Conduit wiring is an electrical installation method where wires run inside protective tubing rather than being bundled into a pre-made cable. The conduit itself is a hollow pipe, made of metal or plastic, that creates a dedicated pathway (called a raceway) through walls, ceilings, floors, or underground. Wires are pulled through the conduit after it’s installed, which makes the system highly flexible since you can add, remove, or replace wires without tearing into walls.
How Conduit Differs From Standard Cable
Most homes in the United States are wired with non-metallic cable, commonly known by the brand name Romex. This cable bundles multiple wires together inside a plastic sheathing, and it gets stapled directly to wall studs and joists behind drywall. It’s fast to install and inexpensive, which is why it dominates residential construction.
Conduit takes a different approach. Instead of a pre-packaged cable, you first mount the empty tubing along your desired route, then pull individual wires through it. This adds significant labor and cost, but the tradeoff is real physical protection for the wires. In a garage, basement, or workshop where something might get leaned against the wall or banged into it, conduit prevents damage that would expose live wiring. It’s also the standard in commercial and industrial buildings, where building codes are stricter and wiring runs face more wear and tear. Some cities, notably New York, require metal-clad wiring throughout residential buildings as well, largely to protect against rodent damage.
The other major advantage is future-proofing. If you ever need to run additional circuits or upgrade your wiring, you can pull new wires through existing conduit without opening up walls. With standard cable, that kind of change usually means cutting drywall and starting from scratch.
Types of Conduit
Conduit comes in several materials, each suited to different environments and budgets. The main categories are metal and PVC (plastic), and within those, there are important distinctions.
Rigid Metal Conduit (RMC)
This is the heavy-duty option. RMC has thick, threaded walls, typically made of steel (often galvanized with a zinc coating to resist corrosion). Its thickness makes it extremely durable against physical impact, and the steel walls also shield wires from electromagnetic interference, which matters around sensitive equipment. RMC is the go-to choice for industrial settings, hazardous locations, and anywhere the conduit will take a beating. The downside is weight, cost, and the effort required to cut and thread it.
Intermediate Metal Conduit (IMC)
IMC is essentially a lighter version of RMC. It’s also threaded and offers strong impact protection, but with thinner walls that make it easier to work with. It handles heavy-duty applications well while saving some weight and material cost compared to rigid metal conduit.
Electrical Metallic Tubing (EMT)
EMT is the most common metal conduit in everyday commercial and residential use. It’s thin-walled, unthreaded, and made of coated steel or aluminum. Because it’s lighter and easier to bend and cut, EMT installs significantly faster than rigid conduit. The tradeoff is that it’s not as tough. EMT works well indoors but is generally not recommended for outdoor or underground use, since it’s more vulnerable to damage and requires special watertight fittings for wet locations.
PVC Conduit
PVC conduit is the plastic alternative: lightweight, corrosion-proof, and inexpensive. It resists moisture, sunlight, and chemical exposure, making it especially popular for outdoor projects and underground burial. PVC won’t conduct electricity, which adds a layer of safety, and it’s simple to cut and glue together. The limitation is that PVC can’t be bent on-site the way metal tubing can. Instead, you use pre-formed fittings and elbows to change direction. It also offers no electromagnetic shielding and less impact resistance than metal.
Fiberglass Conduit
For underground installations, fiberglass conduit is a preferred choice in utility, commercial, and industrial applications. It’s approved for both direct burial and concrete-encased burial, and it handles corrosive soil conditions better than metal. The National Electrical Code covers fiberglass conduit in trade sizes ranging from half an inch to six inches in diameter.
PVC-Coated Steel Conduit
When you need both mechanical strength and corrosion resistance, PVC-coated steel splits the difference. The steel core handles impact and provides grounding capability, while the PVC coating protects against harsh chemical or moisture exposure.
