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It comes from UL 746C
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1 g4 K: ]% }+ `. }9 L55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical( V' p$ D4 _7 b" m
abuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall8 N; S9 G$ B2 U c" `
comply with the requirements for resistance to impact and drop as indicated below, and
4 N2 s+ B8 L7 }! G, M+ Sthe requirements for mold stress release distortion, in the Standard for Polymeric Materials3 ~, [; _" |3 d+ c8 ~) a
- Use in Electrical Equipment Evaluations, UL 746C.
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In UL 746C, the standards says; B9 }) x9 W @7 Q
% X0 b7 P' g6 ^) Z+ ?# {8 [2 X# c58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in4 v. R- v2 Z& _; {
Table 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during
9 y( s f' a* r* ~3 Yintended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,1 z! M( i& ?+ y/ {" \
and weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown( }5 D, {6 T" u1 j
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two
) a& V F0 i5 bimpacts. For surfaces other than the top on an enclosure, either the sample could be supported on the
9 b5 k8 W" p* r' @( n* Hside and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
8 H6 L5 s5 p3 n1 m8 e4 b! V; Tand swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the( F" I. q7 H6 s$ m
surface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests
3 p( ?, ]# E1 m7 v( T* b& L7 q' M* O, Tin the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
) z, s8 O) B3 k8 P% {in accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the( S* D2 X' E" f4 Z+ C+ E
sequences represented in Figure 58.1. |
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