depends on whether the raceway will remain concealed, the type of building construction, environmental conditions, and the restrictions that apply to the listed product.

8. LFNC: Liquidtight Flexible Nonmetallic Conduit

Liquidtight flexible nonmetallic conduit (LFNC) provides a flexible raceway without a metallic core. It can be useful around equipment where corrosion resistance, moisture resistance, and flexibility matter more than the mechanical strength of metal.

Because the raceway is nonmetallic, the equipment grounding path must be provided separately where required. As with LFMC, use fittings listed for the exact raceway type and application.

Metallic vs. Nonmetallic Conduit

The choice between metal and nonmetallic conduit is not simply a preference for steel versus plastic. Metal raceways generally offer greater mechanical protection and, for certain listed raceways installed correctly, can participate in the equipment grounding path. Nonmetallic raceways resist corrosion and avoid electrical continuity concerns through the raceway itself, but they normally require a separate equipment grounding conductor.

The best material can also change within one project. An underground PVC run may transition to a metal raceway where the conduit emerges into a more exposed area, provided the transition fittings and bonding method are suitable for both wiring methods.

How to Choose the Right Conduit Type

A practical selection process starts with the conditions the raceway will actually see.

1. Identify the location. Determine whether the raceway is indoors, outdoors, underground, wet, damp, corrosive, exposed, or concealed.
2. Evaluate physical damage. A protected wall cavity and an exposed industrial aisle do not demand the same level of mechanical protection.
3. Decide whether flexibility is required. Motors, compressors, HVAC equipment, and vibrating machinery often need a flexible final connection.
4. Plan the grounding path. Confirm whether the chosen metallic raceway is permitted to serve as an equipment grounding conductor in the specific installation or whether a separate conductor is required.
5. Check conductor and fill requirements. Select the raceway size from the conductor count, conductor dimensions, and applicable fill rules rather than from appearance.
6. Match every fitting to the raceway and environment. Couplings, connectors, expansion fittings, hubs, and boxes need ratings suitable for the same conditions as the conduit.
7. Consider installation and maintenance. Bending difficulty, pulling distance, future conductor additions, corrosion exposure, and access can change the best material even when several types are code-permitted.

Conduit Standards Matter Because the Types Are Not Interchangeable

UL maintains separate product standards for common raceway families, including UL 797 for EMT, UL 651 for PVC conduit, UL 360 for liquidtight flexible metal conduit, UL 1 for flexible metal conduit, and UL 1653 for electrical nonmetallic tubing. That separation reflects an important field reality: each raceway type is evaluated for a different construction and set of intended uses, so “conduit” on a material list is not enough information to specify a compliant system.

Common Conduit Selection Mistakes

• Choosing by price alone without checking wet-location, corrosion, or physical-damage requirements.
• Assuming any flexible conduit is liquidtight. FMC and LFMC are different raceway types.
• Using nonmetallic conduit without planning the equipment grounding conductor.
• Treating Schedule 40 and Schedule 80 PVC as interchangeable where physical protection requirements differ.
• Selecting conduit size before calculating conductor fill and pull conditions.
• Mixing raceway and fitting types without verifying that the fittings are listed for the transition and location.
• Ignoring expansion and contraction on long exposed nonmetallic runs.
• Assuming a metallic raceway automatically provides an effective grounding path even when couplings or connectors are loose, damaged, or incorrectly installed.

The Bottom Line

EMT is a strong all-around choice for many commercial interior runs, RMC and IMC provide heavier mechanical protection, PVC excels where corrosion and underground exposure matter, and flexible raceways solve movement and difficult-equipment connections. The right conduit is the one whose listing, fittings, grounding method, conductor fill, and environmental rating all match the actual installation.

After choosing the raceway type, verify conductor size and circuit requirements with Lumera’s wire gauge and ampacity guide and use the conduit-fill calculation for the final raceway size.