Quick answer
Electrical conduit is a tube or pipe, made of metal or plastic, that holds and protects individual wires as they run between boxes, panels and equipment.
The National Electrical Code calls it a raceway. Each type has its own NEC article, listing standard and allowed locations, and some metal types also serve as the ground path.
Quick facts
The key facts about Electrical Conduit, with sources:
- Also called
- Raceway (NEC term)
- Common metal types
- EMT, rigid metal conduit (RMC), IMC, flexible metal conduit
- Common plastic types
- Rigid PVC (Schedule 40 and 80), ENT
- Steel EMT standard
- UL 797, Edition 9 4
- Rigid steel standard
- UL 6, Edition 15 5
- PVC conduit standard
- UL 651, Edition 8 6
- Metal raceways must be
- Bonded for electrical continuity 7
Key takeaways
- Conduit is a protective tube; the wires inside are separate insulated conductors such as THHN.
- Metal types (EMT, rigid, IMC) resist damage; PVC resists corrosion and is common underground.
- Each type has its own UL standard and NEC article that says where it may go 4 6.
- Metal conduit must stay electrically continuous, because it can carry fault current 7.
- Most houses use cable, not conduit; conduit shows up in basements, garages, outdoors and in some cities by rule.
What conduit is
Conduit is armor for wires. Instead of a jacketed cable like NM-B (Romex), an installer runs an empty tube first, then pulls single insulated wires through it.
The tube shields the wires from nails, tools, sunlight, water and crushing. It also makes later changes easier: wires can be pulled out and new ones pulled in without opening walls.
The NEC groups conduit with other enclosed channels under the word raceway. Rigid steel, EMT and PVC are each covered by their own UL standard, which sets the wall thickness, coatings and fittings 5 4 6.
How a conduit system works
A conduit run is a chain: tube, fittings, bends and boxes. Couplings join lengths. Connectors lock the tube to a junction box or panel. Bends are made with a bender or bought as factory elbows.
Wires are pulled in after the tube is in place. The NEC limits how full the tube can be, so wires stay cool and can be pulled without damage. The usual limits in NEC Chapter 9 are 53% of the area for one wire, 31% for two, and 40% for three or more 1.
With metal conduit, the tube itself can act as the equipment grounding conductor when the type allows it. That only works if every joint is tight. OSHA requires metal raceways to be bonded for continuity and coatings removed at contact points 7.
- Panel or boxconnector locks the tube in place
- Conduit lengthsjoined by couplings
- Bendsfield-bent or factory elbows
- Pull pointbox or conduit body every few bends
- Wires pulled inindividual insulated conductors
- Device or equipmentoutlet, light, disconnect or unit
Source: [7]
Types of electrical conduit
| Type | Material | Strength | Typical home use |
|---|---|---|---|
| EMT (electrical metallic tubing) | Thin-wall steel, zinc coated 4 | Medium | Exposed runs in garages, basements, shops |
| RMC (rigid metal conduit) | Thick-wall steel, threaded 5 | Highest | Service masts, exposed outdoor runs |
| IMC (intermediate metal conduit) | Steel, thinner than RMC | High | Similar to RMC, lighter to handle |
| Rigid PVC, Schedule 40 | Plastic 6 | Medium | Underground and wet locations |
| Rigid PVC, Schedule 80 | Thicker-wall plastic 6 | Higher | Where exposed to physical damage |
| FMC (flexible metal conduit) | Spiral steel or aluminum | Low | Short runs to motors and fixtures |
| LFMC (liquidtight flex) | Flex with plastic jacket | Low | AC condensers, pool pumps, damp spots |
| ENT (electrical nonmetallic tubing) | Corrugated plastic | Low | Concealed in walls and slabs where allowed |
Example: what a conduit run to a detached garage involves
An illustrative example of the parts list and rules an electrician weighs for an underground run. No prices; see the cost section.
| Choice | Typical option | Why |
|---|---|---|
| Conduit underground | Schedule 40 PVC 6 | Does not rust in soil |
| Where it rises above ground | Schedule 80 PVC or rigid metal 6 5 | Resists damage from mowers and bumps |
| Wires inside | Wet-rated single conductors, e.g. THWN-2 | Underground conduit is a wet location |
| Ground path | Separate green or bare grounding wire | PVC cannot carry fault current |
| Fill check | 40% of conduit area for 3+ wires 1 | Keeps wires cool and pullable |
| Voltage drop check | Upsize wire on long runs | See voltage drop |
Example only. Burial depth, wire type and fittings depend on your adopted NEC edition and local rules.
Where you find conduit in and around a home
- The service mast on the roof or wall, carrying the utility wires to the meter.
