Crawl Space Wiring

[Jamie Harris]

Entered crawl space do to a remodel and found all the wiring is laying on the ground none is attached to floor joists, what is the best way to fix that problem? Can I attach the wire with wire ties and staples every other joist or do I have to put boards across to attach it to?

[mike clark]

Entered crawl space do to a remodel and found all the wiring is laying on the ground none is attached to floor joists, what is the best way to fix that problem? Can I attach the wire with wire ties and staples every other joist or do I have to put boards across to attach it to?

Securing to every other joist is fine. You will want to use insulated staples, the damp crawl space will quickly rust the staples and start to break down the wire's insulation.

[Robert Meier]

This is what the NEC says about running NM cable in crawl spaces:


334.15(C) 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 (1⁄4 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

[Jerry Peck]

Keep in mind that unless the crawlspace is *dry*, as in 'meets the definition of a "dry location" in the NEC', then NM cable is *not allowed* to be used in crawlspaces anyway.

(underlining and bold are mine)
- 334.12 Uses Not Permitted.
- - (A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
- - - (1) In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)
- - - - Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction when installed within raceways permitted to be installed in Type I and II construction.
- - - (2) Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings
- - - (3) As service-entrance cable
- - - (4) In commercial garages having hazardous (classified) locations as defined in 511.3
- - - (5) In theaters and similar locations, except where permitted in 518.4(B)
- - - (6) In motion picture studios
- - - (7) In storage battery rooms
- - - (8) In hoistways or on elevators or escalators
- - - (9) Embedded in poured cement, concrete, or aggregate
- - - (10) In hazardous (classified) locations, except where permitted by the following:
- - - - a. 501.10(B)(3)
- - - - b. 502.10(B)(3)
- - - - c. 504.20
- - (B) Types NM and NMS. Types NM and NMS cables shall not be used under the following conditions or in the following locations:
- - - (1) Where exposed to corrosive fumes or vapors
- - - (2) Where embedded in masonry, concrete, adobe, fill, or plaster
- - - (3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish
- - - (4) In wet or damp locations

- Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.

- Location, Dry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.

- Location, Wet. Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

With a dry location reference to "as in the case of a building under construction" indicates that the duration of the 'other-than-dry-location' is only temporary and then the condition is eliminated by finishing enclosing the structure. Which indicates that a crawlspace which 'occasionally gets wet' would only be considered a "dry location" while operations were in progress to protect the crawlspace from getting wet, and then it could be so considered only for the limited duration of work to create a "dry location" in the crawlspace.

Some crawlspaces may well meet the definition of a "dry location" but it is likely that many, possibly even most, would not meet the test of a "dry location", and NM cable would thus not be allowed in any crawlspace which did not meet the "dry location" test.

This has been discussed here many times before - some here would consider most crawlspaces as "dry locations" while others, myself included, would consider most crawlspaces as either a "damp location" or a "wet location", certainly not a "dry location".