I’m looking at a pre-fab building in an industrial establishment with removable floor panels. The manufacturer installed exposed THHN/THHW-2 wiring under the floor. Free air single conductors is not an approved wiring method in chapter 3. The vendor claims the space under the floor is classified as a raceway. I see nothing in the NEC to support their position. Have I missed something?
Space below floor classified as a raceway?
- Thread starter Dickyr
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Is the pre-fab building a listed product?
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
I am trying to picture single conductor run under a floor, is it in a cable tray. If the conductors are not close together then thats a violation.
Who classified it as a raceway, or as Don asked maybe its listed that way.
Who classified it as a raceway, or as Don asked maybe its listed that way.
The building is not a listed product
Cable tray under the floor. Tray cable leaves the tray to transition to a conduit riser. The outer jacket of the tray cable was stripped about 2’ before the conduit leaving exposed wiring. TC-ER can free air for lengths under 6 feet as long as it meets the crush and impact requirements of MC cable and is marked TC-ER. My position is they removed the crush and impact rating of the cable when they removed the outer jacket. The vendor claims the space under the floor is classified as a raceway, but offers nothing to support that claim. My opinion is once the outer jacket is removed then the individual conductors have to be installed in a method recognized by chapter 3
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I don't think it is compliant even if the space under the floor is a raceway because they removed the outer insulation. IMO, it is only a raceway if UL says so since chapter three requires all raceways be listed.
- Status