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Does Basement Wiring Have to Be in a Conduit

Conduit is protective tubing that prevents wire damage. Electrical wiring doesn’t need a conduit to function, but it’s an important safety measure that decreases danger from shocks or fires. When wiring a basement, it may be unclear if a conduit is necessary. 

Some regional codes require conduit even in unexposed residential wiring. This can be done to address pest issues or as an extra security measure against fire. Here we’ll explore the details of IRC code and how to go about choosing and installing wire conduiting in a basement.

As a general rule, wherever there are exposed wires, a conduit is required. In unfinished basements, wall wiring requires conduits while ceiling wiring does not. In finished basements, usually conduits aren’t required.

Wiring in Basement Ceilings Code

Section E3802.4 of IRC explains the requirements for wiring in unfinished basements and crawl spaces. For unfinished basement ceilings, conduits are not required. 

Two types of cable are discussed, NM and SE. Both NM and SE cables are commonly used for interior wiring.

NM cable, or nonmetallic sheathed cable, is fit for indoor dry spaces. SE cable, or service entrance cable, is used in above-ground wet and dry conditions. SE cable can serve as wiring for appliances, and its coverings are flame-retardant and moisture resistant.

American Wire Gauge (AWG) is a wire gauge system defining the diameters of wire, which determines current-carrying capacity. Higher AWG numbers signify smaller wire diameters. A smaller wire diameter reflects a smaller cross-sectional surface area and decreased conductance.

As per the IRC, groups of cables with two or more conductors of at least size 6 AWG and with three or more conductors of size 8 AWG don’t require conduits where they are attached to joists. These larger cables run perpendicular to joists. Use bored holes in joists or running boards (support beams) for running smaller cables.

Cable wires running through joists boards and a running board

Basement Wall Wiring According to IRC

For wall wiring in unfinished basements, Section E3802.4 of IRC states that NM or SE cable does require a conduit. 

Because walls of an unfinished basement are exposed, they pose more of a safety concern. In contrast to ceiling wires, which will rarely come in contact with other objects, wall wiring could come in contact with people or pets. 

The cable sheath must extend at least ¼” between the conduit and the outlet. The cable needs to be secured within the first foot after entering the conduit. If using metal conduit, tubing, or outlet boxes, use an equipment grounding conductor. 

CableClear -DIY Kit : Behind Wall TV Wire Kit

Only conduits listed by the IRC are allowed to be used for basement wall wiring.

What Type of Conduits Can Be Used?

According to Section 3801.2 of the IRC, the types of allowable conduits include:

  • Flexible metal conduit.
  • Intermediate metal conduit.
  • Liquidtight flexible conduit.
  • Rigid metallic conduit.
  • Rigid PVC (polyvinyl chloride) conduit.
  • RTRC (reinforced thermosetting resin) conduit.

Tubing, both electrical metallic and nonmetallic, is also allowed as it functions like a conduit by physically protecting the wires. Tubing is commonly used for short runs.

Rigid PVC Conduitunderground and wet location applications
Flexible Metal Conduit (FMC)areas that require tight bends 
Electrical metallic tubing (EMT)lightweight, easy to bend, commonly used within walls, but easily damaged 
Electrical nonmetallic tubing (ENT)mostly installed within walls (metal-frame, wood-frame, and concrete blocks)
Intermediate metal conduit (IMC)outdoor installations, exposed walls in basements, garages, and areas where the conduit might get damaged.
Liquidtight flexible conduit (LFC)watertight, and suitable for outdoor equipment
Rigid metallic conduit (RMC)areas under driveways and other extreme conditions

In unfinished basement situations, therefore, IMC is an ideal conduit.

What About Finished Basements?

Unless your local building codes say otherwise, conduits aren’t required in finished basements since the wiring is unexposed. An example of an exception to this is Chicago’s building code, which always requires conduits in order to prevent fires.

Finished basements function similarly to any other finished room in your house (in that the floors have an installed cover, walls are drywall and not concrete, and the ceiling doesn’t have exposed beams).

Even so, using a conduit might be beneficial as a safety measure against cutting and fraying wires. Conduit wiring can also improve the durability of wiring. Because the conduit is protecting the wiring, it can last longer.

Installing Wiring Conduits

After you’ve chosen your conduit, it’s time to install it. 

  1. First, map out where you’ll be running wiring (usually from a power source to an electrical box). 
  2. Next, cut the conduit to the correct length to match the wiring it’s protecting. 
  3. Then, bend the conduit to fit the path you first mapped out. 
  4. Finally, mount the conduit on the wall using straps and screws. 
  5. Now you can run your wiring through the conduit. 

If your conduit is flexible (like EMT), step 3 won’t require extra tools. However, you may need conduit benders (like those pictured below) for less flexible conduits (like IMC) to help you bend the pipes. In the case of basement wiring, you’ll likely need a conduit bender. 

Conduit Bender for 1/2-Inch EMT Conduit with Benfield Head, Wide Foot Pedal, Benchmark Symbols Klein Tools 56206
  • The traditional Benfield head design accurately and consistently performs common bends such as Stub Ups, Offsets, Back-to-Back and Saddle bends
  • Lightweight, die-cast aluminum construction
  • Exclusive design reduces rippling and ovaling of conduit
  • Wide foot pedal provides excellent stability, leverage and comfort
Gardner Bender 960H BigBen Aluminum Conduit Hand Bender Head and Handle (BH-75), ½ inch EMT, Industry Standard Measurements, 2 Pc, Red
  • Embossed sight lines for 10°, 22°, 30°, 45°, 60° and 90°
  • Industry-standard markings– 30° bend when handle is straight up
  • Bigger hook with a 5x durability factor
  • Bigger foot pedal– 40% larger

Last update on 2023-02-09 / Affiliate links / Images from Amazon Product Advertising API

In step 4, try to anchor the conduit to the wall within every 10 ft section of conduit and within 3 ft of electrical boxes or panels. 

For an audio-visual aid explaining the regulations for mounting your conduit, check out this video:

If you are looking for a simplified version of the wiring code for basements, check out my article: Basement Wiring Code (Building code explained in plain English).


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