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It comes from UL 746C
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55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical
) g3 p* z/ G5 @$ ~2 e3 Gabuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall
- e" u8 {# V, i" Q9 Qcomply with the requirements for resistance to impact and drop as indicated below, and
1 \; P% ~- k7 c- }the requirements for mold stress release distortion, in the Standard for Polymeric Materials
4 N) w) `( V5 G- Use in Electrical Equipment Evaluations, UL 746C.
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1 w8 L" E8 J7 b! sIn UL 746C, the standards says d5 r; s3 K* ?& l/ T$ k& ?9 E5 u
4 f- o$ @& I+ m4 @0 ` l; r58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in+ ?5 K5 m' Y1 t
Table 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during
7 X. I, j! z" c, n& d dintended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,; u% L# q8 t3 K! O( G. J" p3 y4 g. V$ B
and weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown+ ~2 Y" {' w0 Z e# H: n
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two9 q! {$ R4 R4 S+ p& O' }
impacts. For surfaces other than the top on an enclosure, either the sample could be supported on the# X: `) H. A0 O: y
side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord1 W; H9 `% T- w. v( x5 q
and swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the. U& e& ?" }# p, b* [( }
surface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests" L& y; L% U7 ]4 @) w5 W
in the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
( {1 ~- k/ @0 bin accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the
0 H; l2 u h6 T( L- ksequences represented in Figure 58.1. |
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