Does Wiring in a Crawl Space Need Conduit?

We recently discussed the details of what kind of wire you should use in a crawl space and discussed the importance of finding the right one – and making sure it is secured properly. When wiring in an attic or basement crawl space, you need to remember that you won’t have the same freedom as what you have when working anywhere else.

From elbow room to you yourself having to crawl on your belly, everything will be constricted. Working in a crawl space is definitely not for the faint of heart or those who experience claustrophobia. When wiring, a common question beginner electricians and DIY-ers ask is whether wiring in crawl space needs conduit or not.

While there is no specific requirement that dictates that the use of conduit in a crawl space is necessary, there are numerous other considerations to make that make using conduit a very good idea. From safety to indirect code compliance, everything can be accomplished by simply running an electrical wire through a conduit when wiring in a crawl space.

Does Wiring in Crawl Space Need a Conduit?

Crawl space wiring

The main purpose of a crawl space is to insulate your home from moisture. The crawl space underneath your house serves to mitigate the risk of moisture from the ground seeping into your home due to diffusion. While the crawl space in your attic is there to help you avoid moisture problems that may arise due to excessive rains.

Rainy areas can expect to have crawl spaces in the attic and the basement while traditionally, these spaces are more common between the ground and your home’s “first floor.” In desert areas, there is a lot of dew during the nights; crawl spaces in these areas can be found in the attic.

Requirement for Conduits When Wiring In Crawl Spaces – Securing Wires

While wiring a crawl space, if you find that one or more cables are either placed on the ground or are dangling overhead in a manner that someone may step on it, get entangled, or an animal or insect can nibble on it, expect to fail the inspection.

In any given crawl space, wires should be taught – not tangling.

The best way to do that is by using a conduit. When using a conduit, Code requires that it is supported every 4.5 feet (or less) to make sure that the conduit is properly secured. We would recommend that you consider securing the conduit every 2.5 to 3 feet. This way, even if one comes loose over time, you won’t have a violation on your hands.

Requirement for Conduits When Wiring In Crawl Spaces – Nonmetallic Wires

Using a conduit here is a good idea because nonmetallic wire shouldn’t touch the soil under any circumstances – be it wet or dry. We discussed the details about this in our previous article.

What Does Code Say?

The NEC doesn’t exactly say anything specific about using conduits but the cable itself. Here is an excerpt from the NEC section 334.15 about exposed work anywhere, including crawl spaces.

334.15 Exposed Work.

“In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through©.

To Follow Surface. Cable shall closely follow the surface of the building finish or running boards.

Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means.

Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means extending at least 150 mm (6 in.) above the floor.

Type NMC cable installed in shallow chases or grooves in masonry, concrete, or adobe, shall be protected in accordance with the requirements in 300.4(F) and covered with plaster, adobe, or similar finish.

© In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards. NM cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway. The NM cable sheath shall extend through the conduit or tubing and into the outlet or device box not less than 6 mm (¼ in.). The cable shall be secured within 300 mm (12 in.) of the point where the cable enters the conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment grounding conductor.”

NEC section 334.15

How to Wire the Crawl Space Under Your House With Conduits?

There are three approaches that you can take when wiring in a crawl space via conduits.

  1. Drill holes into the floor and feed the wire from the top. This will help you avoid making unnecessary contact with other lines or appliances in the wall and give you a framework of what needs to be done. We discussed this in detail in our last article.
  2. Install conduits first and then feed the wire into it from one end until it comes out the other. While this is much more convenient, the problem is that if you are installing nonmetallic wire, chances are that the wire will end up bending the wrong way within the conduit at one point or another. When that happens, you will have to pull out the whole thing again and reinsert it. This is a trial-and-error method and may either end up taking no more than 5 minutes or take up your whole day!
  3. Feed the wire into a conduit and install it. This only works if you plan to use ‘brace’ staples. For example, PVC raceways usually need to be nailed into walls while metal raceways need to be braced with the help of hooks. We prefer this method as it takes most of the guesswork out of wiring under crawl space. However, keep in mind that you will still have to make sure you aren’t installing the hook or brace into an appliance or socket, so keep a blueprint in hand. It also helps to cut the conduit down into more manageable pieces. 1-2 meters per conduit should be enough to help you pull down (or up) through the crawl space panel and install it without having to face any difficulty.

You will need to reduce clutter as much as possible. We recommend working in crawl spaces during the day because these spaces are already extremely contracted and dark. Furthermore, during the night, you will most likely find critters in the space ready to defend their home from you. You will already be constricted and won’t be able to do much to defend yourself.

About Charlie D Paige

Charlie is a massive DIY fan, with dozens of DIY projects under his belt - ranging from tiling to electrics, and concrete pads to walls. Charlie loves tinkering, seeing how things works, the outdoors and playing with power tools... so is it any wonder that he's completed so many DIY jobs over the years?

Charlie loves spreading his hard-won DIY experience with the world via this blog.