按照UL 1598的要求，底板若是金属的话，要满足下述的要求:
Solution 1: According to clause of 11.4.2 of UL 1598. If the material of housing was ferrous, the min. thickness was 0.66 mm; if material of housing was nonferrous, the min. thickness was 0.71 mm as below from UL 1598:

若不满足的话，我们就把底板当做Openging， 按照UL 1598 12.4.7的条款，打下述的MARKING即可。
 

1. “FOR USE IN NON-FIRE-RATED INSTALLATIONS ONLY”

 
备注： 1. S16-L2， 字体高度1.6mm，位置放在安装灯具时能看到的位置即可。
       2. 驱动必须要是Class 2输出的。
 
标准条款分享：

12.4 Recessed housing

 
12.4.1 A recessed housing shall close off the opening in the surface in which it is mounted.
12.4.2 A housing shall have a minimum thickness of 0.66 mm (0.026 in) if ferrous metal or 0.71 mm (0.028 in) if nonferrous metal.

12.4.3 Where a luminaire recessed housing also serves as an enclosure, a top surface that is less than 30 degrees from the horizontal and any outer wall that contains any of the parts specified in Clause 5.3.3 shall have:
a) a maximum of two pryout slots, each having a maximum area of 26 mm2 (0.04 in2); and
b) ballast mounting slots, each having a maximum unused area of 26 mm2 (0.04 in2).

12.4.4 A recessed housing of a Type Non-IC luminaire that does not serve as an enclosure may have open holes in the shape of a slot or louvre that shall be a maximum 9.5 mm (0.375 in) wide and 10 cm2 (1.5 in2) in area. Any other open hole shall not allow passage of a rod having a diameter of 25 mm (1 in) and not exceed 10 cm2 (1.5 in2) in area. The total area of all open holes shall be maximum 15 percent of the area of the opening in the mounting surface closed off by the recessed housing.

12.4.5 A recessed housing of a Type IC luminaire that does not serve as an enclosure may have open holes in the shape of a slot or louvre that shall be a maximum 4.8 mm (0.188 in) wide and 10 cm2 (1.5 in2) in area. Any other open hole shall not allow passage of a rod having a diameter of 6.4 mm (0.25 in) and shall not exceed 10 cm2 (1.5 in2) in area. The total area of all open holes shall be a maximum of 15 percent of the area of the opening in the mounting surface closed off by the recessed housing.
 
12.4.6 A luminaire intended for installation in poured concrete shall be constructed to prevent the ingress of wet concrete into the areas provided for supply connection in a quantity sufficient to interfere with normal operation, shall comply with Clause 15.9, and shall be marked for installation in poured concrete in accordance with Table 20.1.1, Item 2.21.

12.4.7 A luminaire with openings in the housing that exceed those specified in Clause 12.4.3, 12.4.4, or 12.4.5 shall be marked for use in non-fire-rated installations only, in accordance with Table 20.1.1, Item 1.26.