CELLULAR CONCRETE FLOOR RACEWAYS

70-267 358-3. Other Articles. Cellular concrete floor raceways shall comply with the applicable provisions of Article 300. 358-4. Uses Not Permitted. Conductors shall not be installed in precast cellular concrete floor raceways (1) where subject to corrosive vapor; (2) in any hazardous (classified) location except as permitted by Section 504- 20, and in Class I, Division 2 locations as permitted in the exception to Section 501-4(b); nor (3) in commercial garages, other than for supplying ceiling outlets or extensions to the area below the floor but not above. (FPN): See Section 300-8 for installation of conductors with other systems. 358-5. Header. The header shall be installed in a straight line at right angles to the cells. The header shall be mechanically secured to the top of the precast cellular concrete floor. The end joints shall be closed by a metal closure fitting and sealed against the entrance of concrete. The header shall be electrically continuous throughout its entire length and shall be electrically bonded to the enclosure of the distribution center. 358-6. Connection to Cabinets and Other Enclosures. Connections from headers to cabinets and other enclosures shall be made by means of metal raceways and approved fittings. 358-7. Junction Boxes. Junction boxes shall be leveled to the floor grade and sealed against the free entrance of water or concrete. Junction boxes shall be of metal and shall be mechanically and electrically continuous with the header. 358-8. Markers. A suitable number of markers shall be installed for the future location of cells. 358-9. Inserts. Inserts shall be leveled and sealed against the entrance of concrete. Inserts shall be of metal and shall be fitted with receptacles of the grounded type. A grounding conductor shall connect the insert receptacles to a positive ground connection provided on the header. When cutting I through the cell wall for setting inserts or other purposes (such as providing access openings between header and cells), chips and other dirt shall not be allowed to remain in the raceway, and the tool used shall be so designed as to prevent the tool from entering the cell and damaging the conductors. 358-10. Size of Conductors. No conductor larger than No. 1/0 shall be installed, except by special permission. 358-11. Maximum Number of Conductors. The combined cross-sectional area of all conductors or cables shall not exceed 40 percent of the crosssectional area of the cell or header. 358-12. Splices and Taps. Splices and taps shall be made only in header access units or junction boxes. For the purposes of this section, so-called loop wiring (continuous unbroken conductor connecting the individual outlets) shall not be considered to be a splice or tap. 70-268 NATIONAL ELECTRICAL CODE 358-13. Discontinued Outlets. When an outlet is abandoned, discontinued, or removed, the sections of circuit conductors supplying the outlet shall be removed from the raceway. No splices or reinsulated conductors, such as would be the case of abandoned outlets on loop wiring, shall be allowed in raceways.