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It comes from UL 746C
% H3 ~- b6 l# M) X! E6 A* x: L1 k0 ~8 v1 z# U4 R. {
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' F" o3 d* P! A* l) Q: t! v% o5 b55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical
* T( N8 n; f7 V+ g+ G& Iabuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall7 z/ H+ }1 c4 V# P
comply with the requirements for resistance to impact and drop as indicated below, and
8 b2 [) G% Y0 U) I( f& J, f6 n" H. jthe requirements for mold stress release distortion, in the Standard for Polymeric Materials- O9 C# a8 V0 U3 G# B1 O: Q
- Use in Electrical Equipment Evaluations, UL 746C.* j* _6 t. g' I" u2 S* {7 |3 [5 \. O
5 ?+ ~/ m: j: p! }! W; N) gIn UL 746C, the standards says, D% R" ~$ e: x" {' @
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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- ~, J. o$ L, M- Q3 `3 i
Table 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during
2 z$ z- ?" Y* p; n- g2 V( X' hintended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,
' Q" l& L3 ?: dand weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown `/ w) ~+ L4 Z3 W. u) ?
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two, D+ M$ [. Y5 d- F
impacts. For surfaces other than the top on an enclosure, either the sample could be supported on the
8 E. X0 _9 F/ _2 X8 D# Sside and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord/ Z" I, N7 y- \* ~
and swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the
& p* y2 i; n% {* B( F$ gsurface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests( F! c: B% w1 C) }4 q& a# {9 @ D
in the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
9 \2 a1 Z$ t" h& u& S( R+ T& K. sin accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the% Q8 ]7 W4 Q) ]4 W
sequences represented in Figure 58.1. |
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