- Exposed wiring on unfinished basement or garage walls, where cable could be damaged.
- Underground feeders to garages, sheds, pools and subpanels.
- Short flex whips to AC condensers, water heaters and pool pumps.
- Outdoor runs to EV chargers, generators and disconnects.
- Whole homes in a few cities whose local codes favor or require raceways.
Strengths and weak spots of conduit
What it does well
- Strong physical protection for exposed wires.
- Wires can be added or replaced later by pulling new ones.
- Metal types can serve as the ground path when listed and tight 7.
- PVC handles wet and corrosive spots that would rust steel.
Where it falls short
- More labor than cable: bending, fittings, then pulling.
- Fill limits cap how many wires fit 1.
- Steel can rust where coatings are damaged; PVC expands and contracts with heat.
- Loose metal fittings can break the ground path without anyone noticing.
What conduit cannot do
Conduit protects wire; it does not make undersized wire safe. The wire inside still has to match the breaker and the load.
Plastic conduit does not conduct, so it never counts as a ground path. A separate grounding wire must run with the circuit.
Conduit also does not make wires waterproof. Water gets into underground and outdoor conduit as a matter of course, so the wires inside must carry a wet rating.
What drives the cost of conduit work
Conduit jobs cost more than cable jobs mostly because of labor. The drivers are the conduit type and size, the run length, the number of bends and boxes, trenching depth for underground runs, and wire size and count.
Lifespan depends on the setting. Galvanized steel resists rust until its coating is broken; PVC does not rust, but it can crack where it is hit, which is why heavier Schedule 80 is used where damage is likely 6.
Manufacturers list trade sizes from ½ inch up to 4 inches for steel EMT 8.
We publish no dollar figures without dated quotes. See what drives electrical costs or try the electrical project cost tool.
How conduit gets installed
A permitted conduit job moves through six stages, and two of them are inspections. The list is for following a quote, not a how-to.
- Electrician plans the route, type and size, including fill and voltage drop.
- Permit is pulled where the town requires one.
- Conduit, boxes and supports are installed; trenches are dug for underground runs.
- Rough-in inspection checks the raceway before walls or trenches close.
- Wires are pulled, terminated and tested.
- Final inspection, then power on.
Safety and risk
Never open conduit fittings, boxes or panels to look inside. Wires in conduit can be live even when a light is off. Damaged, crushed or rusted-through conduit near live equipment is a job for a licensed electrician.
See how electrical permits work in most towns.
What an owner can watch for
- Rust, cracks or crushed sections on exposed outdoor conduit.
- Fittings pulled apart at a box, leaving wire exposed.
- PVC that has bowed or separated in the sun, a sign of missing expansion fittings.
- Missing covers on boxes or conduit bodies. OSHA requires covers on boxes and fittings 7.
Warning signs and when to call a pro
- Exposed wire where conduit has separated from a box.
- Water pouring from a conduit into a panel or meter.
- Sparks, buzzing or a hot smell near any conduit or box.
- A mild tingle from metal conduit or equipment: stop touching it and call an emergency electrician.
Rules and standards that apply
| Authority | Rule or standard | What it covers |
|---|---|---|
| NFPA | NFPA 70 (NEC) 2023; 2026 edition published 2 | Conduit articles, fill tables, grounding |
| UL Standards & Engagement | UL 797, Ed. 9, rev. 28 Apr 2023 4 | Steel EMT |
| UL Standards & Engagement | UL 6, Ed. 15, 28 Nov 2022 5 | Rigid steel conduit |
| UL Standards & Engagement | UL 651, Ed. 8, rev. 8 Apr 2026 6 | Schedule 40/80 PVC conduit |
| OSHA (workplaces) | 29 CFR 1910.305(a)(1)(i) 7 | Metal raceways bonded for continuity |
Adoption of each NEC edition varies by state and town.
Conduit vs cable
| Feature | Conduit + single wires | Cable (NM-B, MC) |
|---|---|---|
| Protection | High (metal) to medium (PVC) | Low (NM-B) to medium (MC) |
| Rewiring later | Pull new wires | Replace whole cable |
| Wet locations | Allowed with wet-rated wire | NM-B not allowed |
| Labor | Higher | Lower |
| Ground path | Metal types can be the ground | Ground wire in the cable |
Wire size inside either method follows the same wire gauge rules.
Common misconceptions
- Myth Romex can go inside conduit for protection anywhere.
- Reality NM-B is not allowed in wet locations, and underground conduit counts as wet.
- Myth Conduit keeps wires dry.
- Reality Underground and outdoor conduit fills with condensation; wires need a wet rating.
- Myth PVC conduit grounds the circuit.
