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It comes from UL 746C
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7 z' I6 J( S! L- R& H9 E! K- d8 [55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical I( W3 Y1 h' z4 b; K0 t5 F8 j
abuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall
0 E5 u0 V6 E1 M6 ^2 P Hcomply with the requirements for resistance to impact and drop as indicated below, and
) Q" A- q5 U% L) p3 d- U0 C( z$ nthe requirements for mold stress release distortion, in the Standard for Polymeric Materials+ R4 g7 q1 T" ]) S# E) ~
- Use in Electrical Equipment Evaluations, UL 746C.
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( ]+ M' ^$ I2 i# E2 O1 _In UL 746C, the standards says3 \ r2 D$ i) T
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58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in8 u& l5 A8 @& V& Z" g( v
Table 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during! c* e7 p' p$ l; r5 T3 p
intended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,2 R+ V: S a( } L
and weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown
0 e% \& v! n2 L2 Win Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two
9 P7 @3 H% U/ uimpacts. For surfaces other than the top on an enclosure, either the sample could be supported on the8 {9 t4 e2 I+ l; S; K
side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
6 @' R3 |+ q; S. [and swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the
/ @! |7 G: y/ ?$ M, psurface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests
, `' h4 [8 ~# [! Sin the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
$ F" Q a( X" t1 F4 K+ k$ jin accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the
& A0 X: \( n1 v' W& D7 k: Xsequences represented in Figure 58.1. |
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