How Conduit Acts as a Ground Path
One feature that surprises people new to conduit wiring: steel conduit doesn’t just protect wires, it can also serve as the grounding path for the circuit. The National Electrical Code recognizes steel and stainless steel RMC, IMC, and EMT as valid equipment grounding conductors. This means that if a hot wire inside the conduit contacts the metal tubing, the fault current has a low-resistance path back to the panel, which trips the breaker.
For this to work, every joint in the conduit run must be mechanically tight and electrically continuous. Threads need to be clean and undamaged, and fittings must seat firmly against enclosures. For circuits operating at higher voltages (over 250 volts to ground), additional bonding hardware like bonding-type locknuts or bushings is required at certain connection points. Any expansion fittings or telescoping sections also need bonding jumpers to maintain that continuous ground path.
Installing Conduit: Bending and Mounting
Metal conduit, particularly EMT, gets shaped on-site using a conduit bender. This is a hand tool with a curved head: you insert the tubing into the head and step on a foot pedal to form the bend to whatever angle the run requires. Markings on the bender help you align the pipe for precise, repeatable results.
The standard bends every electrician learns are the 90-degree bend (to turn a corner), the offset (to step the conduit out from a wall or around an obstacle), the back-to-back 90 (two right-angle bends creating a U-shape), and the saddle bend (which humps over a pipe or obstruction and comes back to the original plane). Getting these bends accurate matters because wire has to slide smoothly through the finished run. Kinked or poorly aligned conduit makes pulling wire difficult or impossible.
PVC conduit doesn’t get bent with a tool. Instead, you cut straight sections to length and connect them with pre-molded fittings, elbows, and junction boxes using PVC cement.
Pulling Wire Through Conduit
Once the conduit is mounted and all the joints are made, the wiring goes in. This is a separate step called a wire pull, and it has its own set of tools and techniques.
The basic tool is a fish tape: a long, flexible strip of steel or fiberglass that you push through the conduit from one end. Once it reaches the other side, you attach the wires to it and pull them back through. Fish tapes come in various lengths (commonly 25 to 240 feet) depending on how far the run extends. For shorter or simpler runs, a pull string or poly pull line works as well.
Friction is the enemy during a wire pull. The longer the run and the more bends it contains, the harder it is to drag wire through. That’s where wire-pulling lubricant comes in. These come as gels, waxes, or foams that coat the wire to reduce friction against the conduit walls. A common pro technique is to tie a rag to the end of a pull line, coat it with lubricant, and pull it through the conduit before the wire goes in. This both clears debris and pre-lubricates the entire pathway.
The National Electrical Code limits the total number of degrees of bends in a single conduit run (generally no more than 360 degrees, or the equivalent of four 90-degree turns, between pull points). Beyond that, the friction becomes too great to pull wire safely without damaging the insulation. If a route requires more turns, you add a junction box at an intermediate point to break the pull into segments.
Where Conduit Wiring Is Required or Preferred
Local building codes dictate when conduit is mandatory versus optional. In general, conduit is required or strongly preferred in these situations:
- Exposed wiring: Any wire running along the surface of a wall, ceiling, or structure rather than inside a framed cavity typically needs conduit protection.
- Garages and basements: Areas where wiring is within reach and vulnerable to physical damage.
- Commercial and industrial buildings: Conduit is standard practice for nearly all branch circuits in these settings.
- Underground runs: PVC or fiberglass conduit protects buried wiring from moisture, soil pressure, and accidental dig-ins.
- Corrosive or hazardous environments: Chemical plants, food processing facilities, and similar settings use conduit rated for the specific exposure.
- Outdoor installations: Where wiring faces weather, UV exposure, and temperature swings.
In standard residential construction behind drywall, conduit is code-compliant but rarely used because the labor and material cost is substantially higher than running cable. A wire is considered protected when it passes through framing with at least an inch and a half of wood between the wire and the outer edge, then gets covered by half-inch drywall. That combination prevents a standard drywall screw from reaching the wire. Where that protection exists, cable is the norm. Where it doesn’t, conduit fills the gap.