Electrical Conduit Types Compared: EMT, PVC, Rigid, and Flexible

Electrical conduit protects conductors from physical damage, moisture, and chemical exposure while providing a system that can be rewired without opening walls. Choosing the right conduit type involves matching the material to the application — outdoor, indoor, burial, or flexible — along with understanding cost, installation complexity, and NEC requirements.

Why Use Conduit?

In many installations, NM-B cable (Romex) is the simplest and most economical wiring method. But conduit is required or preferred in several scenarios:

Exposed wiring in garages, basements, and commercial spaces where cable would be subject to physical damage
Outdoor and underground runs where direct burial cable isn’t appropriate or where future rewiring access is needed
Wet locations where conduit with appropriate fittings provides better moisture protection
Commercial construction where EMT is the standard wiring method
Future proofing — conduit allows wire replacement without opening walls

EMT (Electrical Metallic Tubing)

What It Is

EMT is thin-wall steel conduit — the most common conduit type in commercial and industrial construction, and increasingly used in residential garages and exposed basement runs. It’s characterized by its light weight (compared to rigid steel), blue-gray finish, and compression or set-screw fittings.

Properties

Material: Cold-drawn steel (zinc-coated inside and out)
Wall thickness: Approximately 0.042”–0.065” depending on trade size — much thinner than rigid
Available sizes: 1/2”, 3/4”, 1”, 1-1/4”, 1-1/2”, 2”, 2-1/2”, 3”, 3-1/2”, 4”
Length: 10-foot sticks standard
Connection method: Set-screw or compression couplings and connectors
Color: Bright zinc inside, zinc or galvanized outside

NEC Applications

Per NEC Article 358, EMT can be used:

In both exposed and concealed locations
In dry, damp, or wet locations with appropriate fittings (watertight fittings for wet/damp)
In concrete (when used with appropriate listed fittings)
Not for direct burial without special corrosion protection
Not where subject to severe physical damage

Bending EMT

EMT is field-bendable using a conduit bender — a tool that creates precise bends without kinking the conduit. Common bends:

90-degree bend (stub-up or corner)
Offset (moves conduit around an obstacle)
Saddle (three-point offset over a pipe or obstacle)

EMT benders: Available in each trade size. A 1/2” and 3/4” bender handle the most common residential/light commercial sizes. Klein Tools, Ideal Industries, and Greenlee are the dominant brands.

Advantages and Disadvantages

Advantages:

Lightweight and easy to work with
Bends easily in the field
Provides a good equipment ground path through the metal conduit itself
Rewirable — pull new wire without opening walls
Accepted in nearly all applications (with appropriate fittings)

Disadvantages:

More labor-intensive than cable methods
Requires bending skills
Metal fittings can be harder to tighten in tight spaces
Not for direct burial without corrosion protection

PVC Conduit (Schedule 40 and Schedule 80)

What It Is

PVC (polyvinyl chloride) conduit is plastic conduit — lighter than metal, corrosion-resistant, and commonly used for underground and outdoor runs.

Schedule 40 vs Schedule 80

Schedule 40 PVC: Standard wall thickness, appropriate for most conduit-in-slab and burial applications. Gray color (electrical) or white (plumbing — not for electrical use).
Schedule 80 PVC: Thicker wall, greater crush strength. Used in applications where physical damage is a greater concern (exposed surfaces in some commercial applications, above-grade outdoor where more protection is needed).

Important: Electrical PVC conduit is gray. White PVC is plumbing pipe and is NOT listed for electrical use.

Properties

Material: PVC (polyvinyl chloride)
Fittings: Solvent-welded PVC fittings (no-hub PVC cement required for permanent connections)
Available sizes: Same as EMT, 1/2” through 4”+
Temperature limitations: PVC becomes brittle below -20°F and expands significantly with temperature changes — expansion fittings required for long runs

NEC Applications

Per NEC Article 352, PVC conduit can be used:

Exposed (Schedule 80 required where subject to physical damage)
Concealed
Direct burial — the most common reason to choose PVC
In wet and corrosive locations
Underground under buildings (concrete-encased)

Not for use:

Where exposed to temperatures exceeding the conduit’s listing
Where subject to severe physical damage without Schedule 80
In certain hazardous locations (consult NEC Article 352)

Burial Depth Requirements (NEC Table 300.5)

PVC conduit minimum cover depths:

Location	PVC Conduit Depth
General	18 inches
Under a building	0 inches (direct contact permitted)
Under streets, roads, and driveways	24 inches
Under residential driveways (one/two-family only)	18 inches
In or under 4” concrete slab	4 inches

Advantages and Disadvantages

Advantages:

Corrosion-resistant — ideal for direct burial and coastal environments
No grounding path through conduit (separate ground wire required — considered both advantage and disadvantage)
Easy to work with — no bending tool for gentle bends (PVC can be heated with a heat gun for bends)
Lower material cost than metal conduit

Disadvantages:

PVC does not serve as a ground path — separate EGC required
Expands and contracts with temperature (requires expansion fittings in long runs)
Brittle when cold (care needed in freezing temperatures)
Schedule 40 not suitable for applications with physical damage risk

Rigid Metal Conduit (RMC)

What It Is

RMC (Rigid Metal Conduit) is heavy-wall steel conduit — the industrial standard for maximum protection. Also called rigid steel or rigid galvanized conduit (RGC). Threaded at both ends, uses threaded fittings and couplings.

