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It comes from UL 746C0 l2 R; u- P* g' S! y- K& p" ~
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N. K+ p8 O: P& v; X55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical
4 R' v2 K. U' g- kabuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall1 v" }9 M% H% ^: d
comply with the requirements for resistance to impact and drop as indicated below, and
7 p% k$ q \! q) M6 P9 R4 M6 kthe requirements for mold stress release distortion, in the Standard for Polymeric Materials5 v" \& O; E. P* j) I" M
- Use in Electrical Equipment Evaluations, UL 746C.
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' ~; l9 B3 N9 tIn UL 746C, the standards says+ ]4 ~8 `% o5 e6 J
3 E, ^- P( q; c3 Z( {) H58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in
9 |6 S4 k9 [1 l# C+ iTable 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during
% f5 f8 \& }8 D2 v+ n- t9 w7 Lintended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,
* C5 J5 l9 P+ u* k' xand weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown
- j# p5 ~! B* R3 s* j# K9 ~in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two( t! h0 Y6 F2 q6 N0 {5 x
impacts. For surfaces other than the top on an enclosure, either the sample could be supported on the
; ^( W) a+ _3 n6 p+ k9 H4 _side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
2 z4 G& q3 n' pand swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the
" r+ T9 e2 ]1 q& Q' t. x2 z/ Qsurface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests3 P6 n5 S' o7 Z- k
in the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used) t3 ]; X- r' V7 w2 t9 |* D. ?' {
in accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the+ o6 Y$ p2 ~$ P$ M8 O o, W% _
sequences represented in Figure 58.1. |
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