UL 209-2020 pdf free download.Cellular Metal Floor Raceways and Fittings.
4.2 The connection of a metallic duct, cell or raceway with a fitting shall be tested in accordance with the
Grounding and Bonding Test, Section 13.
4.3 A sheet metal screw shall not be used for the connection of an equipment grounding conductor.
5 Protective Coating
5.1 Both the interior and exterior surfaces of a cellular floor unit and all broad surfaces of the accessories
mentioned in 6.7 shall be protected against corrosion by a coating of zinc and tested to the requirements in
Protective Coating — Zinc, Section 14. The lower element of a floor unit may be protected against
corrosion on both the interior and exterior by an enamel coating complying with the requirements in 15.1 —
15.3 if it is:
a) Integral with a structural member that protects it from below against physical damage during installation and
b) Constructed of sheet steel not less than 0.067 inch (1.7 mm) thick.
5.2 Both the inside and outside surfaces of header duct or trench headers shall be protected against corrosion. If zinc is used, the coating shall comply with the requirements in Protective Coating — Zinc, Section 14. If a metal other than zinc or if a nonmetallic material is used, the corrosion protection afforded by the coating shall not be less than that of the specified zinc coating. If enamel is used, the coating, at any time up to one year from the time of manufacture, shall comply with the requirements in Protective Coating
— Enamel, Section 15.
6 Cellular Metal Floor Raceways
6.1 A cellular floor unit shall be made of sheet steel.
6.2 No element shall be thinner than 0.034 inch (0.86 mm) when measured after fabrication but, if the upper element is thinner than 0.056 inch (1.42 mm), the following restrictions apply to the unit:
a) If the upper element is thinner than 0.056 inch (1.42 mm), the installation instructions mentioned in 191 shall specify that the upper element is to be protected by at least 1 inch (25 mm) of concrete:
b) If the upper element is thinner than 0.045 inch (1.14 mm), it shall be strengthened so that a representative sample of the complete unit complies with the Load Test, Section 10. The cell width and cross-sectional area need not be specified;
C) If the upper element is thinner than 0.045 inch (1.14 mm) and is not strengthened so that a representative sample of the complete unit complies with the Load Test. Section 10, no cell shall be wider than 4 inches (102 mm) or larger in cross-sectional area than 10 inches2 (645 cm2).
6.3 The thicknesses of 0.034 — 0.056 inch (0.86 — 1.42 mm) that are mentioned in 62 are the minimum values for cellular floor units as raceways for electrical wiring. Units employing heavier steel are needed and are regularly furnished where greater mechanical strength is essential for structural purposes. These units shall be subjected to the Load Test, Section 10.
6.4 The upper and lower elements of the cellular floor units shall be fastened by spot welds or other fastenings of sufficient quantity to give the finished unit strength for the conditions of use. Spot welds shall comply with the Tension/Shear Test, Section 11 and Peel Test. Section 12.
6.5 The following shall be constructed of zinc-coated sheet steel of the same thickness as the upper element of the unit (see 6.2 and 6.3 for the specific thickness):
a) A cover plate for an end joint between units where the upper element is intentionally set back from the lower element,
b) An end closure for any type of unit, and
c) Flashing for any type of unit.
6.6 A cover plate for an end joint between units where the upper element is intentionally set back from the lower element shall be at least 3 inches (76 mm) wide plus the additional width necessary to make the cover plate overlap the upper element of each of the units on which it rests — at least 1 inch (25 mm).
6.7 The width of the top of each cell of a floor unit shall provide space for:
a) Inserts to which at least 3/4-inch (19-mm) standpipes can be fastened and b) Access from header duct or trench header to the cell.UL 209 pdf download.