Properties

Material: Galvanized steel (most common) or stainless steel or aluminum for corrosive environments
Wall thickness: Approximately 0.141” for 1/2” trade size — significantly thicker than EMT
Fittings: Threaded — requires threaded couplings, locknuts, and connectors
Length: 10-foot sticks with factory threads
Weight: Significantly heavier than EMT

NEC Applications

RMC may be used in all locations — above ground, below ground, in concrete, in hazardous locations, in corrosive environments (with appropriate material selection). It’s permitted everywhere any other conduit is permitted, and it’s the required method in some high-protection situations.

Most common uses:

Service entrance conduit from meter to main panel
Outdoor service masts
Industrial locations with severe physical damage risk
Hazardous (classified) locations

Advantages and Disadvantages

Advantages:

Maximum physical protection
Can be direct-buried (minimum 6” cover with RMC)
Threaded fittings provide excellent watertight connections
Serves as ground path
Longest burial depth reduction — only 6 inches needed

Disadvantages:

Heavy — installation is labor-intensive
Requires pipe vise and threader for field cuts
Most expensive metal conduit option
Overkill for most residential applications

Intermediate Metal Conduit (IMC)

IMC is a middle ground between EMT and RMC — heavier than EMT but lighter than RMC. It accepts the same fittings as RMC (threaded) and is permitted in the same locations. Less common than either EMT or RMC but useful when additional strength over EMT is needed without the full weight of RMC.

Flexible Metal Conduit (FMC) and Liquidtight FMC

FMC (Flexible Metal Conduit)

FMC is corrugated, flexible metal conduit — spirally wound interlocking steel that provides flexibility for equipment connections, motor connections, and areas where rigid conduit is difficult to run.

Common uses:

Final connection to motors and equipment that vibrate (AC units, compressors)
Luminaire connections in dropped ceilings
Short transition between rigid conduit and fixed equipment

Limitations: Not suitable for wet locations, direct burial, or underground without liquidtight jacket.

LFMC (Liquidtight Flexible Metal Conduit)

LFMC is FMC with a PVC jacket — provides the flexibility of FMC with watertight protection suitable for outdoor equipment connections.

Common uses:

Air conditioning and refrigeration equipment connections outdoors
Outdoor equipment with vibration (generators, pumps)
Indoor wet locations

Maximum length: NEC limits FMC and LFMC use to 6 feet for certain applications (equipment connections). Longer runs must use rigid conduit methods.

Conduit Selection Quick Reference

Application	Recommended Conduit
Garage interior exposed runs	EMT
Underground between house and detached garage	PVC Schedule 40 or HDPE
Service entrance mast	RMC
Outdoor equipment connection (AC unit)	LFMC
Interior commercial	EMT
Direct burial in soil	PVC Schedule 40
Concrete-encased underground	PVC Schedule 40 or 80
Corrosive chemical environment	PVC Schedule 80 or FRE
Panel interior connections	EMT or rigid

Conduit Fittings and Accessories

Connectors

Attach conduit to boxes:

Set-screw connectors (EMT): Tighten with a hex wrench; suitable for dry locations
Compression connectors (EMT): More watertight; required for wet/damp locations
Threaded couplings (RMC): Thread onto conduit; use with locknuts and bushings

Couplings

Connect two sections of conduit:

EMT couplings: Set-screw or compression types
PVC couplings: Solvent-welded

Pulling Elbows

90° pull fittings with a removable cover for pulling wire around corners. Required when the total number of bends in a conduit run exceeds NEC limits (360° total in any run between boxes).

Straps and Supports

Conduit must be supported within 3 feet of each box and every 10 feet for EMT (check NEC Table 358.30(A) for specifics). Straps and hangers should be listed for the conduit type.

Choosing the Right Fittings for Wet Locations

Any conduit installed in a wet or damp location requires fittings rated for that location:

EMT: Use compression fittings (set-screw is for dry only)
PVC: Solvent-welded fittings are inherently watertight
LFMC: Use liquidtight fittings

Using dry-location fittings in wet environments allows water into the conduit — defeating the purpose and creating corrosion at connections.

Selecting the right conduit type simplifies installation, ensures code compliance, and provides the right level of physical protection for the application. For residential homeowners and light commercial work, EMT for exposed interior runs and PVC for underground is the most common and cost-effective combination.