- Reality Plastic does not conduct; a separate ground wire is required.
- Myth More wires always fit if they pull.
- Reality NEC fill limits cap the share of the tube wires may fill 1.
How location changes conduit rules
Which NEC edition applies, and any local amendments, depends on your state and city. A few large cities have long favored raceways over cable in some buildings. Frost depth and soil also change how deep underground conduit goes. NFPA tracks edition adoption by state 3.
When conduit matters to you
You will meet conduit when wiring goes outdoors, underground or onto bare walls. If a quote says conduit, ask which type and why. If it says cable in a garage or basement, ask whether it is protected where it can be hit.
For bigger jobs such as a shop feeder or a charger installation, the conduit type and size drive much of the labor. Ask for both on the quote.
- If Buried in soil
- Then PVC, with a heavier section where it rises
- If Exposed indoors where it could be hit
- Then EMT
- If Outdoor mast or high-impact spot
- Then Rigid metal or IMC
- If Short run to a vibrating motor
- Then Flexible or liquidtight flex
Questions about Electrical Conduit
What is electrical conduit used for?
Conduit protects wires from damage, moisture and sunlight. It is used where cable would be exposed: garage and basement walls, outdoors, underground and on service masts.
It also lets electricians pull new wires later without opening walls. Metal conduit can serve as the ground path when the type is listed for it and every fitting is tight.
What are the main types of conduit?
The main types are EMT, rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid PVC in Schedule 40 and 80, flexible metal conduit, liquidtight flex and ENT. Metal types give the most protection. PVC resists corrosion and is common underground. Flex types handle short runs to motors and equipment that vibrate or move.
Is conduit required in a house?
Usually not for interior walls in most of the US, where NM-B cable is allowed. Conduit or another protected method is needed where wiring is exposed to damage, outdoors, underground or in wet spots. A few cities have local rules that require raceways more widely. Check your adopted code with a local electrician.
Can you run Romex in conduit?
In dry spots, short sleeves of conduit are often used to protect NM-B where it is exposed. NM-B is not allowed in wet locations, and underground or outdoor conduit counts as wet. There, single wet-rated wires such as THWN-2 are used instead. Fill limits also apply to cable in conduit.
How many wires can go in a conduit?
The number of wires depends on conduit size and wire size, within percentage caps.
The NEC limits fill to 53% of the inside area for one wire, 31% for two and 40% for three or more.
Electricians use tables in NEC Chapter 9 and its annex to turn those percentages into wire counts for each size.
What is the difference between EMT and rigid conduit?
EMT is thin-wall steel tubing joined with set-screw or compression fittings. Rigid metal conduit is thick-wall steel with threaded ends. Rigid gives more protection and is used on service masts and in high-impact spots.
EMT is lighter, easier to bend and common for exposed indoor runs. Each has its own UL standard: UL 797 for steel EMT and UL 6 for rigid steel conduit 4 5.
Does conduit need a ground wire?
Plastic conduit always needs a separate grounding wire because PVC does not conduct. Some metal conduit, such as EMT and rigid steel, can serve as the ground path when installed with tight, listed fittings. Many electricians still pull a green ground wire inside metal conduit for a more reliable path.
Is PVC or metal conduit better?
Neither is better everywhere. PVC suits underground and corrosive spots and does not rust. Metal suits places where the tube could be struck and where a ground path through the raceway helps.
Many runs use both: PVC underground and a stronger section where it rises above grade. Ask the electrician which type each part of your run uses and why; a clear answer is a good sign.
How deep should underground conduit be buried?
Burial depth is set by the NEC cover table and depends on the conduit type, the circuit and what is above it, such as a driveway. It also varies with local amendments. An electrician confirms the depth for your adopted code, and an inspector checks the open trench before backfill.
Sources
- ExpertCE, "NEC Chapter 9 Table 1: Conduit Fill" (53% one conductor, 31% two, 40% more than two; worked example uses the 2023 NEC), retrieved .
- NFPA, NFPA 70 National Electrical Code, retrieved .
- NFPA, NEC enforcement maps, retrieved .
- UL Standards & Engagement, UL 797 Electrical Metallic Tubing – Steel, retrieved .
- UL Standards & Engagement, UL 6 Electrical Rigid Metal Conduit – Steel, retrieved .
- UL Standards & Engagement, UL 651 Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings, retrieved .
- OSHA, 29 CFR 1910.305 Wiring methods, components, and equipment, retrieved .
- Wheatland Tube, EMT product page, retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Standards editions read from UL Standards & Engagement listings; OSHA text read at osha.gov; fill limits from NEC Chapter 9 Table 1.
Suggest a correction. We fix errors and say what changed.