8.1 Raceway Types & Selection (Articles 342-366)

Why Raceway Selection Matters on the Exam

A raceway is an enclosed channel designed expressly for holding conductors. The NEC defines nine common raceway types across Articles 342 through 366, and the Virginia Journeyman exam expects you to know which type belongs in which environment, what Article governs it, and how it must be supported. Choosing the wrong raceway for a wet location or an area exposed to physical damage is a common exam trap — the answer options will all "work" electrically, but only one complies with the Code for the stated condition.

Metal Raceways

Rigid Metal Conduit (RMC) — Article 344: Threaded, thick-wall steel or aluminum conduit. RMC is the most mechanically rugged raceway and is permitted in almost any location: underground, in concrete slabs, exposed to physical damage, wet, corrosive (with proper coating), and hazardous locations. RMC is the default answer when a question describes severe physical abuse or direct burial without additional protection.

Intermediate Metal Conduit (IMC) — Article 342: Threaded like RMC but with a thinner wall — about halfway between RMC and EMT. IMC is lighter and less expensive than RMC while still permitted in most of the same locations, including underground and in concrete. IMC cannot be used where it will be subject to severe physical damage unless it qualifies under the exceptions in 342.10.

Electrical Metallic Tubing (EMT) — Article 358: Thin-wall, unthreaded metallic tubing joined by setscrew or compression fittings. EMT is the workhorse of commercial and residential indoor wiring. It is not permitted "where subject to severe physical damage" per 358.12(1), though it can be used under floors where adequately protected. EMT is the most common raceway answer for indoor, non-hazardous, non-abuse installations.

Flexible Metal Conduit (FMC) — Article 348: A helically wound, flexible metal raceway used to connect equipment that vibrates or moves, such as motors and transformers. FMC is not a substitute for fixed raceway in most permanent runs. Its flexibility comes with restrictions: FMC has a tighter support spacing (4.5 ft maximum per 348.30) and a 1-ft secure-within requirement at terminations.

Liquidtight Flexible Metal Conduit (LFMC) — Article 350: Like FMC but with a liquidtight plastic jacket, making it suitable for wet locations and outdoor equipment connections. Common for air conditioner disconnects and pump connections.

Nonmetallic Raceways

Rigid PVC Conduit (Schedule 40 and 80) — Article 352: A nonmetallic, corrosion-proof raceway widely used underground and in wet or corrosive environments. Schedule 40 is the standard wall; Schedule 80 has thicker walls and is required where the conduit is "subject to physical damage" per 352.10(F). PVC expands and contracts significantly with temperature, so expansion fittings per 352.44 are required when the expected length change reaches ¼ inch or more. Support spacing varies by trade size — consult Table 352.30, not a fixed 10 ft.

Reinforced Thermosetting Resin Conduit (RTRC) — Article 355: Fiberglass conduit, electrically nonconductive and corrosion-resistant. Similar in application to PVC but can be used in some physical-damage locations where PVC Schedule 40 cannot.

Liquidtight Flexible Nonmetallic Conduit (LFNC) — Article 356: A flexible, liquidtight, nonmetallic raceway for wet, damp, or corrosive environments where flexibility is needed. Common in chemical plants and outdoor equipment.

Electrical Nonmetallic Tubing (ENT) — Article 362: A pliable, corrugated raceway used only in concealed locations — behind walls, in floors, or above ceilings. ENT is not permitted in exposed locations subject to physical damage per 362.12(1) and cannot be used outdoors.

Selection by Environment

Trade Sizes

Raceway trade sizes use the same nominal system across types: 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 3-1/2, 4, 5, and 6 inches. Metric designators (16, 21, 27, 35, 41, 53, 63, 78, 91, 103, 129, 155) appear alongside trade sizes in the NEC. A trade size 3/4 EMT and a trade size 3/4 RMC have the same nominal trade size but different internal diameters — which matters for conduit fill calculations.

Supports and Spacing

Support rules are exam favorites because they are article-specific and easy to test:

The 3-ft termination rule has an exception: if structural framing prevents securing within 3 ft, you may secure within 5 ft for RMC, IMC, and EMT. FMC has no such exception — its 1-ft rule is strict. Horizontal runs through bored or punched framing members count as supported at those points, but the raceway must still be secured within the required distance of terminations.

Number of Conductors in One Raceway — Overview

How many conductors fit in a given raceway is governed by Chapter 9, Table 1 fill limits, detailed in the next section. The key concept: every conductor — including the equipment grounding conductor — occupies physical space, and the total cross-sectional area of all conductors cannot exceed the permitted fill percentage of the raceway's internal area.

Exam Traps

• PVC Schedule 40 vs 80: A question will describe "subject to physical damage" — Schedule 40 alone does not qualify; you need Schedule 80.
• EMT in physical-damage areas: EMT is NOT permitted where subject to severe physical damage. If the scenario describes a warehouse floor or loading dock, EMT is wrong.
• ENT outdoors or exposed: ENT is concealed-only and never permitted in exposed or outdoor locations.
• FMC support spacing: FMC's 4.5-ft maximum is the tightest of all metal raceways. Do not confuse it with EMT's 10 ft.
• Article number confusion: RMC is Article 344, not 342. Article 342 is IMC. The exam may list both as distractors.