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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" a( [1 A* G/ Q% r/ X( d: z
abuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall
- e/ B, P" Q$ C7 N* Q& zcomply with the requirements for resistance to impact and drop as indicated below, and. S4 c5 X, X6 d' {7 ^/ f& W+ `0 w
the requirements for mold stress release distortion, in the Standard for Polymeric Materials
0 n% x% X# Z# J& S- Use in Electrical Equipment Evaluations, UL 746C.
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In UL 746C, the standards says" M8 n& G8 x0 i/ G# E* x3 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 in
3 ^2 O7 O- N3 dTable 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during& g. ]! I s$ I4 ^5 P X* ]; i
intended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,
) `( g$ V/ G: U) T" @ qand weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown) [ J. t! l4 ]
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two9 r- X, k3 B. z. F" E! ^! ]
impacts. For surfaces other than the top on an enclosure, either the sample could be supported on the1 F( y. I# X |/ q, B
side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
; S4 m& k/ a- G0 H" h% pand swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the
5 Y5 T& Z/ v5 Q+ Xsurface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests
7 c$ J1 \# r& ]* n1 v8 \& S( hin the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
4 R3 Q2 U. @' [; n' z, I1 I3 Din accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the. y; [# Z8 b! z) j% z) ]
sequences represented in Figure 58.1. |
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